I remember as a kid watching in Bishop Ca, a contract pilot showing off in a Turbine Aero Commander make a high speed run down the runway then pulling up hard. The mechanic the next day noticed fuel leaking out of the left wing. Measuring the wing tips, the left wing was 9 inches higher off the ground and the top of the wing was wrinkled. He was no longer a contract pilot.
The only Pilot that knew how to fly an Aero Commander with amazing feats was Bob Hoover. RIP. His plane now sits in the Smithsonian. What an awesome pilot.
At Bishop i saw a Lear type private jet that was ruined when the pilots were screwing around came over the sierras crest and got caught up in the sierra wave(140 mph jet stream winds)--it bent the jet and they were able to emergency land at Bishop--i heard the jet was totaled
Retired ag pilot here. I started out in a Pawnee 260 C model. It would carry the 150 gallons, I doubt that the 235 version could. That being said, I didn’t notice you saying anything about the hopper being well forward of the CG. I’ve dumped many times. There’s always a violent pitch up if you’re not trimmed in advance for it. If he also pulled back at the same time, then that would certainly overstress the aircraft. As previously mentioned, corrosion was probably involved.
Juan with a PHD level lecture. No distractions no opinions no judgments, stayed on topic with serious attitude, as it deserves. Operating an aircraft or any other vehicle that may hurt or kill someone deserves to be taken with the most high responsibility.
I’m not a pilot, but I watch these for precisely that reason. These people have a responsibility to themselves, especially to their passengers, and to the rest of us on the ground to analyze these events and learn the lessons. Juan hosts an excellent channel.
@m.lozano9970 @Brotha00 Former railroad conductor here. I totally agree. When I was a railroad conductor, I took safety really seriously! The safety of my train crew and train passengers was my first concern. I don't like seeing preventable accidents like this. If something like this happened on the railroad, there would definitely be a rulebook violation. Someone would get fired. If you don't follow the rules and don't safely operate heavy equipment, things go wrong! That's why I followed the rulebook every trip, every time. I decided to switch jobs from being a railroad conductor. It was enjoyable, but highly stressful. I'm glad I pulled the pin when I did. It takes a toll on a person. I wanted a slower pace of life. I'm now a farmhand on a 7 generation family farm in Oregon.
I have much respect for Juan and his factual reporting combined with real experience analysis. It's really sad that this pilot lost his/her life during yet another stupid "baby gender reveal" party. RIP pilot, and sincere condolences to your family and friends.
The title of the video almost made me skip it entirely. Then I saw it was Blancolirio. Oh! Not the crap I was expecting. Glad I caught on quickly. Great coverage from Juan as usual.
I had to rewatch the part about why maneuvering speed decreases with weight... I don't know if I'm the only one who got a little lost, but I could still use a deeper dive into the physics. I appreciated that you explained it multiple ways, but for some reason it's still not clicking for me. Thank you for diving into these tragic events so that we can all learn to be better and safer pilots.
If Juan is reading this I agree. I do not refute anything in the video, but clarification on the physics of why this happens would be good. There is a detailed comment above this one that goes into how lower weight makes the airplane more nimble, and therefore able to apply more stress to the airframe. This feels right intuitively, but hearing it from a pilot would be cool.
@@kingsizedmidget7294 I was doing some reading just now and while there's a lot of talk about critical angles of attack, weight, etc, I think distilling it down to the nature of flight helped me understand it better: Flight is overcoming gravity. At straight and level flight, you are always pulling 1G. You are in balance with gravity because you are producing 1G of upward lift to counteract Earth's 1G of downward pull. When you start to climb, you pull more than 1G, because you're overcoming gravity. To generate 1G of lift in a heavy plane, you need a higher angle of attack from your wing than if you were lighter. If you suddenly dump a lot of weight, your lift is going to go up at any given angle of attack (in the same way that taking off in a heavy plane will have a more sluggish climb, taking off in a light one will have a much faster climb). So when a plane dumps a lot of water in the air while pulling some number of Gs, it will now generate more lift at that same angle of attack, which means more Gs. So what was a 4G maneuver becomes, say, a 6G or an 8G maneuver, then your wings rip off.
The way I heard it put is a heavy load will stall. A lighter load can generate more lift before the stall and thereby more stress on the frame. Think of the Va stall as a safety valve that dumps excess lift. The wings will eventually create the extra lift, but the frame can’t spread the lift. Even if the struts and spar distribute the force to the frame, now the engine mount is overstressed with its heavy load.
It’s because he’s looking at a case where the wing attachment failed, but then explains how the wing loading actually goes down. At 6:39 he briefly explains it’s not the wings that are overstressed by this issue, but the same wing loading applies higher Gs which can break other things. It’s just a bad example for the issue being explained.
Wow, what an educational video. That explains why there are several videos floating around the web showing structural failure AFTER dumping the load. Never made sense to me, but now I understand. I am a commercial pilot, helicopter, multi-engine, instrument rated, as well as A&P mechanic (all in the past, I am 80 years old). I was always keenly interested in areodynamics, and so am really grateful for your explanation of maneuvering speed dependence upon wing loading. As an A&P, I have performed the wing spar attach AD you talk about. I always liked the Pawnee 235, a very smooth and capable airplane, and a shame to see one lost. Thanks again.
I began my ag flying career flying the Pawnee and I never flew with more than 100 gallons. Never filled the hopper with liquid but we used the large hopper for dry fertilizer. I was trained at Ayers Corp. in Albany Georgia, where they make the thrush aircraft. You had to do a demonstration flight to get certified FAR 137 and part of the flight was a emergency dump. You had to learn to push the stick forward hard to keep the aircraft level cause dumping that much weight the aircraft wanted to climb like all get out.
The Pawnee pitch trim system was simple but not comfortable. A large spring on one end of a lever in the back of the fuselage attaches to a cable that attaches to the stick just above the pivot point. Moving the trim handle aft pulls, through another cable, the spring lever to tighten the spring and provide pull on the stick. Forward on the trim handle will slacken the tension on the spring and allow the nose to go down. Taking off with 150 gallons, usually the load is less for DA, will require a strong pull on the stick which the trim spring will help with. Emergency dumping with full aft trim will result in a significant pitch up unless the pilot pushes forward on the stick. The dump gate in the bottom of the hopper, also used to release dry material through a slim crack, allows slow release of liquid material as well. Liquid goes to the pump on a spray rig through a hose. The pilot may have been startled by the rapid pitch up of a full dump lever travel, fully open gate, dump. Or he may have been going for a spectacular pitch up. Or both. I personally know of two practice emergency dump fatalities.
@@gomertube I understand your comment - but a Crop Duster doesn't dump his whole load in one shot, it's sprayed in a fine mist. Which means that he's not experiencing a massive change in wing loading and Center of Gravity displacement.
Coming from a third generation ag pilot, great break down of this accident a lot of people misunderstand accidents in the ag world. Although mistakes were made, I am also leaning to the fact there was probably corrosion involved. Great job Juan keep up the good work.
Agreed. I’m imagining crumbling white spalling at the attachment. Decades of hard work, likely living outside, previous over stress and possible neglect. Condolences to the family(s).
@@davidfrench5407he probably didn’t pull up. He just didn’t nose down while he was dumping. Most of the time you’d never pull the dump handle coming out of a dive and at high speed. You wouldn’t shed weight in an emergency under those circumstances in very many situations. I started my ag flying career in an O-320 150 hp Pawnee before I moved to an O-470 Ag Wagon and later an O-520 Ag Wagon.
@@JoshJones-xd5mw from that angle he would have at least been conscious that he was heading toward a tree line. Tragic regardless of the exact cause, hopefully others can learn from this.
Many years ago ('94-'95), as a young A&P, we had a Pawnee with Hutch metal wings that were just full of cracks. We pulled the wings to repair them and found the fuselage wing attach points badly rusted internally. They looked great with nice paint on the outside, but just ugly inside with much material missing. It left on a truck to an aerospace welding facility for replacement. Scary stuff considering how they get yanked and banked in a highly corrosive environment.
@@shable1436 we had a water tank like that at work. you knew the metal had gone through when you saw the bubble in the paint. then we used to just drill it out and stick a nut and bolt in with a rubber washer.
the glory[& FAILS] always shines on the OPERATORS/pilots but, the MECHANICS and all that attached to support their mission[s] really is so important......maybe more so [idk4sure] OPERATORS are the ones also in the line of weather a vehicle or equipment is safe too operate. So it maybe would[have] passed PILOT pre-flight inspection but really it is a TEAM that creates the missions capability to be a success as in returning. The total success ends with safe return. Thanks Juan,great report w\insights Semper Prorsum ~ Godspeed
Juan, let me add some details from my experience working as a aircraft structures certification engineer: It is true that the maneuvering speed vA is defined by vS times the square rout of the design load factor. However, it is not a limit up to which the pilot cannot damage the airplane. vS is a calculated stalling speed (FAR/CS 23.335(c)), as estimated early in the design process. vA is a defined airspeed limitation to be used mainly for control surface and control system structural sizing. FAA AC 23-19A explains: "VA should not be interpreted as a speed that would permit the pilot unrestricted flight-control movement without exceeding airplane structural limits, nor should it be interpreted as a gust penetration speed." The TCDS you present in this video is of a restricted category aircraft. Although limit maneuvering load factors seem not to be mentioned in this TCDS, in the restricted category certain limitations can be lowered below the FAR-/CS-23 minimum requirements, including limit load factors and structural safety margins. That is especially used for cropdusters to allow higher take off masses. As far as wing structural loading is concerned: it does actually not change when you empty the hopper tank. Given, that speed and angle of attack stay the same. Why is that? The aerodynamic forces on the wing are unchanged as long as airspeed, angle of attack and it's configuration (flaps, ailerons) don't change. So the lift force doesn't change. The same lift force acting on a lighter fuselage lighter than before means the vertical acceleration increased, as Newton claims in his second law. To maintain level flight, i.e. maintain 1g, the pilot needs to reduce the angle of attack during release of the payload, as you explain. It seems that the unlucky pilot in the video did the opposite and increased the angle of attack, leading to increased lift forces, which resulted in structural failure of the wing.
I was a structural tech for a while and completely agree with this comment. Pilots need to stick to talking about flying. They also have a bad habit of blaming pilots only. This is not the first time wings have failed in Mexico… Mexico is known for ignoring maintenance and inspections. I’m fairly confident a properly maintained aircraft would have survived that. I see those duster fly really hard in the states all the time and no issues.
If you go to 8:12 and change the setting to 0.25 playback speed, there's a moment right around 8:14 where you see the wing fold back diagonally. At least intuitively, it seems to me that this supports what you're saying. It's reminiscent of the silly game we'd play as kids, sticking our hand out of a high speed car and "surfing" - once the angle goes a tiny bit too high, the effect snowballs as the wing flips up and back.
I used to fly PBY water bombers and we called it “checking forward” as we dropped the load. With practice, you could time it just right, so you wouldn’t even feel the load being dropped.
My grandfather flew PBYs in WWII. I was about 10 when he passed away, I wish I could remember his stories. I remember one where they ended up damaging a wing dropping depth charges
I watched that maneuver from the ground as a firefighter in So. California. The large plane was almost vertical before it passed over a ridge, dump his phoscheck and dropped straight down the 3000 foot mountain. He missed the ridge by about 50 feet. Most of the pilots back in the 80's were ex-military guys.
