@@SoundShunter72 yep. As a non pilot I Couldn’t sleep until I acquired this useless information. But next time I’m around some heli pilots and they start up on some servo saturation I’m on it.
@@SoundShunter72 I’ve done those. Pretty cool. I’m not a pilot but I fly all the time. I work for rich dudes with all kinds of aircraft. The Texan T6’s and Boeing stearman are my faves. I flew in a lot of blackhawks in the military too.
I think you are looking at the issue incorrectly. There is never a situation in which you should be flying in a manner where you could get into servo transparency. Period. The airframe holds you in the air. It holds your life with in. Should a helicopter be able to perform a barrel roll? If the helicopter can not would you consider that helicopter unsafe to fly because you could not perform said barrel roll?
@@EUROSAFETYTRAINING and a need to suddenly avoid a collision such as a possible mid air, and not being able to avoid it cause it might bend the airframe means y’all gonna crash. What a great safety system. (Sarcastic).
@@cfdfirefighterthey surely weighed the trade-offs and determined that this was the safest option. It's probably riskier to allow pilots to override the system, because then they might get too complacent. Either way, rather than making assumptions, it's good to look up this kind of thing to alleviate any sort of concern you might have.
@@R2Bl3nd the F-18 has an override to allow higher than rated G’s on the airframe. Seems like they could include that type of switch, and training on how/when to use it.
@@cfdfirefighter yeah it's certainly worth questioning why; it could absolutely be just a cost-saving measure that's decreasing safety. It could be that they put the upper limit high enough that you wouldn't ever want to push it further; I'm not an expert but I would guess that with helicopters, any amount of bending could potentially lead to a fatal catastrophic failure, just because the power distribution mechanics are so intertwined with the airframe itself, as opposed to being almost entirely self-contained in an engine on a plane.
GM had a problem on the X bodies where the rack and pinion passages would start to plug up and resist flow. With a yank of the steering wheel, system pressure would exceed the pop off of the power steering pump and the steering wheel would lock up. Easing off would restore function, but by then you already ran into a telephone pole.
Thank you for bringing up this interesting case with GM's X bodies. The issue you described with the rack and pinion passages getting clogged, leading to a sudden lock-up of the steering system, is indeed a serious concern. It highlights the importance of maintaining proper flow and pressure in mechanical systems, much like the servo transparency issues we discussed in the video. Of course the difference is that the GM issue was a failure within the system and servo transparency is reaching the maximum force of what the servos can apply. In the case of GM’s X bodies, the sudden increase in system pressure overriding the power steering pump's pop-off valve demonstrates a critical design consideration. It's a stark reminder of how mechanical failures can have immediate and dangerous consequences, as you mentioned with the steering wheel locking up unexpectedly. Within servo transparency the lock up is achieved through a purposeful application of force on the rotor system. Thanks for sharing this example, as it adds a practical dimension to our discussion about the complexities and challenges in mechanical and hydraulic systems.
I absolutely loved flying 🪽 the AS 350 B2 👍 🇺🇸 Never experienced this. I have accumulated more than 25000 hours in helicopters 🚁 and all I can say is; every single one of the types I've flown has limits. Just like all machines. Know the limits, including your own.
Hey Glen, maybe you can give some insight about the dual hydraulics + increased internal take off weight on the AS350. Is it correct that one theoretically would get into servo transparency earlier in a helicopter with dual hydraulics(35bars) vs. single hydraulics (40bars) and even earlier in a dual hydraulics while using the increased internal take off weight? Is this the reason why there is a Limit light on the dual hydraulic system and not on the single system? Thanks in advance!
I think it would be best to lower the green area on the airspeed Indicator to 120 max then from that to 150 a yellow color to remind pilots of the situation.
Mentioning "canyon walls" reminded me of Sundance accident (NTSB Accident Number: LAX03MA292; AS350BA, N270SH). A pilot of Grand Canyon tour helicopter, used to perform thrill rides, including flying at Vne and extreme pitch and roll angles. Servo transparency was considered and discussed in the report, but finally it was ruled out. I'm not going into details, but it shows, that you have to work for the transparency to manifest itself, usually by breaching several limits at once. Another thing is, people seem not to be bothered about the possibility of mast bumping in a Bell or Robinson (there is at least one video on YT, that shows it almost happening) or Kamov's rotors intersecting each other, when flying slightly above Vne. These are not flaws, but part of the design as even the best ones have their limits. One can damage or even break a jetfighter or aerobatic plane, with a gross misuse of controls.
"servo transparency" - what a lovely euphemism. How about "servo saturation", or perhaps "servo inadequacy". If it was really a question of preventing damage to the aircraft, there would be an indication of approaching saturation - either audible or visual.
@@EUROSAFETYTRAINING Maybe true, but manufacturers have a moral obligation to make their aircraft as forgiving as reasonably possible. I've had jack stall demonstrated to me a few times (I don't have a lot of squirrel time) and while it was definitely an abnormal flight maneuver, i wouldn't say that it's outside of the realm of possibility in some conditions. It's easy to pass the blame onto the pilot, but if there's one thing we know for certain, humans make mistakes. A slightly higher tolerance could save lives.