@juliogonzo2718 gathering of the eagles web page has some stories. Major Jack Randolph Cram (USMC), was the personal pilot of Marine Gen. Roy Geiger's PBY-5A, the "Blue Goose." On 15 Oct 1942, he won the Navy Cross and permanent nickname " Mad Jack" in operations at Guadalcanal. There's a great story of Cram rigging that PBY with torpedoes and dive bombing Japanese ships. J R Cram was my grandfather's cousin. I met him when I was eleven years old in 1967. I believe he was working in DC at the time. He had a large great Dane named Ace that my sisters and I got to play with.❤
That’s really cool. Where did you fly? I would really like to know more about pby water bombers. The old Martin mars often flew over my home as a child.
These crop dusters are loaded to cover several fields before they need to be reloaded. The emergency dump is used if you have a in flight emergency and have to take weight off of the air frame for an emergency landing.
Excellent video as usual! As a sometimes-getting-paid-for-it aerodynamics by training Ph.D. I view this through the basic physics lens. The force on the wings is proportional to the AoA and square of the airspeed (hence the exponentially rising limit curve vs. air speed). For a given speed, at heavy weight when you pull back on the stick the airplane cannot increase it's angle of attack quickly due to the airframe/load inertia and thus the rise in force on the wings is slow. At low weight when you pull back on the stick the AoA can rapidly increase because of the lower inertia/weight and quickly get to the point of generating a huge amount of force that's trying to yank the rest of the plane upward. Ever put your hand out the car window like an airplane wing and tilt it upward a little too much too quickly and your hand snaps upwards. If your hand was made of lead it would snap upward far more slowly than your water-ish made hand. That and the heavy plane/hand was already at a higher angle of attack to counter the aircraft weight/hand weight to keep it in the air. Ever see a light paper/balsa wood airplane suddenly get too much lift it pitches up very quickly whereas a heavier paper airplane does not pitch up nearly as fast. Excellent video as usual.
Ok that makes sense. I was about to rewatch the video. I was also wondering if destructive oscillation could be a factor as the wing load drops quickly as the water is dumped then loaded quickly when the pilot pulled up?
Thank you for confirming the reason for the "low weight" limits on maneuvering speed. This is the same reason why some friends who work as maintenance/defense contractors warn pilots to be extremely careful when flying aircraft on short ferry flights. Minimal fuel, no pax or cargo (or wing ordinance!) the jet will respond very differently than it normally does, and this is especially noticeable on takeoff as the jet will accelerate quickly, and overspeed the gear and flaps, etc. and a sudden pitch up, is at high risk of exceeding limits. Another risk for inexperienced pilots is scraping the tail on the runway.
Excellent explanation. Thank you, from one PhD (in an entirely different field) to another. I’m a student of aerodynamics as a hobby, especially low-speed aerodynamics for soaring and the use of negative flaps (“drag buckets”) for increasing L/D at various speeds. So this nice summary really resonated with me. Thanks again.
Great video Juan! If I understand correctly, because the mass of the load being dumped is about 80% of the empty weight of the plane, after release, the instanenous g-load is increased to 180% of the value before dumping. Thus if the plane is already pulling 2 Gs at the moment of dumping, it is now pulling 3.6 Gs the moment after dumping. No wonder things snap.
They wanted to hire a stunt plane for their party. I don’t have an issue with that. At the end of the day the pilot needs to make the choices for safety of their aircraft. Blaming the couple for this is just silly.
Because people want to make a big deal and post it on social media. Narcissistic behavior while people die, houses burn, forests burn and people get maimed for these stupid stunts. Boy or girl who cares!!!
As a private pilot this was never mentioned to me and I was unaware that at minimal weight this could be a factor. I guess that's why they call it a license to learn. Great video.
It's troubling that your training did not cover this. If you got your license in the US, please re-read chapter 5 of the PHAK (Aerodynamics of Flight), specifically the section on "Load Factors", which includes everything mentioned in this video, including the V-G diagram.
@@oisiaa The POH of the PA28 and C172 that I'm familiar with both publish a VA at multiple weights, showing a lower speed for lower weights. I have an extra step in my preflight planning that determines my VA based on my weight by interpolation. This is always my personal Vne
@@owisagrom I fly big jets where Va isn't really a thing. "Maneuver speed" speed for us is the speed at which we can fly a 30 degree turn with stall margin. We have a hard g limit, not Va.
Once again you did an outstanding job gathering all this info and putting it all together so we can all understand and learn from these horrible accidents.
Flying fighters, we use a version of the V/G diagram to show 2 important features of performance-corner velocity (smallest turn radius which happens to match Vm) and best turn rate airspeed (faster and G-limited). If you lay two competing [Em] diagrams on top of each other, you can find your maneuvering advantage. As always, fantastic video Juan.
I've got around 7000 hours in the PA-25 235 as an aerial advertising pilot (banner towing). Our operating manual had the maneuvering speed listed (yes it is 120 MPH). I'm glad you started by mentioning the variable maneuvering speed as the weight changes. Our planes were STC'd with 75 gallon tanks where the hopper used to be (3 gallons unusable) so we had to be aware of the maneuvering speed vs weight difference as we flew cross-countries to different locations. It's a very fun and rugged airplane when used correctly. I usually called it the flying pickup truck.
Great class for all pilots. Usually, there is more than one link broken for an accident to happen, this may well be the case. Thanks Juan. Poor guy didn’t know what he was getting into. RIP.
If I follow (which I my not), by halving the planes mass and not changing it’s profile in the air, it’s accelearation from aerodynamic forces double - which if you’re pulling a 1-g nose up maneuver as you do that, you go from 1g to 2g of force on the fuselage. The wings may be fine taking those forces, but it’s going to maneuver more nimbly, and it’s going to mean 2g of force on the engine mounting in the nose.
@@Relkond thanks, thats what I needed to finally understand it. Reducing the weight suddenly doesn't change the lift the wings are creating, but it does increase the G's the airplane is pulling.
Maybe, but the manoeuvre itself was pretty crazy too, I'm not an expert by any means but I would wonder how much of a difference that might make when the pilot put the plane under such forces in the first place. The wing might have snapped regardless of any wear and tear. If it is a factor, I'd expect it to be a footnote rather than anything that significantly contributed to this outcome.
@IrishmanAC many Ag pilots pull off these maneuvers several times on a daily basis. I have witnessed iy many times here in Ohio. I feel this pilot miscalculated his load and attempted a maneuver he was used to. A miscalculated load, and a potentially structurally weakened aircraft lead to this.
@@pennhiker5117 yes, it does. Unfortunately there are those owner/pilots out there that think it'll be ok unless they get caught. Sad but true. It happens a lot in the private aviation field and really is scary.. that said, I don't mean to accuse the pilot in the video.
Maneuvering speed was an area one of my instructors drilled into me. (I had three total and lost each one as they moved up into the airlines) I’ve never seen that chart before but I can say that its a great tool, especially if you want to explain why less weight will decrease maneuvering speed. I assume the same logic would apply when 12 skydivers exit an aircraft. Great teaching moment. I enjoyed the entire presentation.
The way I heard it put is a heavy load will stall. A lighter load can generate more lift before the stall and thereby more stress on the frame. Think of the Va stall as a safety valve that dumps excess lift. The wings will eventually create the extra lift, but the frame can’t spread the lift. Even if the struts and spar distribute the force to the frame, now the engine mount is overstressed with its heavy load.
Great video Juan, as always. One detail: if you step through the video you’ll see the spar attach did not fail but the struts collapsed. First the rear (the wing twists in torsion first) then the front strut, and whole wing rotates around the fuselage about the spar attach pin.
This is again a sad story where pilots are pushed towards being a “flying circus” with a bad outcome. I will file this video for all my aerobatic, UPRT or instructor students, when I’m desperately try to explain a flight envelope. Thank you Juan for doing it for me! I like the visualisation with different colours. 👍🏻
Thanks! There are numerous Airworthiness Directives on the struts, the one you showed for the main spar attachment and another for the aft spar attach. It does not look like either of those failed. As you mentioned, it does appear that the left wing failed at the outboard strut attach point. I’ve not done crop dusting with these birds, but I do have over 600hrs in Pawnees on glider tow duty. We are about 1200# below MaxGW. You are hard pressed to get over 120mph in a dive without that extra weight.
It looks like the left wing bent backwards, causing a runaway pitch-up moment until it snapped off. That is, in the first frame where the wing flexes it looks like the wingtip flexes first, rather than at the root. You can even see the wing crease just outboard of the root.
0:17 I love how whoever is operating the camera paid enough attention to the plane to stay with it as the wings fold, but then just pans back to the soon-to-be parents as if they didn't just see what we all saw. "Screw that guy... it's a girl!" 🤔🤨
It probably didn't even register in their mind what just happened. That plane was literally flying by. 100+ mph. They just swung the camera back behind them and then right back to the over-spending, braggadocios couple.
I doubt very seriously that anyone was aware of the tragedy that just happened. I would love to see video of the next 5-10 minutes. My guess is that the mood changed drastically once reality sank in.
They were watch the video of it right when the wing bends there is a terrified high pitched scream followed by a glimpse of people running away towards it, people were absolutely aware of what happened the second it happened and the cameraman had a perfect view so put two and two together
Dumping the hopper causes an extreme nose up trim, it will take you by surprise if your not ready for it. A massive push on the stick is required during the dump. I am guessing he was a banner or glider tow pilot, not an ag pilot.
Thanks, that fits much better to what the accident video shows than Juan's explanation. Reducing weight (e.g. by dumping cargo) while in a turn with a constant wing-loading will increase the g-force on the aircraft, which can cause structural failure. But in that case it wouldn't be the wings that fail, those are at a constant load as we said. What would fail are the "fixed weight components", i.e. the high gees would rip the engine off its mountings or so. What happened in the accident video was that the aircraft pitched up massively as the hopper was dumped. As Juan explained, at lower air-speed that would have led to a stall instead of a structural failure, but I don't believe the pilot intended to put the aircraft into a stall so close to the ground. So an unexpected change in trim that caused the nose to pitch up is a more likely explanation.
@@DrAHorn The final picture in the video is stopped at exactly where the wing failed. You can clearly see it twisting as the attachment point failed. So the wing was fine. Just it decided to go one direction and the body another. With a poor couple of bolts left somewhere in the middle.
@@josephoberlander Well, O.K. it may technically not be the wing. But it's still part of the structure that is engineered to support the full force that the wings can carry.
@@DrAHorn True. It does look like it failed a bit earlier than it should have, but such are old machines. A little deformation, a loose bolt, a bit of rust and it could be still up to spec but just barely/needing replacement soon. It will get interesting to see what the reports say about the condition of it and the maintainence recrords.
Aero Engineer here with a lot of ag design/testing/certification testing..... When you emergency drop, the effluent drops down entraining air which increases the angle of attack at the horizontal tail which increases the down force at the horizontal tail. This tends to pitch the aircraft nose up without any input from the pilot. A number of AT-802's have been lost because of this phenomenon, but in this case the horizontal tail stalls and the aircraft bunts (uncontrollable nose down).
I think you have the answer sir. After watching the video frame by frame it appears the tail got sucked down by the water down wash coupled with sudden wing unloading. Maneuvering speed has to do with full control deflection limits, as I recall from ground school.
While it is true that low weight does increase max Gs for the same control input at any given speed, the lift of the wings and so the couple at the wings roots is the same, so I don't see how low weight can be to blame for this kind of structural failure. Other parts of the airframe indeed are more stressed with more Gs, but not the wings because of this low weight situation. Thanks for your response, it meens a lot for us GA pilots your videos. Congrats.
Lightly loaded, the wings can produce more lift before stalling because it has more available angle of attack. The way I heard it put is a heavy load will stall. A lighter load can generate more lift before the stall and thereby more stress on the frame. Think of the Va stall as a safety valve that dumps excess lift. The wings will eventually create the extra lift, but the frame can’t spread the lift. Even if the struts and spar distribute the force to the frame, now the engine mount is overstressed with its heavy load.
Unfortunately, I could not wait for today's class. Once again you did a stellar job. Sir, you save lives with your channel. Sorry for the pilot and his family. RIP young man.
It's amazing to me the lengths ppl will go to reveal a gender of a baby. Pilot killed, wild fire started and so on so on. Call or text your friends it a boy or girl. Ppl died because of this nonsense, enough all ready
When an aircraft manufacturer has a bit of a reputation for wings occasionally folding up unexpectedly, keeping any unnecessary wing loading out of a drop like this seems like an even more crucial, basic safety practice even without the corrosion factor being known. It's not just ag sprayers or GA that have to face corrosion risks head-on, either. Airline aircraft deal with corrosion issues as well, and the manufacturers have their own specialist "corrosion gods" who get to know the issues seen in the field, and their remediation, in great detail. Boeing had quite the send-off a few years ago for their retiring master of the subject who spent lots of time deep in the structure of 747s (esp. under lavatories and anywhere condensation tended to form), and even in their fuel tanks where organisms would live feeding off the jet fuel and creating issues in tropical climates, particularly.
One thing doesn't track for me - yes, the g-load increases when dumping weight and keeping airspeed and angle constant, but g's don't break metal - Newtons do. And while we usually think in g's because the force comes from inertial loading, in this case the force exerted by the fuselage on the wings didn't increase - the only force trying to tear off the wings was still just the constant lift. (What could have changed was the distribution of forces inside the fuselage, and slightly in the wing itself). I am more inclined to believe that the CG moved aft abruptly and the aircraft pitched up, increasing lift force on wings and thus causing a break.
I used to fly the Pawnee (later the Canso) spraying in Africa, in the 70s. It is now a nostalgic chapter of my life and I found this video both illuminating and sad. Thanks Juan, you ALWAYS produce such high value information. Pilots would do well to follow EVERY ONE of your videos. Thank you.
Also the modified wings from round to square wingtips may have a big impact in twisting moment on the wing structure? It seems that the wing starts to fail by first being twisted and by then all structural integrity is kind of gone.. This could also be a lesson about the possible impact of modifying aircraft and the importance of verifying tests. As others have stated about the wing attach fittings, I did a reinforcement on a tug-Pawnee here in Sweden some 10 years ago. The Pawnee look rugged by the looks, but in my opinion is a pretty weak construction. At least the part forward of the cockpit. thanks for a great channel Juan! You have a nice way of explaining 👍 greetings from Sweden 🇸🇪
Why would the wingtips be modified, from round to square? My thoughts are that this aircraft could be used for "events" and that the square tips used be used to accommodate smoke canisters. Also no doubt is pink and blue flavours.
Juan, as always a spot on analysis of a tragic event. I have great respect for your aviation knowledge! I'm not sure if you know, but when a UA-cam video is paused you can use the greater than less than keys to move one frame at a time. I find it useful on many videos when trying to see something important. Of course the quality of the freeze frame depend on the quality of the video. Cheers!
@EmesiS - Thank you! This reminds me to search for an instructional video for using UA-cam. And if you use the period and comma keys, the increments are much shorter.
@@StevenBruce-s1o Lol...well that's basically what I meant. Same keys, I just always say greater and lesser instead of comma and period. I didnt even think about the difference when I posted....duh. if you do hit shift, that changes the speed and not the frame increments. Anyway you figured it out....cheers!
Dear Juan as an engineer i am not sure I agree with your explanation. Dropping weight before/during the pull up actually reduces the load to be carried by the airframe. So the drop is not the problem in my opinion but the sharp pull up that exceeded the limits of the wing. The CL215s always do sharp pull ups during the drop while fighting fires. Just my two cents and greetings from Athens.
Even though it reduces the load it increases the amount of G force being applied on the aircraft for that moment as the weight of the aircraft suddenly decreases. Kinda like if you were pushing an object and object suddenly moved so you fell forward...except with lift. There is less aircraft weight to be lifted causing a bigger spike in g force for that moment in time.
Currently working on my Bachelor Thesis about fatigue damage in aerial firefighting. This video including the comment section is great! Thank you all :)
I had seen personally three of that aircraft in the early 70's where the tubing next to the tail wheel was corroding apart from the chemicals, speaking of such, why would anyone, especially pregnant, want pesticides and defoliant tank water to be dropped on them???
Anyone who wants this kind of nonsense for a 'gender reveal' probably has a IQ so low that they struggle with any concept above 'Whoo pink pretty stuff'
As I recall… during the low level skip-bombing assault on the Ruhr Valley Dams during WWII, 5 of the 8 attempts resulted in loss of aircraft to both defensive gunnery and catastrophic structural failures.
I have a small 2x2” piece of “AJE” , a Lancaster lost on the dambusters mission, AKA “operation chastise” … flown by Flt. Lt. Norman Barlow and his crew, lost to ground fire at 23:50 hrs May 16-17 1943… Godspeed boys…..
Only one aircraft was lost over the dams, that happened at the Mohne dam. It pulled up but one wing was on fire and it broke up and crashed. The Eeder dam did not have defences. The aircraft that had to attack that dam all pulled up very steeply but none broke up.
@@chriss.4147 He could be talking about training / testing too. There's film of a least one where the bomb bounced into the tail and the aircraft went straight into the sea.
When flying the wing generates lift which causes the wings to bend upwards. The weight of the aircraft causes the wings to bend dowards. This is called G relief. The heavier the aircraft the greater the G relief. If the weight of the aircraft is suddenly reduced the amount of G relief is also reduced. This can be seen launching gliders by winch. As the glider climbs higher the force pulling the glider down increases as the angle of the cable gets steeper. During level flight the Vne of an ASK-21 is 151 kts the maximum winch speed is 81 kts. (All the other numbers in the VG graph will change pro rata). This effect is most noticeable when winch launching long winged gliders such as the ASH-25.
Great reminder to all of us sir!! Some aircraft are more susceptible than others. I loved the way you went back to the basic chart to reiterate how dangerous exceeding design limits can be!!! Thanks again Juan!!!👍
The most eerie thing in my opinion is that the person filming definately noticed but filmed back to the couple as if it didn't happen. Like they didn't want the plane crash to ruin the day.
its a somewhat common response to some types of traumatic events. almost as if the brain just overwrites that portion of memory to avoid dealing with it. always creepy to see though. people dying and everyone just going about acting like its not happening
@@kekke2000 "he person filming definately noticed " The phone follows the plane past the point where the wing broke, but that does not mean the person holding the phone was looking at the phone or the plane.
I was trying to explain to maneuvering speed to a student pilot the other day. This was a grim demonstration of its importance and the results of exceeding it.
I just can't relate to people who do stuff like this. I guess trying to do something cool and memorable trumps good sense. A flyby with a plane is cool and I've seen things like this done with skydivers and it makes no sense. It's cool if it all goes well but look at the penalty for failure!
It looks like they were still celebrating even though they literally watched the plane break up directly over head. Maybe they thought the wrong falling off was part of the show?
Juan, I love how can you be such an aviation nerd AND help us fellow aviators with your experience, research and insight at an understandable level. Keep 'em coming, and come visit us in Idaho again sometime!
So the person filming the accident follows the plane up until the wing breaks and the plane disappears from line of sight then turns the camera back on the couple hugging and keeps it there like nothing ever happend? RIP to pilot.
Great job Juan. Wouldn't we say a wing has two critical AOAs? The positive AOA, and negative or inverted AOA? Probably not too relevant to this video however. Nice work.
Hey Blanco, when the water is dropped rapidly, remember the wings were making 3,000 lbs of lift but the aircraft now weighs only 1,600 lbs. The airplane climbs violently, sometimes exceeding the available down elevator.
I'm no expert, but this doesn't sound right to me. The wings are placed at, or even slightly behind, the center of mass of the plane; so even with the large discrepancy between lift and weight, it doesn't have a significant moment arm to operate around, and if anything, with the wings behind the centre of mass, that would create a slight nose-down torque upon release -- but regardless, the tail fin is there to keep the plane flying generally straight. So I think you're confusing linear forces with torques. I mean, the plane can fly straight and level when full, and can fly straight and level when empty. It's just a angle of attack change to move towards those two regimes.
@@TheHuesSciTechThe tank in that Piper looked to be forward of the natural CoG, mounted in front of the pilot like that. The dump probably moved the CoG backwards a bit, and did so suddenly. Given the likely strong nose-up trim required at maximum weight, even a small movement of the CoG could induce a strong pitch moment if the pilot wasn't ready to counteract it.
@@TheHuesSciTech it has nothing to do with CG. Presuming everything is in equilibrium, trim is set, the horizontal stab is neutral or pulling down slightly and the wings are making 3100 lbs of lift to carry the 3,000 lb gross weight straight and level. Now dump the 1,500 lb load in about 3 seconds. The airplane will pitch up violently, not because of any change in cg, but because the wings are still making 3100 lbs of lift but you only weigh 1500 now. Try it sometime...ag pilots are accustomed to taking 20 or 30 minutes to empty their hoppers, not 2 or 3 seconds. Best of luck, and be ready with ALL the forward stick!
I’m probably in the minority but I think that gender reveals are a stupid, look at me act. I remember a few years ago at least one of them started a forest fire that burned multiple houses to the ground. Why don’t people just wait until the child is born and announce its gender then?
I confess, I am confused by this explanation. A stable aircraft will trim at a lift coefficient. This, when the load is dropped, assuming it is on the CG, the aircraft would pull g to maintain the lift coefficient. There would be no effective load change on the wing. But! If the load is in front of the CG, you would get a trim change increasing lift coefficient … is it possible this has nothing to do with VN and everything to do with sudden trim change unexpected by the pilot combined with a pull-up?
This is why I'm your patreon! You are able to explain short and clearly, whatever may be intrincate and hard to pick up from harsh or sad events like this!
06:17 - Yes, but it's not the wing loading or "X" pounds of lift that break the wings - it's the g's. On the examples given the g's are fixed at 4. It takes an "X" amount of g's to break a wing, at whatever wing loading or lift force. At a lower wing loading the wing may not stall (which would unload the wing) before reaching its design g-load factor and may break, hence the lower maneuvering speed at lower weights.
It's a bit more complicated. The limitations are given in "g"s because it is an easy to express limitation. However, when you change the masses configuration of an aircraft there are changes in the forces, some forces increase, some decrease. In this case, if you unload a fuselage-mounted tank, the wing attachment forces decrease while the fuselage structure (engine mounts in particular) experience greater forces for the same angle of attack. That's why manouvering speed often decrease with weight.
@@blancolirio I’m not sure he does have it correct. The lift the wings produce depends only on airspeed and angle of attack. In your example if the 16000 lb airplane pulling 4Gs suddenly releases 8000 lbs of weight it won’t be pulling 4Gs anymore it will be pulling 8Gs unless the pilot lowers the angle of attack to reduce the lift. An aircraft that drops weight at constant angle of attack is likewise going to accelerate upward and climb without any pitch input from the pilot. So that’s what likely happened in this mishap. The pilots 2-2.5 G pull-up became a 4+ G pull-up as the water was released overstressing the airframe in the process. This would have been exacerbated if the aircraft was above maneuvering speed.
Right, was wondering why no one else had pointed this out! A guy plumetting to his death... Pan back to the choreographed reveal hug. Lost a little more faith in humanity...