To put is very simply, there is absolutely no reason to fly a helicopter in a manner in which you can experience servo transparency. It would be akin to saying that the 737 has a deign flaw because you cant do a barrel roll in it.
@@EUROSAFETYTRAINING a fairly basic steep turn will set the limit light off in an as355, are steep turns barrel rolls ? Your argument is similar to Robinson’s argument against mast bumping, and it’s a bit of a cop out. At the end of the day human error is guaranteed, and the best human interface designs (for anything technical, not just helicopters) will be forgiving to that error. Good training will reduce the error, a better design will eliminate it, which will save more lives ?
Thank you for your insightful comments about the technical aspects of helicopter operations, specifically in reference to the incident with the 355 model in St. Petersburg. While the maneuver might seem normal, a closer examination of the pitch and roll parameters reveals they are quite extreme, something I'm sure you'd agree is not advisable for safe flying. I concur with your point on human error. However, flying a helicopter recklessly is a deliberate choice, not just an error, and is undeniably dangerous. Regarding the technical specifics, the hydraulic pump on this model can indeed handle pressures over 1300 psi, though it's regulated to 580 psi to avoid damaging the rotor system during flight. I believe the discussion should focus on whether a complete redesign of the rotorhead is more beneficial than merely adjusting the hydraulic pressure. I hope my response doesn't come off as dismissive or similar to Robinson's style. My aim is to engage in a constructive and technical discussion about helicopter safety. Looking forward to more such engaging exchanges!
It would be interesting to know what the difference is between the maximum force that the servo allows to be exerted on the aircraft and the force that the engineers designed the aircraft to be able to withstand.
The concern is the long term health of the composite rotor system. There is not a helicopter made where the manufacture publishes the breaking point force of their rotor system.
@EUROiSAFETY do you think it would be feasible to design the aircraft in a way whereby when the pilot reaches the point of servo transparency happening, instead of completely preventing further input to the controls it will instead sound an alarm and stiffen up the controls significantly so it requires effort to move them beyond that point but it allows it to happen if the pilot really forces it? It seems that when this happens the aircraft is going to crash anyway, so might as well give the pilot a chance of recovery. Then once the aircraft has been pushed beyond the limit it must have the parts replaced that endured the extra stresses before its next flight.
Let make this discussion simple. The RFM states... In the limitation section....The following are forbidden: - Aerobatic maneuvers. The Federal Code of Regulations state.... § 91.9 Civil aircraft flight manual, marking, and placard requirements. (a) Except as provided in paragraph (d) of this section, no person may operate a civil aircraft without complying with the operating limitations specified in the approved Airplane or Rotorcraft Flight Manual, markings, and placards, or as otherwise prescribed by the certificating authority of the country of registry. You should never be flying this helicopter in a manner where you will ever experience servo transparency. Period.
@EUROiSAFETY oh I absolutely agree. I think perhaps there was some misunderstanding in what I was saying, because I was not for one minute implying that people should fly in a reckless manor. But nevertheless it is evident that sometimes some people do push it too far, whether on purpose or not. Even the guy who flew the prototype of the 747 barrel rolled it twice in front of everyone. It doesn't mean they deserve to die by default though, along with all their innocent passengers, when they could potentially have been saved if only the servo allowed them a little more power at a critical moment though does it?
I apologize if I seem blunt or dismissive. My frustration likely stems from the difficulty in conveying what seems to me a straightforward concept. Many have commented on the video, suggesting that the hydraulic pressure in the AS350 should be increased. However, this overlooks the purpose and potential consequences of such a change. For instance, while it's true that the pump can generate over 1300 psi at 390 NR, increasing the system's pressure isn't a simple task. Doing so would require the helicopter to undergo complete recertification because this change could affect all components. Moreover, past engineering analyses have shown that increased forces in the hydraulic system could strain the rotorhead. This implies that a complete redesign of the rotor system might be necessary. Consider the expenses involved in just these two adjustments. The costs would likely run into millions of dollars, driving up the helicopter's price substantially. Consequently, the helicopter could become too expensive for its target market, leading to a decline in sales. Such a significant investment and potential loss of business, just to accommodate the demands of a few who wish to operate the helicopter in an inadvisable way, does not seem like a sound business decision. The addition of dual hydraulics to the helicopter led to a noticeable decrease in complaints about servo transparency. This change, however, was misunderstood by many. Contrary to popular belief, the introduction of dual hydraulics did not increase the system's pressure. It seems that the mere thought that the pressure had been increased was enough to silence the complaints. This suggests that the issue may be more about perception than actual mechanical shortcomings. If people believed that the problem was resolved with the new system, even when the pressure remained the same, it indicates that the original concerns might have been more psychological than technical. If the system were to operate under higher pressure, the manufacturer would bear the responsibility for any resultant damage to the airframe. In a legal scenario, the argument might be that if the pressure is available, pilots should be permitted to utilize it. This places Airbus in a precarious, no-win situation. Additionally, there seems to be a widespread misconception among pilots regarding the likelihood of encountering servo transparency. Except in cases of exceeding VNE, it's highly unlikely that many pilots have ever experienced it. Even among your acquaintances, it's improbable that anyone has felt it. On the off chance someone has, it's likely that they're known for unconventional or erratic flying styles. The hydraulic pressure in the AS350 is more than sufficient for even the most intense flight maneuvers. In every instance where servo transparency contributed to a crash, the pilot's conduct was extremely reckless. It is not, in my opinion, Airbus' responsibility to cater to the whims of such pilots. If I ever believed there was a genuine issue with the system, I would be the first to voice my concerns loudly. My previous videos have been candid about various helicopter components when problems arose, proving my impartiality. However, I firmly believe that the hydraulic pressure in the AS350 is not a concern for professional pilots who operate the aircraft responsibly.