THis has @@worldwideflyby prompted much reaction. BUT I highly doubt they really seen what we did in a post flight event w\video review...think about it PERSPECTIVE → point of view[actual] then also add in SPEED & flight altitude & then window of visual [time] before out of. SemperProrsum~Godspeed
Excellent Training! Thank you Sir! I've been around a while and Never really thought about this Operating situation! Totally was the Factor here! As I think about it, I'm thinking the Pilot should have realized this if he had extensive experience Operating as an Ariel Applicator! I'm wondering how Many Drops of the nature he had Performed! Ya, lack of experience probably was a Factor here! I'm thinking a experienced Operator of AG Aircraft would have made a Normal Drop without a Hugh Pull Up Maneuver! God Speed too this Pilot! This accident and it's analysis may help save other Pilots! Great example of Accelerated Stall Possibilities! Thanks again!
Thanks for the insight Juan. It only takes one mistake to pay with your life. Simply put "small corrections" That's what my Dad would say when I was first learning to fly as a kid. I was a career pinch hitter with my Pops you could say. Every flight was a learning experience :)
Great explanation. I've never even seen a V-G diagram before, so this was all new material for me. I wish you could have shown us a modified V-G diagram showing the unloaded state for comparison. My only complaint (albeit a minor one.)
Counterintuitive... yes! I definitely learned something today. Your analysis videos and commentary on real world events are extremely useful and educational. Nobody better to comment on aircraft occurrences than an experienced pilot. Thanks again!
I fly SEATs and I can tell you that the airplane does pitch up when the load comes off. If you ever watch a cockpit view you’ll see the pilot push the stick forward (full forward for a salvo). I think the pilot wasn’t ready for the pitch up, was well above ideal drop speed, and the rapid increase in G’s caused structural failure. Keep in mind that the wings are producing around 2900lbs of lift at that airspeed and pitch angle. When the plane loses, let’s say 1000lbs within a few seconds the excess lift causes the plane to pitch up rapidly. If you aren’t ready to counter that with forward stick, you will find yourself behind the plane. This tendency only increases with speed.
Thanks a lot Glenn. An extremely clear lesson on structural limits. And the difference between an oooold crop dusting utility aircraft (turned into a light firefighter aircraft) and an aerobatic aircraft…
Thanks for the video. I always thought that the point of a crop duster was to release chemicals in a very slow, controlled way. I understand that the fire suppression planes need to make a hard drop at once, but I thought crop dusters were made for a different kind of use.
Yes, normal operations of crop duster would release small amounts over time, however as explained in the video there is an emergency release which was used here.
@@guntherberger596 I remember him saying that there was an emergency release. I wonder whether the manufacturer established conditions under which the release should be used. For instance, if the engine fails and the plane is going to crash anyway, I can see value to releasing the chemicals so that a rescue doesn't have to deal with the chemicals. I wonder whether the "owner's manual" for the plane basically says that if one isn't crashing already then using the emergency release is likely to cause a crash.
There are too many examples unfortunately. April 2021, 2 people died crashing into water after a gender reveal stunt in Cancun. November 2019, a pilot survived a crash after dropping pink water for a gender reveal in Texas.
@kekke2000 Really unbelievable. And I must be really out of it - I had never heard of a gender reveal party. We used a cute mailed announcement. Or nothing. I'm sure mail changed to email. But a pink water dump? 🤷♀️
It seems likely corrosion and the famed weak Piper spar figure in this somewhere. I remember the Piper arrow wing failure in Florida and the Cherokee Robinson helo midair with that spar failure, both a few years back.
lower weight causes lower safe manoeuvring speed because ? You can pull more g load with full control input when the plane has a lower mass?? Did I miss that exact correlation take away from the graph ???
Our gender reveal was 20-30 homemade cards mailed to friends and family. I’m sure they spent more time looking at the cards than these party guests spent pondering an associated death. I’m sure some of this is due to people’s wide-ranging ignorance these days. Some of the Wings over Dallas phone footage captured people asking whether all the aluminum falling from the sky was part of the show. As for this crash, it’s pretty close to call, but it looks to me like the wing was already tweaked before the rapid nose-up.
I dislike gender reveals so much, that was something never happened years back in my country, now the people has to mimic the stupidity from other countries... Jeez
I appreciate Juan's thorough explanations. But I too wonder if that wing folding up like that was inevitable after enough instances of similar abuse, regardless of load dumping.
For each of our three the gender reveal was after the birth, the doctor told us the gender of the baby and when we showed the baby to family and friends we told them the name and they figured it out. At every doctor appointment we had to tell them, we don't peek at Christmas presents from December 25th and we don't want to know the gender!
The G-bend limit on this diagram, is the horizontal line at a constant G. It does not change with speed. What changes is the stall speed, which increases with airspeed and with G. R
Wow this was an awesome assessment and breakdown. I never knew the dangers that those fire planes are in when dumping a load. I couldn't image how difficult it would be to drive my car if I had to worry about speed, g-forces and weight to keep my tires on when going around a corner.
Not exactly. You couldn't tear the wheels off a car by turning sharply. You would either start to skid or roll. I am talking about operating something that is very fragile and you can destroy by fairly normal operation. @@StevenBruce-s1o
Wouldn't have even thought that dropping something (heavy) from an aircraft would be legal, outside of some exceptions like agricultural or fire fighting activities. Far better to release colored smoke or something like colored confetti/chaff
It’s legal (in the US) as long as you make sure it won’t harm anything on the ground and you have landowner permission, etc But low altitude dropping over a crowd in the US would probably be a quick license pull
Early Pawnee ‘s had wooden wings which have broken. Most were updated to aluminum. We used them for banner towing as some companies still due. That could have happened here.
My thoughts as well. He is essentially dumping over a half ton of weight from the nose of the aircraft in less then 2-3 seconds. Seems like that would cause a CG shift, that maybe he tried to counter too much?
I'm leaning towards structural failure from either pass flights or an ongoing issue that was unnoticed. That plane should not have failed during a simple maneuver like that.
@@flyinbryanfpv even if it was perfectly centered on the cg of the airframe that much weigh loss in that time frame would cause it to at least "balloon" up a bit. Which the pilot might have tried to counter with forward stick. Which would have been bad idea. I am not saying I know any of these things to be fact, just stating my own point of view from the video provided. It could have been coupled with a problem airframe as well. Just a bad way to go and for no good reason.
@omegawolf81 I agree with you. The part I was addressing was the possibility of cg shift being the cause. Its more likely the sudden loss of 1000+lbs of water and pilot input causing the catastrophic failure
Imagine you successfully dump your pink only to lose a wing and in less than a second you know you’re screwed. But in that moment you see the couple hug and kiss in perfectly coordinated love and joy just as you go in. I wonder what last thoughts you might have in that moment. I wound hope the pilot saw the joys and love and smiled knowing he’d successfully completed his mission, or if he never saw anything because of adrenaline dump and disorientation ahead of impact. It’s such a strange scene as it has birth and death, joy at love and birth and a flaming end and violent lonely death.
You mention on the air tablet the water/retardant tank is centered on the air frame. On the accident plane you said it's toward the front? Could that have created a seriously or of trim nose up configuration?
I have always loved aircraft but I am not a pilot. This is an excellent reminder to me why I should never try to fly. The details that must be remembered around the weight, G-force, stall speed, etc... are not my strong suit. Would love to be a mechanic again, but you guys that are (good) pilots get all my respect.
wow I never thought about it, counter intuitive and scary.. of course I never had the option to dump all my passengers out the bottom of the aircraft and yes I have had my mother-in-law in the back before :)
I remember as a kid watching in Bishop Ca, a contract pilot showing off in a Turbine Aero Commander make a high speed run down the runway then pulling up hard. The mechanic the next day noticed fuel leaking out of the left wing. Measuring the wing tips, the left wing was 9 inches higher off the ground and the top of the wing was wrinkled. He was no longer a contract pilot.
The only Pilot that knew how to fly an Aero Commander with amazing feats was Bob Hoover. RIP. His plane now sits in the Smithsonian. What an awesome pilot.
@@dutchtubahe was definitely a smooth operator.
At Bishop i saw a Lear type private jet that was ruined when the pilots were screwing around came over the sierras crest and got caught up in the sierra wave(140 mph jet stream winds)--it bent the jet and they were able to emergency land at Bishop--i heard the jet was totaled
he had a future in the fast food industry
@@dethray1000LOL. Of all the things that never happened, this never happened the most. 😂
Retired ag pilot here. I started out in a Pawnee 260 C model. It would carry the 150 gallons, I doubt that the 235 version could. That being said, I didn’t notice you saying anything about the hopper being well forward of the CG. I’ve dumped many times. There’s always a violent pitch up if you’re not trimmed in advance for it. If he also pulled back at the same time, then that would certainly overstress the aircraft.
As previously mentioned, corrosion was probably involved.
One other thing. Water weighs 8.33 pounds per gallon. Assuming 150 gallons, that’s an additional almost 50 pounds.
Looking at the pitch up, it’s entirely possible that the sudden change in the moment arm at the release of the load caused it as well.
Yup.
@@bryanrackard9268 Elvis, you captain now?
Thanks I was wondering how the CG was affected.
Juan with a PHD level lecture. No distractions no opinions no judgments, stayed on topic with serious attitude, as it deserves. Operating an aircraft or any other vehicle that may hurt or kill someone deserves to be taken with the most high responsibility.
I’m not a pilot, but I watch these for precisely that reason. These people have a responsibility to themselves, especially to their passengers, and to the rest of us on the ground to analyze these events and learn the lessons. Juan hosts an excellent channel.
Unlike that other UA-camr…. You know the one…. Named Dan…. Lol jk love them both!
@m.lozano9970 @Brotha00
Former railroad conductor here. I totally agree. When I was a railroad conductor, I took safety really seriously! The safety of my train crew and train passengers was my first concern.
I don't like seeing preventable accidents like this. If something like this happened on the railroad, there would definitely be a rulebook violation.
Someone would get fired. If you don't follow the rules and don't safely operate heavy equipment, things go wrong! That's why I followed the rulebook every trip, every time.
I decided to switch jobs from being a railroad conductor. It was enjoyable, but highly stressful. I'm glad I pulled the pin when I did. It takes a toll on a person. I wanted a slower pace of life. I'm now a farmhand on a 7 generation family farm in Oregon.
I have much respect for Juan and his factual reporting combined with real experience analysis.
It's really sad that this pilot lost his/her life during yet another stupid "baby gender reveal" party.
RIP pilot, and sincere condolences to your family and friends.
The title of the video almost made me skip it entirely. Then I saw it was Blancolirio. Oh! Not the crap I was expecting. Glad I caught on quickly. Great coverage from Juan as usual.
I had to rewatch the part about why maneuvering speed decreases with weight... I don't know if I'm the only one who got a little lost, but I could still use a deeper dive into the physics. I appreciated that you explained it multiple ways, but for some reason it's still not clicking for me. Thank you for diving into these tragic events so that we can all learn to be better and safer pilots.
If Juan is reading this I agree. I do not refute anything in the video, but clarification on the physics of why this happens would be good.
There is a detailed comment above this one that goes into how lower weight makes the airplane more nimble, and therefore able to apply more stress to the airframe. This feels right intuitively, but hearing it from a pilot would be cool.
Yeah I feel the same. The reason why it is not “clicking” is because he didn't explained it at all.
@@kingsizedmidget7294 I was doing some reading just now and while there's a lot of talk about critical angles of attack, weight, etc, I think distilling it down to the nature of flight helped me understand it better:
Flight is overcoming gravity. At straight and level flight, you are always pulling 1G. You are in balance with gravity because you are producing 1G of upward lift to counteract Earth's 1G of downward pull. When you start to climb, you pull more than 1G, because you're overcoming gravity. To generate 1G of lift in a heavy plane, you need a higher angle of attack from your wing than if you were lighter.
If you suddenly dump a lot of weight, your lift is going to go up at any given angle of attack (in the same way that taking off in a heavy plane will have a more sluggish climb, taking off in a light one will have a much faster climb).
So when a plane dumps a lot of water in the air while pulling some number of Gs, it will now generate more lift at that same angle of attack, which means more Gs. So what was a 4G maneuver becomes, say, a 6G or an 8G maneuver, then your wings rip off.
The way I heard it put is a heavy load will stall. A lighter load can generate more lift before the stall and thereby more stress on the frame. Think of the Va stall as a safety valve that dumps excess lift. The wings will eventually create the extra lift, but the frame can’t spread the lift. Even if the struts and spar distribute the force to the frame, now the engine mount is overstressed with its heavy load.
It’s because he’s looking at a case where the wing attachment failed, but then explains how the wing loading actually goes down. At 6:39 he briefly explains it’s not the wings that are overstressed by this issue, but the same wing loading applies higher Gs which can break other things. It’s just a bad example for the issue being explained.
Wow, what an educational video. That explains why there are several videos floating around the web showing structural failure AFTER dumping the load. Never made sense to me, but now I understand. I am a commercial pilot, helicopter, multi-engine, instrument rated, as well as A&P mechanic (all in the past, I am 80 years old). I was always keenly interested in areodynamics, and so am really grateful for your explanation of maneuvering speed dependence upon wing loading. As an A&P, I have performed the wing spar attach AD you talk about. I always liked the Pawnee 235, a very smooth and capable airplane, and a shame to see one lost. Thanks again.
I began my ag flying career flying the Pawnee and I never flew with more than 100 gallons. Never filled the hopper with liquid but we used the large hopper for dry fertilizer. I was trained at Ayers Corp. in Albany Georgia, where they make the thrush aircraft. You had to do a demonstration flight to get certified FAR 137 and part of the flight was a emergency dump. You had to learn to push the stick forward hard to keep the aircraft level cause dumping that much weight the aircraft wanted to climb like all get out.
That will tend to keep you out of trouble.
The tank looks so far from the CoG, i’m curious now what the training manual looks like for an emergency drop.
I agree. Looks to me like a rapid change in CG pitched the nose up.@@PaleoWithFries
The Pawnee pitch trim system was simple but not comfortable. A large spring on one end of a lever in the back of the fuselage attaches to a cable that attaches to the stick just above the pivot point. Moving the trim handle aft pulls, through another cable, the spring lever to tighten the spring and provide pull on the stick. Forward on the trim handle will slacken the tension on the spring and allow the nose to go down. Taking off with 150 gallons, usually the load is less for DA, will require a strong pull on the stick which the trim spring will help with. Emergency dumping with full aft trim will result in a significant pitch up unless the pilot pushes forward on the stick. The dump gate in the bottom of the hopper, also used to release dry material through a slim crack, allows slow release of liquid material as well. Liquid goes to the pump on a spray rig through a hose. The pilot may have been startled by the rapid pitch up of a full dump lever travel, fully open gate, dump. Or he may have been going for a spectacular pitch up. Or both. I personally know of two practice emergency dump fatalities.
@@gomertube I understand your comment - but a Crop Duster doesn't dump his whole load in one shot, it's sprayed in a fine mist. Which means that he's not experiencing a massive change in wing loading and Center of Gravity displacement.
Coming from a third generation ag pilot, great break down of this accident a lot of people misunderstand accidents in the ag world. Although mistakes were made, I am also leaning to the fact there was probably corrosion involved. Great job Juan keep up the good work.
Agreed. I’m imagining crumbling white spalling at the attachment.
Decades of hard work, likely living outside, previous over stress and possible neglect.
Condolences to the family(s).
Even with potential corrosion, it likely wouldn't have been an issue if the pilot hadn't pulled up so hard put so much load on the wings.
@@davidfrench5407he probably didn’t pull up. He just didn’t nose down while he was dumping. Most of the time you’d never pull the dump handle coming out of a dive and at high speed. You wouldn’t shed weight in an emergency under those circumstances in very many situations.
I started my ag flying career in an O-320 150 hp Pawnee before I moved to an O-470 Ag Wagon and later an O-520 Ag Wagon.
@@JoshJones-xd5mw from that angle he would have at least been conscious that he was heading toward a tree line. Tragic regardless of the exact cause, hopefully others can learn from this.
@@moretrash4you no, the nose came up. Did you watch the video? Juan explains it quite succinctly
Many years ago ('94-'95), as a young A&P, we had a Pawnee with Hutch metal wings that were just full of cracks. We pulled the wings to repair them and found the fuselage wing attach points badly rusted internally. They looked great with nice paint on the outside, but just ugly inside with much material missing. It left on a truck to an aerospace welding facility for replacement. Scary stuff considering how they get yanked and banked in a highly corrosive environment.
Like old houses near the sea, paint layers is only thing holding them together. I think Popeye the sailor man had a song about that
@@shable1436 we had a water tank like that at work. you knew the metal had gone through when you saw the bubble in the paint. then we used to just drill it out and stick a nut and bolt in with a rubber washer.
the glory[& FAILS] always shines on the OPERATORS/pilots but, the MECHANICS and all that attached to support their mission[s] really is so important......maybe more so [idk4sure]
OPERATORS are the ones also in the line of weather a vehicle or equipment is safe too operate.
So it maybe would[have] passed PILOT pre-flight inspection but really it is a TEAM that creates the missions capability to be a success as in returning. The total success ends with safe return.
Thanks Juan,great report w\insights
Semper Prorsum ~ Godspeed
It's fineeeee
You save money by replacing maintenance with paint.
Juan, let me add some details from my experience working as a aircraft structures certification engineer:
It is true that the maneuvering speed vA is defined by vS times the square rout of the design load factor. However, it is not a limit up to which the pilot cannot damage the airplane. vS is a calculated stalling speed (FAR/CS 23.335(c)), as estimated early in the design process. vA is a defined airspeed limitation to be used mainly for control surface and control system structural sizing. FAA AC 23-19A explains: "VA should not be interpreted as a speed that would permit the pilot unrestricted flight-control movement without exceeding airplane structural limits, nor should it be interpreted as a gust penetration speed."
The TCDS you present in this video is of a restricted category aircraft. Although limit maneuvering load factors seem not to be mentioned in this TCDS, in the restricted category certain limitations can be lowered below the FAR-/CS-23 minimum requirements, including limit load factors and structural safety margins. That is especially used for cropdusters to allow higher take off masses.
As far as wing structural loading is concerned: it does actually not change when you empty the hopper tank. Given, that speed and angle of attack stay the same. Why is that? The aerodynamic forces on the wing are unchanged as long as airspeed, angle of attack and it's configuration (flaps, ailerons) don't change. So the lift force doesn't change. The same lift force acting on a lighter fuselage lighter than before means the vertical acceleration increased, as Newton claims in his second law. To maintain level flight, i.e. maintain 1g, the pilot needs to reduce the angle of attack during release of the payload, as you explain.
It seems that the unlucky pilot in the video did the opposite and increased the angle of attack, leading to increased lift forces, which resulted in structural failure of the wing.
speed can safely max deflection of a control surface
I found this very informative, thank you. Would suggest pinning it
I was a structural tech for a while and completely agree with this comment.
Pilots need to stick to talking about flying. They also have a bad habit of blaming pilots only.
This is not the first time wings have failed in Mexico… Mexico is known for ignoring maintenance and inspections.
I’m fairly confident a properly maintained aircraft would have survived that. I see those duster fly really hard in the states all the time and no issues.
@@1KDave Did you just say 'pilots need to stick to talking about flying.'
Did I read that right?
If you go to 8:12 and change the setting to 0.25 playback speed, there's a moment right around 8:14 where you see the wing fold back diagonally. At least intuitively, it seems to me that this supports what you're saying. It's reminiscent of the silly game we'd play as kids, sticking our hand out of a high speed car and "surfing" - once the angle goes a tiny bit too high, the effect snowballs as the wing flips up and back.
I’m a chemistry guy with no aviation knowledge, but this was so easy to follow while still diving into the technical. Excellent
I used to fly PBY water bombers and we called it “checking forward” as we dropped the load. With practice, you could time it just right, so you wouldn’t even feel the load being dropped.
My grandfather flew PBYs in WWII. I was about 10 when he passed away, I wish I could remember his stories. I remember one where they ended up damaging a wing dropping depth charges
I watched that maneuver from the ground as a firefighter in So. California. The large plane was almost vertical before it passed over a ridge, dump his phoscheck and dropped straight down the 3000 foot mountain. He missed the ridge by about 50 feet. Most of the pilots back in the 80's were ex-military guys.
@juliogonzo2718 gathering of the eagles web page has some stories. Major Jack Randolph Cram (USMC), was the personal pilot of Marine Gen. Roy Geiger's PBY-5A, the "Blue Goose." On 15 Oct 1942, he won the Navy Cross and permanent nickname " Mad Jack" in operations at Guadalcanal. There's a great story of Cram rigging that PBY with torpedoes and dive bombing Japanese ships. J R Cram was my grandfather's cousin. I met him when I was eleven years old in 1967. I believe he was working in DC at the time. He had a large great Dane named Ace that my sisters and I got to play with.❤
until the day you misjudge it.....and C-130 rips its wings off.
That’s really cool. Where did you fly? I would really like to know more about pby water bombers. The old Martin mars often flew over my home as a child.
These crop dusters are loaded to cover several fields before they need to be reloaded. The emergency dump is used if you have a in flight emergency and have to take weight off of the air frame for an emergency landing.
Excellent video as usual!
As a sometimes-getting-paid-for-it aerodynamics by training Ph.D. I view this through the basic physics lens. The force on the wings is proportional to the AoA and square of the airspeed (hence the exponentially rising limit curve vs. air speed). For a given speed, at heavy weight when you pull back on the stick the airplane cannot increase it's angle of attack quickly due to the airframe/load inertia and thus the rise in force on the wings is slow. At low weight when you pull back on the stick the AoA can rapidly increase because of the lower inertia/weight and quickly get to the point of generating a huge amount of force that's trying to yank the rest of the plane upward. Ever put your hand out the car window like an airplane wing and tilt it upward a little too much too quickly and your hand snaps upwards. If your hand was made of lead it would snap upward far more slowly than your water-ish made hand. That and the heavy plane/hand was already at a higher angle of attack to counter the aircraft weight/hand weight to keep it in the air. Ever see a light paper/balsa wood airplane suddenly get too much lift it pitches up very quickly whereas a heavier paper airplane does not pitch up nearly as fast. Excellent video as usual.
Ok that makes sense. I was about to rewatch the video. I was also wondering if destructive oscillation could be a factor as the wing load drops quickly as the water is dumped then loaded quickly when the pilot pulled up?
Thank you for confirming the reason for the "low weight" limits on maneuvering speed.
This is the same reason why some friends who work as maintenance/defense contractors warn pilots to be extremely careful when flying aircraft on short ferry flights. Minimal fuel, no pax or cargo (or wing ordinance!) the jet will respond very differently than it normally does, and this is especially noticeable on takeoff as the jet will accelerate quickly, and overspeed the gear and flaps, etc. and a sudden pitch up, is at high risk of exceeding limits. Another risk for inexperienced pilots is scraping the tail on the runway.
So…as I understand it…Don’t treat an aircraft like some video game!
Or a high performance jet fighter!@@57Jimmy
Excellent explanation. Thank you, from one PhD (in an entirely different field) to another. I’m a student of aerodynamics as a hobby, especially low-speed aerodynamics for soaring and the use of negative flaps (“drag buckets”) for increasing L/D at various speeds. So this nice summary really resonated with me. Thanks again.
I don’t know why this was recommended by the algorithm but you did a great job explaining and teaching. Thank you.