Hi, congratulations for all your descriptions, which are truly fantastic, I wanted to ask you, is there any school program or software that indicates all the faults, lights for example oil tests that indicate a technical manual? a program to download with moving 3D images. A thousand thanks
Hello, if you are asking if our animations are available to acquire... I am sorry they are not... they are used by our instructors for courses in the aircraft. We do provide a manual for our initial classes that have many of the 3D images in them.
I am completely ignorant on this subject, so would one of you experienced pilots help me understand something? It seems that if a helicopter is flying in such a way that any one of the occupants utters an excited "Woo!", that helicopter might be rapidly approaching Servo Transparency, right? Makes sense to me after this very understandable video explained it all. So here's my question: How is the Red Bull acrobatic helicopter configured to prevent this dangerous phenomenon? Does it have special performance-envelope-piercing hydraulics? Something else? Your explanation is most genuinely appreciated!
That is a good question. You would be surprised now mild the maneuvers feel when Arron or Scott perform them. When they place the helicopter is those unusual attitudes it is done with very low Gs. So its not about the helicopter being able to handle those maneuvers, rather the amazing skill of the pilots. Many pilots out there think that yanking and banking a helicopter while putting tremendous stress on the helicopter makes them a great pilot. Its not the attitude of the helicopter that is the skill, its the lack of stress on the airframe while flying the helicopter. I have flown AS350s with Aaron and Scott and they do not maneuver a helicopter like that in everyday flying. If fact the very exact opposite. They are the mildest of pilots, because they are great pilots.
@@EUROSAFETYTRAINING Now that all makes perfect sense, sir! The same thing is true for many F1 racers: they perform what appear to be impossible feats on the track, yet on the street they drive like an Iowa Presbyterian on the way to Church on Sunday. I experienced this firsthand in Canada in 1979 at Jim Russell Racing School at Le Circuit in Mont Tremblant, Quebec, when I spun out on the second day of classes. I entered a turn just a wee bit too early (like a half-foot) near the maximum speed to enter that particular turn and I could feel it in the seat of my pants that the tires were going to break free from the track surface as I tried to turn the wheel a little more to make up for the mistake. The extra G-force I pulled was too much for the coefficient of friction between the rubber and the track, the back end swung around, and spinning off into the grass I went. I had just pierced the performance envelope, and I've remembered that lesson my whole life since. Thanks for the lesson, my friend. This was a great video!
@@leonjourney8334 Of course I'm not a pilot, but it would seem to me that the elements being manipulated BY those hydraulic pumps would have their physical limits, as would anything in the physical world, and that those limits would be why the hydraulics are themselves limited even lower. Again, I ask this out of ignorance rather than any sort of challenge: Are you suggesting that the only thing needed to eliminate servo transparency is a hydraulic system strong enough to **F-O-R-C-E** those rotor blades into submission? I appreciate your help, as I am trying to learn about this phenomenon.
Yes lowering the pitch would reduce load on the rotor blades. Generally though pilots are heading toward the ground when the phenomenon hits so the natural reaction would be to try to increase collective. But since you will never fly in a manner in which you would experience servo transparency its a moot point:)
Choose your role models with discernment, for in seeking to mirror them, you may unwittingly tread a path strewn with unforeseen perils and tribulations.
Non-pilot here...can someone explain why VNE goes DOWN when going up in altitude? I would naturally think it should go up, since the air pressure is lower, and therefore the air is lighter and so takes less work for the engine and rotors to push through/against the air. Or is it because the air is less dense, so the the engine/rotor has to work harder/spin faster to achieve the same amount of lift/speed - so the speed and pitch of the blades needs to be more severe compared to the equivalent speed at lower altitude...and that combo more than offsets the savings from the thinner air being easier to move through?
You almost nailed it with the last half of your post. Vne decreases with altitude because the retreating blade will aerodynamically stall (stop producing lift, not stop spinning) at lower true/indicated airspeeds due to its higher angle of attack to "bite" into that thinner air. Fewer air molecules flowing over the blade surfaces at higher altitudes means more blade pitch is needed to achieve the same effect as at lower altitudes. The blades should not spin faster or slower in normal flight (too fast, you overspeed the rotor system, too slow, the blades fold up and it's over), they change pitch, with appropriate change in power. You should take flight lesson in a helicopter. It will change your life.
@ Makes sense, thank you for taking the time to reply. And yeah I would love to! I’ve decided to pursue my PPL, but leaning toward fixed wing…since I’m also thinking about a career change and flying professionally. I like helicopters more, but the costs are so much higher! It also seems like there’s way fewer opportunities than fixed wing out there, and the pay is worse. Which boggles my mind because it seems like flying rotary wing is much more challenging than fixed wing and so would be paid more. But I guess demand isn’t as high. I’ll probably do a discovery flight anyway just to see how they compare and which I truly prefer.
Once you get into helicopter training and meet people, the opportunities will be revealed. Choose a school wisely...one that sees you as a person, not a source of revenue for the school. You'll know when you walk in, talk to students and instructors, and look at their aircraft. It's an industry built on relationships and reputations. I went straight to rotor-wing and got my helicopter PPL without getting a fixed-wing rating first. Yes, it was expensive. Yes, it was worth it. The cheaper way is to get a fixed-wing PPL and then get a helicopter add-on. Good luck!!!
What's a VNE? How do you put out one of these and not explain it properly, or do it in acronyms so only a pilot would know what you're talking about, which would make this lesson redundant because it's something he or she should already know, no?
could the engineers not Have utilized progressive pressure roll off system? so instead of the controls locking up they limit the hydraulic pressure applied to the rotor system retaining for the most part pilot control??
Im sure they could. I would have to assume its a matter of massive expenditures for an issue that they believe you should never encounter. As an analogy, lets use the Bell 206. If you pull past the TOT red line you will eventually experience severe rotor droop that could cause and accident. You could argue that this is a safety concern in case the pilot would need that power. So Bell should go back and put a much more powerful engine in all old 206s for no cost.
I struggle to believe that this is a design feature. Is it safe to assume that far more squirrel airframes have crashed from jack stalls than would have crashed due to over stressing? I think it is. Sounds like a design flaw to me.
@@EUROSAFETYTRAINING No one made that argument, respectfully, I think you're confused. You've used two examples of dangerous flying and attributed this type of flying to all jack stalls. In reality that's not the case. They can, and have happened during phases of flight that would be considered by most of us as quite normal. But that wasn't my point either. My point was that complex systems should be designed to be as forgiving to human error as possible. This is a design goal of all things technical, not just helicopters. We study human factors because we make mistakes, we're not robots. Manufactures didn't take this into account years ago as much as they do now, but unfortunately many helicopters with these "features" still exist. While training such as yours certainly benefits and contributes to less accidents, a better design would eliminate them.
I do understand what you are saying. My statement was designed to reflect the point in a very blatant manner in order to cut to the chase. An again to be frank, there is no normal phase of flight that can induce servo transparency. One could say that they experienced servo transparency in severe turbulence, but that is a momentary additional force on the rotor system that goes away quickly. An argument could be made in such a instance that you would want the system not to accidentally over stress the rotorhead. By momentarily not applying additional damaging force you are protecting the system. Can you tell me the normal flight you are referring to. The fiberglass rotorhead on the AS350 is an amazing and dependable design, but it has its limits like all mechanical systems. The argument that a hydraulic system that can damage the system be attached to it seems illogical. I'd like to emphasize that the tone perceived in written text may not always align with the intended tone of the author. With this in mind, I genuinely appreciate and enjoy engaging in thoughtful discussions about helicopter flight safety with professionals who are equally committed to achieving operational safety.
@@EUROSAFETYTRAINING I am with the others. It would be great if it would be more forgiving - if it just reduced user input, before design limits are reached, but not turn the heli into undesirable angle would be much safer alternative to warn reckless pilots.
@@EUROSAFETYTRAINING thanks for the reply, and I agree with everything you say. My experience is limited on the 350, but in the 355 a steep turn in a lightly loaded aircraft will set off the limit light. The starflex is a conversation for another day 😂 I guess my overall point is that we often give manufacturers too much slack. We’re having a similar issue with Sikorsky at the moment with their CPI transducers. There is a world wide fault issue with them which causes random fuel changes in the engine. In the worst case scenario it causes a momentary engine roll back and engine out tone. Sikorskys stance on this is “no one has died, it’s fine”, instead of fixing the issue.
I assume you are saying that this was not servo transparency. What do you think the speed was at the time of the pitch up and what was the altitude? There is no doubt that the helicopter is at altitude as evident by the mountainous terrain. There is no doubt that the helicopter was heavy as evident by the passengers seen on the video. There is not doubt that the pilot was giving a "thrill ride" as evident by the exclamations in the cabin. There is no doubt that there was acceleration when descending. There is no doubt that the nose pitched up (first indication of servo transparency). There is no doubt with a descent and then a pitch up that the G forces would increase creating more forces on the servo actuators. There is no doubt that the helicopter rolled to the right (the second indication of servo transparency). Have I said anything that is not correct?
@@EUROSAFETYTRAININGYes, you have said something incorrect. You have used a butt-covering euphemism "servo transparency" when a control systems engineer from any other field would use the term "saturation" or something similar. Frankly, the design of the machine is wanting. Yes, you must stay within the flight envelope of the aircraft, but the aircraft's reaction to approaching those limits should not be "pitch up, roll over and crash." That sort of attitude should have been left behind with the Benson gyrocopter.
Thank you for your attention to detail and for contributing to a rigorous discussion. It’s enlightening to hear the perspective of a seasoned control systems engineer. As for the aircraft design, your frankness is appreciated, and it invites a deeper look into the nuances that distinguish various models and their operational behaviors. Let's continue to dissect these complexities, as each insight brings us closer to the excellence we both seek.