Probably for me is because I’m subscribed to a channel that does mini documentaries on plane crashes and I watched one of the videos last night.
I think the video title: "PA25-235 Sinaloa MX Gender Reveal Party Structural Failure" broke the algorithm.
Great video Juan! If I understand correctly, because the mass of the load being dumped is about 80% of the empty weight of the plane, after release, the instanenous g-load is increased to 180% of the value before dumping. Thus if the plane is already pulling 2 Gs at the moment of dumping, it is now pulling 3.6 Gs the moment after dumping. No wonder things snap.
Gender reveal parties have long been over the top. Now it just seems like it's out of control.
They wanted to hire a stunt plane for their party. I don’t have an issue with that. At the end of the day the pilot needs to make the choices for safety of their aircraft. Blaming the couple for this is just silly.
Totally irrelevant to the poor technique of the pilot who made a tragic mistake and died.
Nice job, both of you. I didn't lay fault to the couple.
And they only have two colors!
Because people want to make a big deal and post it on social media. Narcissistic behavior while people die, houses burn, forests burn and people get maimed for these stupid stunts. Boy or girl who cares!!!
As a private pilot this was never mentioned to me and I was unaware that at minimal weight this could be a factor. I guess that's why they call it a license to learn. Great video.
It's troubling that your training did not cover this. If you got your license in the US, please re-read chapter 5 of the PHAK (Aerodynamics of Flight), specifically the section on "Load Factors", which includes everything mentioned in this video, including the V-G diagram.
@@owisagrom I'm a commercial, multi-engine pilot and I was never taught that Va changes with weight. I always assumed it was for the worst condition.
@@oisiaa The POH of the PA28 and C172 that I'm familiar with both publish a VA at multiple weights, showing a lower speed for lower weights. I have an extra step in my preflight planning that determines my VA based on my weight by interpolation. This is always my personal Vne
@@owisagrom I fly big jets where Va isn't really a thing. "Maneuver speed" speed for us is the speed at which we can fly a 30 degree turn with stall margin. We have a hard g limit, not Va.
There's a reason why no markings for Va are on the AI. It is directly affected by weight. @@oisiaa
Once again you did an outstanding job gathering all this info and putting it all together so we can all understand and learn from these horrible accidents.
Yes indeed. Very upsetting for the family who presumably hired this guy.
Flying fighters, we use a version of the V/G diagram to show 2 important features of performance-corner velocity (smallest turn radius which happens to match Vm) and best turn rate airspeed (faster and G-limited). If you lay two competing [Em] diagrams on top of each other, you can find your maneuvering advantage. As always, fantastic video Juan.
I've got around 7000 hours in the PA-25 235 as an aerial advertising pilot (banner towing). Our operating manual had the maneuvering speed listed (yes it is 120 MPH). I'm glad you started by mentioning the variable maneuvering speed as the weight changes. Our planes were STC'd with 75 gallon tanks where the hopper used to be (3 gallons unusable) so we had to be aware of the maneuvering speed vs weight difference as we flew cross-countries to different locations. It's a very fun and rugged airplane when used correctly. I usually called it the flying pickup truck.
Great class for all pilots. Usually, there is more than one link broken for an accident to happen, this may well be the case. Thanks Juan.
Poor guy didn’t know what he was getting into. RIP.
Your chart explains why I’m not an Engineer. All I knew was the weight changed and he stressed the plane’s limits. Thank you for the explanations.
I had a very similar response. I also realised yet again why I am not a pilot (though I am a keen armchair aviator).
Even that’s too much information for most of us.
If I follow (which I my not), by halving the planes mass and not changing it’s profile in the air, it’s accelearation from aerodynamic forces double - which if you’re pulling a 1-g nose up maneuver as you do that, you go from 1g to 2g of force on the fuselage. The wings may be fine taking those forces, but it’s going to maneuver more nimbly, and it’s going to mean 2g of force on the engine mounting in the nose.
@@Relkond thanks, thats what I needed to finally understand it.
Reducing the weight suddenly doesn't change the lift the wings are creating, but it does increase the G's the airplane is pulling.
@@Koi-Koi-Koiwasn’t paper. Was colored water. And the palms didn’t have anything to do with this.
This is a great analysis. Really sorry for the pilot and family. RIP. Corrosion will be a factor, no doubt. It's always somewhere isn't it.
Maybe, but the manoeuvre itself was pretty crazy too, I'm not an expert by any means but I would wonder how much of a difference that might make when the pilot put the plane under such forces in the first place. The wing might have snapped regardless of any wear and tear. If it is a factor, I'd expect it to be a footnote rather than anything that significantly contributed to this outcome.
These are old planes. It’s not unheard of to find cracks in the tube structure after decades of rough service
@IrishmanAC many Ag pilots pull off these maneuvers several times on a daily basis. I have witnessed iy many times here in Ohio. I feel this pilot miscalculated his load and attempted a maneuver he was used to. A miscalculated load, and a potentially structurally weakened aircraft lead to this.
@@BamaRailfan AD 95-12-01 addresses In-flight separation of wing from airplane.
@@pennhiker5117 yes, it does. Unfortunately there are those owner/pilots out there that think it'll be ok unless they get caught. Sad but true. It happens a lot in the private aviation field and really is scary.. that said, I don't mean to accuse the pilot in the video.
If you look at the still photo at 10:32 it looks like the left wing is folding up a few feet outside of the attaching point and not at the fuselage
Maneuvering speed was an area one of my instructors drilled into me. (I had three total and lost each one as they moved up into the airlines) I’ve never seen that chart before but I can say that its a great tool, especially if you want to explain why less weight will decrease maneuvering speed. I assume the same logic would apply when 12 skydivers exit an aircraft. Great teaching moment. I enjoyed the entire presentation.
very counterintuitive
The way I heard it put is a heavy load will stall. A lighter load can generate more lift before the stall and thereby more stress on the frame. Think of the Va stall as a safety valve that dumps excess lift. The wings will eventually create the extra lift, but the frame can’t spread the lift. Even if the struts and spar distribute the force to the frame, now the engine mount is overstressed with its heavy load.
@@scottmoore598best way I’ve heard it so far for me I think
Thank you for explaining this. The old C130 that lost both wings is an example as well.
I miss the good old days when the cigar ring had the blue or pink on it. A simpler time.
Yup. If you wanted to get fancy, you bought a pack of announcements at the Hallmark store and mailed them.
Or the pink and blue bubblegum cigars!
Great video Juan, as always. One detail: if you step through the video you’ll see the spar attach did not fail but the struts collapsed. First the rear (the wing twists in torsion first) then the front strut, and whole wing rotates around the fuselage about the spar attach pin.
This is again a sad story where pilots are pushed towards being a “flying circus” with a bad outcome. I will file this video for all my aerobatic, UPRT or instructor students, when I’m desperately try to explain a flight envelope. Thank you Juan for doing it for me! I like the visualisation with different colours. 👍🏻
They proberly often did flying g displays that was ptoberly their job what was this one sny different
They're the captains of their aircraft. No one is forcing anyone to do anything. If you're not comfortable with a request, don't do it. That simple.
Thanks! There are numerous Airworthiness Directives on the struts, the one you showed for the main spar attachment and another for the aft spar attach. It does not look like either of those failed. As you mentioned, it does appear that the left wing failed at the outboard strut attach point. I’ve not done crop dusting with these birds, but I do have over 600hrs in Pawnees on glider tow duty. We are about 1200# below MaxGW. You are hard pressed to get over 120mph in a dive without that extra weight.
It looks like the left wing bent backwards, causing a runaway pitch-up moment until it snapped off. That is, in the first frame where the wing flexes it looks like the wingtip flexes first, rather than at the root. You can even see the wing crease just outboard of the root.
@@michaelbigelow3255 Electrical engineer. I've never flown anything but a 172. Aircraft are mostly cool for the engineering 😄
A wing is the pitch axis , it cannot affect pitch .
Yes like a forward swept wing. I can see that. I just came across this tragic video btw.
0:17 I love how whoever is operating the camera paid enough attention to the plane to stay with it as the wings fold, but then just pans back to the soon-to-be parents as if they didn't just see what we all saw. "Screw that guy... it's a girl!" 🤔🤨
It probably didn't even register in their mind what just happened. That plane was literally flying by. 100+ mph. They just swung the camera back behind them and then right back to the over-spending, braggadocios couple.
Aye, I suspect they didn’t process what was happening and just swung back to the couple on instinct.
I doubt very seriously that anyone was aware of the tragedy that just happened. I would love to see video of the next 5-10 minutes. My guess is that the mood changed drastically once reality sank in.
The first clue that the person making the vid has no idea what they’re doing is the vertically held phone. It goes downhill from there.
They were watch the video of it right when the wing bends there is a terrified high pitched scream followed by a glimpse of people running away towards it, people were absolutely aware of what happened the second it happened and the cameraman had a perfect view so put two and two together
Dumping the hopper causes an extreme nose up trim, it will take you by surprise if your not ready for it. A massive push on the stick is required during the dump. I am guessing he was a banner or glider tow pilot, not an ag pilot.
Not in a Fletcher - the hopper is right over the wing - relatively neutral compared to forward hopper planes like Pawnees and AgWagons when dumped
Thanks, that fits much better to what the accident video shows than Juan's explanation.
Reducing weight (e.g. by dumping cargo) while in a turn with a constant wing-loading will increase the g-force on the aircraft, which can cause structural failure. But in that case it wouldn't be the wings that fail, those are at a constant load as we said. What would fail are the "fixed weight components", i.e. the high gees would rip the engine off its mountings or so.
What happened in the accident video was that the aircraft pitched up massively as the hopper was dumped. As Juan explained, at lower air-speed that would have led to a stall instead of a structural failure, but I don't believe the pilot intended to put the aircraft into a stall so close to the ground. So an unexpected change in trim that caused the nose to pitch up is a more likely explanation.
@@DrAHorn The final picture in the video is stopped at exactly where the wing failed. You can clearly see it twisting as the attachment point failed. So the wing was fine. Just it decided to go one direction and the body another. With a poor couple of bolts left somewhere in the middle.
@@josephoberlander Well, O.K. it may technically not be the wing. But it's still part of the structure that is engineered to support the full force that the wings can carry.
@@DrAHorn True. It does look like it failed a bit earlier than it should have, but such are old machines. A little deformation, a loose bolt, a bit of rust and it could be still up to spec but just barely/needing replacement soon. It will get interesting to see what the reports say about the condition of it and the maintainence recrords.
Aero Engineer here with a lot of ag design/testing/certification testing..... When you emergency drop, the effluent drops down entraining air which increases the angle of attack at the horizontal tail which increases the down force at the horizontal tail. This tends to pitch the aircraft nose up without any input from the pilot. A number of AT-802's have been lost because of this phenomenon, but in this case the horizontal tail stalls and the aircraft bunts (uncontrollable nose down).
I think you have the answer sir. After watching the video frame by frame it appears the tail got sucked down by the water down wash coupled with sudden wing unloading. Maneuvering speed has to do with full control deflection limits, as I recall from ground school.
While it is true that low weight does increase max Gs for the same control input at any given speed, the lift of the wings and so the couple at the wings roots is the same, so I don't see how low weight can be to blame for this kind of structural failure. Other parts of the airframe indeed are more stressed with more Gs, but not the wings because of this low weight situation. Thanks for your response, it meens a lot for us GA pilots your videos. Congrats.
Lightly loaded, the wings can produce more lift before stalling because it has more available angle of attack.
The way I heard it put is a heavy load will stall. A lighter load can generate more lift before the stall and thereby more stress on the frame. Think of the Va stall as a safety valve that dumps excess lift. The wings will eventually create the extra lift, but the frame can’t spread the lift. Even if the struts and spar distribute the force to the frame, now the engine mount is overstressed with its heavy load.