I was looking for this comment. ¨Saturation¨ I understand. Was having a hard time picturing ´transparency´, but if it is what the industry uses more power to them. @@MrSunrise-
LMAO "Servo Control Transparency" :)) Sounds more like a cool feature, you want to have on your machine. "Transparent" = "readable", "easy to perceive or detect" Etc. Only some engineers come, into the computing field, with the idea that "transparency" may define something that is functioning without the user's knowledge. Maybe from here borrowed this confusing term in rotorcraft design. Which is stupid. IMO.
A lot of terminology and names of parts were originally a French word, then directly translated into English. My guess is there is something in the term that was the result of that.
450 psi is piss poor pressure for a Hyd system - Pilots who cowboy and have "Hold my beer" moments shouldn't fly. Limiting maneuvering power is not the answer... Hughes 500 & Bell 407 have done loops and rolls (Hughes has no servos) Even if not certified for such maneuvers the air frames will do them. ( Had a friend loop an OH 6 to beat a Strella ADA missile)
It's not humanly possible to push through 480 pounds with one hand, and if it was the cyclic would break before it would do anything, so it does "lock up". Calling this a safety feature to prevent damage is a little ridiculous as well. High altitudes and aggressive manuvers would cause less dangerous effects than this, like rotor droop, retreating blade stalls, or digging-in in helicopters that dont have this "safety feature" because they have larger hydraulic pumps.
The purpose of these short videos are just that ... short pieces of information. They are not meant as a complete ground school. They are supplemental information. We offer complete ground schools if you wish to get a complete knowledge base of the system.
Thank you for taking the time to view the video in its entirety-your engagement is beneficial to the channel's visibility. I'm intrigued by the rudeness of your critique, and find myself wondering if you are offering substantive feedback or simply are trolling the channel. I would be most appreciative if you could elaborate on your insights, or perhaps you might direct me to a tutorial of your own creation, which I am sure would be enlightening.
"Servo Transparency" I love the name EC gives this to imply some kind of accepted phenomenon. Calll it what it is...a poorly designed, inadequate hydraulic system. This is an example of why you should not fly in a Eurocopter aircraft if you value your life. So you design the hydraulic system to limit the force that can be applied to the swashplate so that the pilot can not damage the aircraft??... even if it means that aircraft crashes into a mountain or the ocean. That's fantastic logic. Even if this was logical n some way, maybe there should be some kind of warning to the pilot that he's approaching a controllability limit before the controls just stop working. One more thing Glen,you say the servo can "push 419 pounds of pressure:. That is an inaccurate statement. The hydraulic actuator can generate a force (in pounds, newtons, etc). It does not push with "pressure". Pressure is force/area. How about putting someone in this video who actually knows what he's talking about...not some ding dong spokesperson with fancy graphics that gives a second rate explanation as to why the AS350 is a dangerous aircraft.
Thank you for taking the time to view the video in its entirety-your engagement is beneficial to the channel's visibility. I see that you took substantial time to compose a rather lengthy response to my video. I can surmise from your response that the video has created a great amount of personal pain on your end. I cannot imagine why a simple educational video could generate such sorrow, but I am truly sorry. As I relayed in the video the helicopter has to be flown in an extreme manner to achieve this phenomenon. If you are a pilot that flys in that manner, yes, without a doubt you should not fly this helicopter. Regarding your comments on 418 lbs. That figure was published in an accident report out of Norway from an accident that occurred there. Between their aviation authorities and test pilots from France, that was the number they published. Please contact the Norwegian authorities on any further needed information on pounds of force. I see that you are proclaiming that you are more intelligent than the engineers that built the AS350, the Norwegian CAA, test pilots at Airbus and myself who you so kindly labeled as ding dong, which I do find hilarious. I welcome your explanation, video, publication of the phenomenon. Bravery appears to flourish behind the veil of anonymity, where one can parade a lion's heart within the safe confines of their digital coliseum.
@@EUROSAFETYTRAINING dont get me wrong, the video is great, but reading your answers to some of these comments is actually even more entertaining than the actual video lol. good for you for staying calm, respectful, and not letting the craziness of the internet get to your nerves ;)
An even longer response but with little substantive content. The only personal pain this issue has caused is for the families of those killed in Airbus helicopters due to subpar designs. You may have read my comment but obviously did not comprehend the issues at hand... "Servo transparency" is a made up term to explain away the lack of an adequate flight control system...answer that. My comment about the 418 pound force was not questioning the value 418...it was pointing out the fact that you don't know the difference between force and pressure... but in an attempt to deflect you point to the genesis of the 418 value. Please put someone in these videos who has some technical background that knows what they are talking about. For those of us who do have an engineering background and know BS when they hear it, your obvious lack of technical competence diminishes your overall credibility and specifically your fabricated explanation of "servo transparency". @@EUROSAFETYTRAINING
Thank you for your comment. It's clear that you have a strong interest in the technical aspects of helicopter operation, and I appreciate the opportunity to clarify any misunderstandings. I understand your concerns regarding the use of 'pounds of force' versus 'pounds of pressure.' In the context of the video, the term was used to communicate concepts in a way that's accessible to a wide range of viewers, some of whom might not have an engineering background. It's a valid technical distinction, and in our effort to make the content broadly understandable, the terminology was simplified. As for 'servo transparency,' this term is recognized within the helicopter industry and is not intended to obscure any shortcomings in design but to describe a specific aerodynamic phenomenon. It's a critical concept for pilots to understand in the interest of safety. All helicopters have limits which we must adhere to, to assume all helicopters should be designed to operate to extreme parameters seems illogical. I am assuming you are comparing the AS350 to some mythical helicopter that is void of any nuances, I am sorry I have never heard of that airframe. Each aviation accident carries with it a profound sense of loss and serves as a critical learning moment for the entire industry. At EUROSAFETY, we are deeply committed to honoring these lessons by delivering exceptional training that prioritizes safety above all else. We strive to ensure our instructional content, offered at no cost, contributes meaningfully to the enhancement of industry-wide safety standards. Should you feel that our resources do not align with your expectations, we acknowledge that there is a wealth of other channels that may meet your specific requirements for technical content. Transparency and credibility are the cornerstones of education, especially in a field where lives depend on the accuracy of the information provided. While I stand behind the content we produce and am open about my credentials and experience, it's challenging to fully address anonymous critiques that don't come with the same level of accountability. I encourage you to reach out with your real name and background so we can have a constructive and open dialogue. After all, it's through professional exchange and peer review that we achieve the highest standards of aviation safety. Thank you again for your engagement and for contributing to a more informed and safety-conscious flying community.
Any other non pilots in here because of that servo helicopter crash video??
Yup haha, really wanted to know what servo transparency meant....
Yup😂
@@SoundShunter72 yep. As a non pilot I Couldn’t sleep until I acquired this useless information. But next time I’m around some heli pilots and they start up on some servo saturation I’m on it.
@@longsleevethong1457 Don't forget to watch a tutorial on autorotation so you're fully prepared.
@@SoundShunter72 I’ve done those. Pretty cool. I’m not a pilot but I fly all the time. I work for rich dudes with all kinds of aircraft. The Texan T6’s and Boeing stearman are my faves. I flew in a lot of blackhawks in the military too.
Great explanation! Thanks for posting!
Glad you enjoyed it!
As a retired 40 year 22,000 hour helicopter pilot I can tell you the key to having a long life …is not flying like a jackass
True
Or fly airplanes :D
@@theHDRflightdeck …… seen more Jackasss fly airplanes and have accidents than helicopters
@@ron6892 no doubt 😁
hello sir happy to hear from you !
A heck of a safety feature. One that that saves the airframe for a few more seconds but causes a crash.
I think you are looking at the issue incorrectly. There is never a situation in which you should be flying in a manner where you could get into servo transparency. Period. The airframe holds you in the air. It holds your life with in. Should a helicopter be able to perform a barrel roll? If the helicopter can not would you consider that helicopter unsafe to fly because you could not perform said barrel roll?
@@EUROSAFETYTRAINING and a need to suddenly avoid a collision such as a possible mid air, and not being able to avoid it cause it might bend the airframe means y’all gonna crash. What a great safety system. (Sarcastic).
@@cfdfirefighterthey surely weighed the trade-offs and determined that this was the safest option. It's probably riskier to allow pilots to override the system, because then they might get too complacent. Either way, rather than making assumptions, it's good to look up this kind of thing to alleviate any sort of concern you might have.
@@R2Bl3nd the F-18 has an override to allow higher than rated G’s on the airframe. Seems like they could include that type of switch, and training on how/when to use it.
@@cfdfirefighter yeah it's certainly worth questioning why; it could absolutely be just a cost-saving measure that's decreasing safety. It could be that they put the upper limit high enough that you wouldn't ever want to push it further; I'm not an expert but I would guess that with helicopters, any amount of bending could potentially lead to a fatal catastrophic failure, just because the power distribution mechanics are so intertwined with the airframe itself, as opposed to being almost entirely self-contained in an engine on a plane.
GM had a problem on the X bodies where the rack and pinion passages would start to plug up and resist flow. With a yank of the steering wheel, system pressure would exceed the pop off of the power steering pump and the steering wheel would lock up. Easing off would restore function, but by then you already ran into a telephone pole.
Thank you for bringing up this interesting case with GM's X bodies. The issue you described with the rack and pinion passages getting clogged, leading to a sudden lock-up of the steering system, is indeed a serious concern. It highlights the importance of maintaining proper flow and pressure in mechanical systems, much like the servo transparency issues we discussed in the video. Of course the difference is that the GM issue was a failure within the system and servo transparency is reaching the maximum force of what the servos can apply.
In the case of GM’s X bodies, the sudden increase in system pressure overriding the power steering pump's pop-off valve demonstrates a critical design consideration. It's a stark reminder of how mechanical failures can have immediate and dangerous consequences, as you mentioned with the steering wheel locking up unexpectedly. Within servo transparency the lock up is achieved through a purposeful application of force on the rotor system.
Thanks for sharing this example, as it adds a practical dimension to our discussion about the complexities and challenges in mechanical and hydraulic systems.