Unfortunately, I could not wait for today's class. Once again you did a stellar job. Sir, you save lives with your channel. Sorry for the pilot and his family. RIP young man.
No he doesn’t tell me how he saves lives the NTSB saves lives not this clown
That was the best explanation of the danger of exceeding normal or lower Vp I've read or heard. Thanks Juan!
It's amazing to me the lengths ppl will go to reveal a gender of a baby. Pilot killed, wild fire started and so on so on. Call or text your friends it a boy or girl. Ppl died because of this nonsense, enough all ready
Monkey see, monkey do... it's rampant.
When an aircraft manufacturer has a bit of a reputation for wings occasionally folding up unexpectedly, keeping any unnecessary wing loading out of a drop like this seems like an even more crucial, basic safety practice even without the corrosion factor being known. It's not just ag sprayers or GA that have to face corrosion risks head-on, either. Airline aircraft deal with corrosion issues as well, and the manufacturers have their own specialist "corrosion gods" who get to know the issues seen in the field, and their remediation, in great detail. Boeing had quite the send-off a few years ago for their retiring master of the subject who spent lots of time deep in the structure of 747s (esp. under lavatories and anywhere condensation tended to form), and even in their fuel tanks where organisms would live feeding off the jet fuel and creating issues in tropical climates, particularly.
One thing doesn't track for me - yes, the g-load increases when dumping weight and keeping airspeed and angle constant, but g's don't break metal - Newtons do. And while we usually think in g's because the force comes from inertial loading, in this case the force exerted by the fuselage on the wings didn't increase - the only force trying to tear off the wings was still just the constant lift.
(What could have changed was the distribution of forces inside the fuselage, and slightly in the wing itself).
I am more inclined to believe that the CG moved aft abruptly and the aircraft pitched up, increasing lift force on wings and thus causing a break.
Really great breakdown, as soon as I saw the crash video a few days ago, I thought "I hope Juan makes a breakdown video on this crash".
And they didn't even see the aircraft breaking and crashing and just continue celebrating! 😡
Was looking for this comment.
Though it seems that one person actually did and ran towards the crash site.
I'm sure they didn't celebrate for much longer, after realizing the plane had crashed.
It was in the video, someone should have noticed. Or heard.
I could not believe that no one, or almost no one, noticed the airplane come apart and crash.
@@flightsimguides The cameraman noticed and didn't give a shit
I used to fly the Pawnee (later the Canso) spraying in Africa, in the 70s. It is now a nostalgic chapter of my life and I found this video both illuminating and sad. Thanks Juan, you ALWAYS produce such high value information. Pilots would do well to follow EVERY ONE of your videos. Thank you.
Also the modified wings from round to square wingtips may have a big impact in twisting moment on the wing structure? It seems that the wing starts to fail by first being twisted and by then all structural integrity is kind of gone..
This could also be a lesson about the possible impact of modifying aircraft and the importance of verifying tests. As others have stated about the wing attach fittings, I did a reinforcement on a tug-Pawnee here in Sweden some 10 years ago. The Pawnee look rugged by the looks, but in my opinion is a pretty weak construction. At least the part forward of the cockpit. thanks for a great channel Juan! You have a nice way of explaining 👍 greetings from Sweden 🇸🇪
Why would the wingtips be modified, from round to square? My thoughts are that this aircraft could be used for "events" and that the square tips used be used to accommodate smoke canisters. Also no doubt is pink and blue flavours.
This is a remarkable presentation from Juan Browne and I will surely pass the message to our club members here in Alsace (France). Thanks 👍
Grandma killed by shrapnel, massive wildfire and now a dead pilot. How about just saying "it's a boy".
Thank you for covering this tragic loss. You have given me a good understanding of what went wrong
Juan, as always a spot on analysis of a tragic event. I have great respect for your aviation knowledge!
I'm not sure if you know, but when a UA-cam video is paused you can use the greater than less than keys to move one frame at a time. I find it useful on many videos when trying to see something important. Of course the quality of the freeze frame depend on the quality of the video. Cheers!
@EmesiS - Thank you! This reminds me to search for an instructional video for using UA-cam. And if you use the period and comma keys, the increments are much shorter.
@@StevenBruce-s1o Lol...well that's basically what I meant. Same keys, I just always say greater and lesser instead of comma and period. I didnt even think about the difference when I posted....duh. if you do hit shift, that changes the speed and not the frame increments. Anyway you figured it out....cheers!
@@EmesiS Oh, thanks! I'll try that out!
Dear Juan as an engineer i am not sure I agree with your explanation. Dropping weight before/during the pull up actually reduces the load to be carried by the airframe. So the drop is not the problem in my opinion but the sharp pull up that exceeded the limits of the wing. The CL215s always do sharp pull ups during the drop while fighting fires. Just my two cents and greetings from Athens.
Even though it reduces the load it increases the amount of G force being applied on the aircraft for that moment as the weight of the aircraft suddenly decreases. Kinda like if you were pushing an object and object suddenly moved so you fell forward...except with lift. There is less aircraft weight to be lifted causing a bigger spike in g force for that moment in time.
Currently working on my Bachelor Thesis about fatigue damage in aerial firefighting. This video including the comment section is great! Thank you all :)
I had seen personally three of that aircraft in the early 70's where the tubing next to the tail wheel was corroding apart from the chemicals, speaking of such, why would anyone, especially pregnant, want pesticides and defoliant tank water to be dropped on them???
Anyone who wants this kind of nonsense for a 'gender reveal' probably has a IQ so low that they struggle with any concept above 'Whoo pink pretty stuff'
I thought the same thing.
Probably cartel members... not exactly geniuses.
Mexicans dont care we should let all if them into our country NOT
As I recall… during the low level skip-bombing assault on the Ruhr Valley Dams during WWII, 5 of the 8 attempts resulted in loss of aircraft to both defensive gunnery and catastrophic structural failures.
One of my favorite movies as a kid was "The Dam Busters".
I have a small 2x2” piece of “AJE” , a Lancaster lost on the dambusters mission, AKA “operation chastise” … flown by Flt. Lt. Norman Barlow and his crew, lost to ground fire at 23:50 hrs May 16-17 1943… Godspeed boys…..
Nice reference!
Only one aircraft was lost over the dams, that happened at the Mohne dam. It pulled up but one wing was on fire and it broke up and crashed. The Eeder dam did not have defences. The aircraft that had to attack that dam all pulled up very steeply but none broke up.
@@chriss.4147 He could be talking about training / testing too. There's film of a least one where the bomb bounced into the tail and the aircraft went straight into the sea.
Dying fighting fires or some other practical function is bad enough, but dying for something so utterly ridiculous and pointless is even worse.
$$$
So dying is worse than dying.
When flying the wing generates lift which causes the wings to bend upwards. The weight of the aircraft causes the wings to bend dowards. This is called G relief. The heavier the aircraft the greater the G relief. If the weight of the aircraft is suddenly reduced the amount of G relief is also reduced.
This can be seen launching gliders by winch. As the glider climbs higher the force pulling the glider down increases as the angle of the cable gets steeper. During level flight the Vne of an ASK-21 is 151 kts the maximum winch speed is 81 kts. (All the other numbers in the VG graph will change pro rata). This effect is most noticeable when winch launching long winged gliders such as the ASH-25.
Great reminder to all of us sir!! Some aircraft are more susceptible than others. I loved the way you went back to the basic chart to reiterate how dangerous exceeding design limits can be!!! Thanks again Juan!!!👍
In the first clip it seems the party attendees didn't notice the crash...?
Sad indeed and well done Juan.
The most eerie thing in my opinion is that the person filming definately noticed but filmed back to the couple as if it didn't happen. Like they didn't want the plane crash to ruin the day.
@@TELE6220 definitively
its a somewhat common response to some types of traumatic events. almost as if the brain just overwrites that portion of memory to avoid dealing with it.
always creepy to see though. people dying and everyone just going about acting like its not happening
Like "Oh the plane just had a huge structural failure and the wings ripped off...it's a girl, yayayy!!" :/
@@kekke2000 "he person filming definately noticed "
The phone follows the plane past the point where the wing broke, but that does not mean the person holding the phone was looking at the phone or the plane.
I was trying to explain to maneuvering speed to a student pilot the other day. This was a grim demonstration of its importance and the results of exceeding it.
I didn’t recall the issue of how changing the A/C load effects maneuvering speed. Thanks Captain.
I love watching videos of someone telling me what I can read for myself
What a tragic event, that was supposed to be full of joy. My deepest sympathies go out to the family and friends of the pilot.
I just can't relate to people who do stuff like this. I guess trying to do something cool and memorable trumps good sense. A flyby with a plane is cool and I've seen things like this done with skydivers and it makes no sense. It's cool if it all goes well but look at the penalty for failure!
It looks like they were still celebrating even though they literally watched the plane break up directly over head. Maybe they thought the wrong falling off was part of the show?
@@Skank_and_Gutterboy Everything has to be on Facebook even the morning bowl movement.
Juan, I love how can you be such an aviation nerd AND help us fellow aviators with your experience, research and insight at an understandable level. Keep 'em coming, and come visit us in Idaho again sometime!
So the person filming the accident follows the plane up until the wing breaks and the plane disappears from line of sight then turns the camera back on the couple hugging and keeps it there like nothing ever happend? RIP to pilot.
Thanks! This is a valuable lesson....one that I've never heard before. My initial intuition was wrong regarding Va.
Great job Juan. Wouldn't we say a wing has two critical AOAs? The positive AOA, and negative or inverted AOA? Probably not too relevant to this video however. Nice work.
Hey Blanco, when the water is dropped rapidly, remember the wings were making 3,000 lbs of lift but the aircraft now weighs only 1,600 lbs. The airplane climbs violently, sometimes exceeding the available down elevator.
I'm no expert, but this doesn't sound right to me. The wings are placed at, or even slightly behind, the center of mass of the plane; so even with the large discrepancy between lift and weight, it doesn't have a significant moment arm to operate around, and if anything, with the wings behind the centre of mass, that would create a slight nose-down torque upon release -- but regardless, the tail fin is there to keep the plane flying generally straight. So I think you're confusing linear forces with torques. I mean, the plane can fly straight and level when full, and can fly straight and level when empty. It's just a angle of attack change to move towards those two regimes.
@@TheHuesSciTechThe tank in that Piper looked to be forward of the natural CoG, mounted in front of the pilot like that. The dump probably moved the CoG backwards a bit, and did so suddenly. Given the likely strong nose-up trim required at maximum weight, even a small movement of the CoG could induce a strong pitch moment if the pilot wasn't ready to counteract it.
@@TheHuesSciTech it has nothing to do with CG. Presuming everything is in equilibrium, trim is set, the horizontal stab is neutral or pulling down slightly and the wings are making 3100 lbs of lift to carry the 3,000 lb gross weight straight and level. Now dump the 1,500 lb load in about 3 seconds. The airplane will pitch up violently, not because of any change in cg, but because the wings are still making 3100 lbs of lift but you only weigh 1500 now. Try it sometime...ag pilots are accustomed to taking 20 or 30 minutes to empty their hoppers, not 2 or 3 seconds. Best of luck, and be ready with ALL the forward stick!
Great analysis and explanation of this mishap Juan! Thanks for bringing us this great content.
I’m probably in the minority but I think that gender reveals are a stupid, look at me act. I remember a few years ago at least one of them started a forest fire that burned multiple houses to the ground. Why don’t people just wait until the child is born and announce its gender then?
I confess, I am confused by this explanation.
A stable aircraft will trim at a lift coefficient. This, when the load is dropped, assuming it is on the CG, the aircraft would pull g to maintain the lift coefficient. There would be no effective load change on the wing.