I absolutely loved flying 🪽 the AS 350 B2 👍 🇺🇸 Never experienced this. I have accumulated more than 25000 hours in helicopters 🚁 and all I can say is; every single one of the types I've flown has limits. Just like all machines. Know the limits, including your own.
Well said
words to live by!! how about flying high and in hi winds?
Hey Glen,
maybe you can give some insight about the dual hydraulics + increased internal take off weight on the AS350. Is it correct that one theoretically would get into servo transparency earlier in a helicopter with dual hydraulics(35bars) vs. single hydraulics (40bars) and even earlier in a dual hydraulics while using the increased internal take off weight? Is this the reason why there is a Limit light on the dual hydraulic system and not on the single system?
Thanks in advance!
I think it would be best to lower the green area on the airspeed Indicator to 120 max then from that to 150 a yellow color to remind pilots of the situation.
Excelente vídeo. Estou aprendendo muito sobre essa máquina magnífica que é o AS350. Forte abraço do Brasil.
Thank you!
Mentioning "canyon walls" reminded me of Sundance accident (NTSB Accident Number: LAX03MA292; AS350BA, N270SH). A pilot of Grand Canyon tour helicopter, used to perform thrill rides, including flying at Vne and extreme pitch and roll angles. Servo transparency was considered and discussed in the report, but finally it was ruled out. I'm not going into details, but it shows, that you have to work for the transparency to manifest itself, usually by breaching several limits at once.
Another thing is, people seem not to be bothered about the possibility of mast bumping in a Bell or Robinson (there is at least one video on YT, that shows it almost happening) or Kamov's rotors intersecting each other, when flying slightly above Vne. These are not flaws, but part of the design as even the best ones have their limits. One can damage or even break a jetfighter or aerobatic plane, with a gross misuse of controls.
Well said!
"servo transparency" - what a lovely euphemism. How about "servo saturation", or perhaps "servo inadequacy". If it was really a question of preventing damage to the aircraft, there would be an indication of approaching saturation - either audible or visual.
If you fly the helicopter within responsible parameters you will never encounter this phenomenon.
@@EUROSAFETYTRAINING Maybe true, but manufacturers have a moral obligation to make their aircraft as forgiving as reasonably possible. I've had jack stall demonstrated to me a few times (I don't have a lot of squirrel time) and while it was definitely an abnormal flight maneuver, i wouldn't say that it's outside of the realm of possibility in some conditions. It's easy to pass the blame onto the pilot, but if there's one thing we know for certain, humans make mistakes. A slightly higher tolerance could save lives.
To put is very simply, there is absolutely no reason to fly a helicopter in a manner in which you can experience servo transparency. It would be akin to saying that the 737 has a deign flaw because you cant do a barrel roll in it.
@@EUROSAFETYTRAINING a fairly basic steep turn will set the limit light off in an as355, are steep turns barrel rolls ? Your argument is similar to Robinson’s argument against mast bumping, and it’s a bit of a cop out. At the end of the day human error is guaranteed, and the best human interface designs (for anything technical, not just helicopters) will be forgiving to that error. Good training will reduce the error, a better design will eliminate it, which will save more lives ?
Thank you for your insightful comments about the technical aspects of helicopter operations, specifically in reference to the incident with the 355 model in St. Petersburg. While the maneuver might seem normal, a closer examination of the pitch and roll parameters reveals they are quite extreme, something I'm sure you'd agree is not advisable for safe flying.
I concur with your point on human error. However, flying a helicopter recklessly is a deliberate choice, not just an error, and is undeniably dangerous.
Regarding the technical specifics, the hydraulic pump on this model can indeed handle pressures over 1300 psi, though it's regulated to 580 psi to avoid damaging the rotor system during flight. I believe the discussion should focus on whether a complete redesign of the rotorhead is more beneficial than merely adjusting the hydraulic pressure.
I hope my response doesn't come off as dismissive or similar to Robinson's style. My aim is to engage in a constructive and technical discussion about helicopter safety. Looking forward to more such engaging exchanges!
It would be interesting to know what the difference is between the maximum force that the servo allows to be exerted on the aircraft and the force that the engineers designed the aircraft to be able to withstand.
The concern is the long term health of the composite rotor system. There is not a helicopter made where the manufacture publishes the breaking point force of their rotor system.
@EUROiSAFETY do you think it would be feasible to design the aircraft in a way whereby when the pilot reaches the point of servo transparency happening, instead of completely preventing further input to the controls it will instead sound an alarm and stiffen up the controls significantly so it requires effort to move them beyond that point but it allows it to happen if the pilot really forces it? It seems that when this happens the aircraft is going to crash anyway, so might as well give the pilot a chance of recovery. Then once the aircraft has been pushed beyond the limit it must have the parts replaced that endured the extra stresses before its next flight.
Let make this discussion simple. The RFM states... In the limitation section....The following are forbidden: - Aerobatic maneuvers.
The Federal Code of Regulations state.... § 91.9 Civil aircraft flight manual, marking, and placard requirements.
(a) Except as provided in paragraph (d) of this section, no person may operate a civil aircraft without complying with the operating limitations specified in the approved Airplane or Rotorcraft Flight Manual, markings, and placards, or as otherwise prescribed by the certificating authority of the country of registry.