But! If the load is in front of the CG, you would get a trim change increasing lift coefficient … is it possible this has nothing to do with VN and everything to do with sudden trim change unexpected by the pilot combined with a pull-up?
Juan,
you did a great job treating this seriously…
Very professional,
no stupid joking around.
“Just the facts,Ma’am.”
-Sgt. Friday
This is why I'm your patreon! You are able to explain short and clearly, whatever may be intrincate and hard to pick up from harsh or sad events like this!
Thanks for your support!
06:17 - Yes, but it's not the wing loading or "X" pounds of lift that break the wings - it's the g's. On the examples given the g's are fixed at 4. It takes an "X" amount of g's to break a wing, at whatever wing loading or lift force. At a lower wing loading the wing may not stall (which would unload the wing) before reaching its design g-load factor and may break, hence the lower maneuvering speed at lower weights.
Correct! You got it!
It's a bit more complicated. The limitations are given in "g"s because it is an easy to express limitation. However, when you change the masses configuration of an aircraft there are changes in the forces, some forces increase, some decrease.
In this case, if you unload a fuselage-mounted tank, the wing attachment forces decrease while the fuselage structure (engine mounts in particular) experience greater forces for the same angle of attack. That's why manouvering speed often decrease with weight.
@@blancolirio I’m not sure he does have it correct. The lift the wings produce depends only on airspeed and angle of attack. In your example if the 16000 lb airplane pulling 4Gs suddenly releases 8000 lbs of weight it won’t be pulling 4Gs anymore it will be pulling 8Gs unless the pilot lowers the angle of attack to reduce the lift. An aircraft that drops weight at constant angle of attack is likewise going to accelerate upward and climb without any pitch input from the pilot.
So that’s what likely happened in this mishap. The pilots 2-2.5 G pull-up became a 4+ G pull-up as the water was released overstressing the airframe in the process. This would have been exacerbated if the aircraft was above maneuvering speed.
Amazing how everyone saw the wings fold and the plane start spinning but didnt miss a beat with their task on the reveal or miss the shot.
Right, was wondering why no one else had pointed this out! A guy plumetting to his death... Pan back to the choreographed reveal hug. Lost a little more faith in humanity...
THis has @@worldwideflyby prompted much reaction. BUT I highly doubt they really seen what we did in a post flight event w\video review...think about it
PERSPECTIVE → point of view[actual] then also add in SPEED & flight altitude & then window of visual [time] before out of.
SemperProrsum~Godspeed
Excellent Training! Thank you Sir! I've been around a while and Never really thought about this Operating situation! Totally was the Factor here! As I think about it, I'm thinking the Pilot should have realized this if he had extensive experience Operating as an Ariel Applicator! I'm wondering how Many Drops of the nature he had Performed! Ya, lack of experience probably was a Factor here! I'm thinking a experienced Operator of AG Aircraft would have made a Normal Drop without a Hugh Pull Up Maneuver! God Speed too this Pilot! This accident and it's analysis may help save other Pilots! Great example of Accelerated Stall Possibilities! Thanks again!
Excellent video and clear explanation. Pilots do not understand manoeuvring speed and how it changes with weight.
Thanks for the insight Juan. It only takes one mistake to pay with your life. Simply put "small corrections" That's what my Dad would say when I was first learning to fly as a kid. I was a career pinch hitter with my Pops you could say. Every flight was a learning experience :)
I see you are still alive.
@@tedmoss It worked out, only crashed once which was no fun.
Great explanation. I've never even seen a V-G diagram before, so this was all new material for me. I wish you could have shown us a modified V-G diagram showing the unloaded state for comparison. My only complaint (albeit a minor one.)
Counterintuitive... yes! I definitely learned something today. Your analysis videos and commentary on real world events are extremely useful and educational.
Nobody better to comment on aircraft occurrences than an experienced pilot.
Thanks again!
I fly SEATs and I can tell you that the airplane does pitch up when the load comes off. If you ever watch a cockpit view you’ll see the pilot push the stick forward (full forward for a salvo). I think the pilot wasn’t ready for the pitch up, was well above ideal drop speed, and the rapid increase in G’s caused structural failure. Keep in mind that the wings are producing around 2900lbs of lift at that airspeed and pitch angle. When the plane loses, let’s say 1000lbs within a few seconds the excess lift causes the plane to pitch up rapidly. If you aren’t ready to counter that with forward stick, you will find yourself behind the plane. This tendency only increases with speed.
Thanks a lot Glenn. An extremely clear lesson on structural limits. And the difference between an oooold crop dusting utility aircraft (turned into a light firefighter aircraft) and an aerobatic aircraft…
I wonder how the child will feel about this when she grows up.
I'm sure the child will never know.
Thanks for the video.
I always thought that the point of a crop duster was to release chemicals in a very slow, controlled way. I understand that the fire suppression planes need to make a hard drop at once, but I thought crop dusters were made for a different kind of use.
That's correct, this kind of drop was meant to be for emergencies only.
Yes, normal operations of crop duster would release small amounts over time, however as explained in the video there is an emergency release which was used here.
I wonder if the pilot was qualified as a duster pilot. I would guess that this scenario would be covered in training.
@@guntherberger596 I remember him saying that there was an emergency release. I wonder whether the manufacturer established conditions under which the release should be used. For instance, if the engine fails and the plane is going to crash anyway, I can see value to releasing the chemicals so that a rescue doesn't have to deal with the chemicals. I wonder whether the "owner's manual" for the plane basically says that if one isn't crashing already then using the emergency release is likely to cause a crash.
This has happened before, a few years ago, at a wedding I think. A family member flying. Tragic. Can't remember where.
There are too many examples unfortunately. April 2021, 2 people died crashing into water after a gender reveal stunt in Cancun. November 2019, a pilot survived a crash after dropping pink water for a gender reveal in Texas.
@kekke2000 Really unbelievable. And I must be really out of it - I had never heard of a gender reveal party. We used a cute mailed announcement. Or nothing. I'm sure mail changed to email. But a pink water dump? 🤷♀️
It seems likely corrosion and the famed weak Piper spar figure in this somewhere. I remember the Piper arrow wing failure in Florida and the Cherokee Robinson helo midair with that spar failure, both a few years back.
lower weight causes lower safe manoeuvring speed because ? You can pull more g load with full control input when the plane has a lower mass?? Did I miss that exact correlation take away from the graph ???
Suggestion - attach smoke canisters, approach with white smoke, switch to pink overhead, fly tomorrow.
Ride a motorcycle with training wheels.
Our gender reveal was 20-30 homemade cards mailed to friends and family. I’m sure they spent more time looking at the cards than these party guests spent pondering an associated death.
I’m sure some of this is due to people’s wide-ranging ignorance these days. Some of the Wings over Dallas phone footage captured people asking whether all the aluminum falling from the sky was part of the show.
As for this crash, it’s pretty close to call, but it looks to me like the wing was already tweaked before the rapid nose-up.
Thanks for being responsible 😂
I dislike gender reveals so much, that was something never happened years back in my country, now the people has to mimic the stupidity from other countries... Jeez
I appreciate Juan's thorough explanations. But I too wonder if that wing folding up like that was inevitable after enough instances of similar abuse, regardless of load dumping.
For each of our three the gender reveal was after the birth, the doctor told us the gender of the baby and when we showed the baby to family and friends we told them the name and they figured it out. At every doctor appointment we had to tell them, we don't peek at Christmas presents from December 25th and we don't want to know the gender!
Gender party give me a break let me explain how gender works if have a penis your a guy if you don’t your a woman simple as that
Indeed... Many unfortunate things revealed during such a tragic event. Thanks Juan.
The G-bend limit on this diagram, is the horizontal line at a constant G.
It does not change with speed.
What changes is the stall speed, which increases with airspeed and with G.
R
Wow this was an awesome assessment and breakdown. I never knew the dangers that those fire planes are in when dumping a load. I couldn't image how difficult it would be to drive my car if I had to worry about speed, g-forces and weight to keep my tires on when going around a corner.
I imagine you're doing that intuitively in your car but such lectures wouldn't hurt for drivers-ed classes.
Not exactly. You couldn't tear the wheels off a car by turning sharply. You would either start to skid or roll. I am talking about operating something that is very fragile and you can destroy by fairly normal operation. @@StevenBruce-s1o
Sad case. Wonder what the service records show on this aircraft. Thank you for the, as usual, valuable insight.
I'm just wondering how much Ag spraying experience the pilot had... thinking not much.
Wouldn't have even thought that dropping something (heavy) from an aircraft would be legal, outside of some exceptions like agricultural or fire fighting activities.
Far better to release colored smoke or something like colored confetti/chaff
Exactly!!! People don’t think, is everyone more idiotic by the day?
@@BrainWasherAttendent Yes.
It’s legal (in the US) as long as you make sure it won’t harm anything on the ground and you have landowner permission, etc
But low altitude dropping over a crowd in the US would probably be a quick license pull
@@BrainWasherAttendent Yes they are.
It's been done before. But narcissistic parents always want to one-up their reveal parties.
The fact that they still kissed and celebrated right after the plane crashed was the most insane part of the video.
That “ahah” before the Argentinian reveal was peak dad joke reveal.
Love you Juan. Keep the content coming!
Early Pawnee ‘s had wooden wings which have broken. Most were updated to aluminum. We used them for banner towing as some companies still due. That could have happened here.
Is it possible that this emergency dump imposes a transient dramatic shift in the center of mass too, that contributes to that large nose-up rotation?
My thoughts as well. He is essentially dumping over a half ton of weight from the nose of the aircraft in less then 2-3 seconds. Seems like that would cause a CG shift, that maybe he tried to counter too much?
I think the hopper is on the CG so shouldn't have a shift as it was dumped all at once
I'm leaning towards structural failure from either pass flights or an ongoing issue that was unnoticed. That plane should not have failed during a simple maneuver like that.
@@flyinbryanfpv even if it was perfectly centered on the cg of the airframe that much weigh loss in that time frame would cause it to at least "balloon" up a bit. Which the pilot might have tried to counter with forward stick. Which would have been bad idea. I am not saying I know any of these things to be fact, just stating my own point of view from the video provided. It could have been coupled with a problem airframe as well. Just a bad way to go and for no good reason.
@omegawolf81 I agree with you. The part I was addressing was the possibility of cg shift being the cause. Its more likely the sudden loss of 1000+lbs of water and pilot input causing the catastrophic failure
Imagine you successfully dump your pink only to lose a wing and in less than a second you know you’re screwed. But in that moment you see the couple hug and kiss in perfectly coordinated love and joy just as you go in.
I wonder what last thoughts you might have in that moment. I wound hope the pilot saw the joys and love and smiled knowing he’d successfully completed his mission, or if he never saw anything because of adrenaline dump and disorientation ahead of impact. It’s such a strange scene as it has birth and death, joy at love and birth and a flaming end and violent lonely death.
he he he, dam bro I think ya nailed it !!
As an operator myself, I thought about things & came to same. Mission first pilot thoughts ha agreed!
You mention on the air tablet the water/retardant tank is centered on the air frame. On the accident plane you said it's toward the front? Could that have created a seriously or of trim nose up configuration?
I have always loved aircraft but I am not a pilot. This is an excellent reminder to me why I should never try to fly. The details that must be remembered around the weight, G-force, stall speed, etc... are not my strong suit. Would love to be a mechanic again, but you guys that are (good) pilots get all my respect.
wow I never thought about it, counter intuitive and scary.. of course I never had the option to dump all my passengers out the bottom of the aircraft and yes I have had my mother-in-law in the back before :)
😆I know the content was not funny but your comment is. Very.