You should never be flying this helicopter in a manner where you will ever experience servo transparency. Period.
@EUROiSAFETY oh I absolutely agree. I think perhaps there was some misunderstanding in what I was saying, because I was not for one minute implying that people should fly in a reckless manor. But nevertheless it is evident that sometimes some people do push it too far, whether on purpose or not. Even the guy who flew the prototype of the 747 barrel rolled it twice in front of everyone. It doesn't mean they deserve to die by default though, along with all their innocent passengers, when they could potentially have been saved if only the servo allowed them a little more power at a critical moment though does it?
I apologize if I seem blunt or dismissive. My frustration likely stems from the difficulty in conveying what seems to me a straightforward concept. Many have commented on the video, suggesting that the hydraulic pressure in the AS350 should be increased. However, this overlooks the purpose and potential consequences of such a change. For instance, while it's true that the pump can generate over 1300 psi at 390 NR, increasing the system's pressure isn't a simple task. Doing so would require the helicopter to undergo complete recertification because this change could affect all components.
Moreover, past engineering analyses have shown that increased forces in the hydraulic system could strain the rotorhead. This implies that a complete redesign of the rotor system might be necessary. Consider the expenses involved in just these two adjustments. The costs would likely run into millions of dollars, driving up the helicopter's price substantially. Consequently, the helicopter could become too expensive for its target market, leading to a decline in sales. Such a significant investment and potential loss of business, just to accommodate the demands of a few who wish to operate the helicopter in an inadvisable way, does not seem like a sound business decision.
The addition of dual hydraulics to the helicopter led to a noticeable decrease in complaints about servo transparency. This change, however, was misunderstood by many. Contrary to popular belief, the introduction of dual hydraulics did not increase the system's pressure. It seems that the mere thought that the pressure had been increased was enough to silence the complaints. This suggests that the issue may be more about perception than actual mechanical shortcomings. If people believed that the problem was resolved with the new system, even when the pressure remained the same, it indicates that the original concerns might have been more psychological than technical.
If the system were to operate under higher pressure, the manufacturer would bear the responsibility for any resultant damage to the airframe. In a legal scenario, the argument might be that if the pressure is available, pilots should be permitted to utilize it. This places Airbus in a precarious, no-win situation.
Additionally, there seems to be a widespread misconception among pilots regarding the likelihood of encountering servo transparency. Except in cases of exceeding VNE, it's highly unlikely that many pilots have ever experienced it. Even among your acquaintances, it's improbable that anyone has felt it. On the off chance someone has, it's likely that they're known for unconventional or erratic flying styles. The hydraulic pressure in the AS350 is more than sufficient for even the most intense flight maneuvers.
In every instance where servo transparency contributed to a crash, the pilot's conduct was extremely reckless. It is not, in my opinion, Airbus' responsibility to cater to the whims of such pilots. If I ever believed there was a genuine issue with the system, I would be the first to voice my concerns loudly. My previous videos have been candid about various helicopter components when problems arose, proving my impartiality. However, I firmly believe that the hydraulic pressure in the AS350 is not a concern for professional pilots who operate the aircraft responsibly.
Hi, congratulations for all your descriptions, which are truly fantastic, I wanted to ask you, is there any school program or software that indicates all the faults, lights for example oil tests that indicate a technical manual? a program to download with moving 3D images. A thousand thanks
Hello, if you are asking if our animations are available to acquire... I am sorry they are not... they are used by our instructors for courses in the aircraft. We do provide a manual for our initial classes that have many of the 3D images in them.
I am completely ignorant on this subject, so would one of you experienced pilots help me understand something?
It seems that if a helicopter is flying in such a way that any one of the occupants utters an excited "Woo!", that helicopter might be rapidly approaching Servo Transparency, right? Makes sense to me after this very understandable video explained it all.
So here's my question: How is the Red Bull acrobatic helicopter configured to prevent this dangerous phenomenon? Does it have special performance-envelope-piercing hydraulics? Something else?
Your explanation is most genuinely appreciated!
That is a good question. You would be surprised now mild the maneuvers feel when Arron or Scott perform them. When they place the helicopter is those unusual attitudes it is done with very low Gs. So its not about the helicopter being able to handle those maneuvers, rather the amazing skill of the pilots. Many pilots out there think that yanking and banking a helicopter while putting tremendous stress on the helicopter makes them a great pilot. Its not the attitude of the helicopter that is the skill, its the lack of stress on the airframe while flying the helicopter. I have flown AS350s with Aaron and Scott and they do not maneuver a helicopter like that in everyday flying. If fact the very exact opposite. They are the mildest of pilots, because they are great pilots.
@@EUROSAFETYTRAINING Now that all makes perfect sense, sir! The same thing is true for many F1 racers: they perform what appear to be impossible feats on the track, yet on the street they drive like an Iowa Presbyterian on the way to Church on Sunday.
I experienced this firsthand in Canada in 1979 at Jim Russell Racing School at Le Circuit in Mont Tremblant, Quebec, when I spun out on the second day of classes.
I entered a turn just a wee bit too early (like a half-foot) near the maximum speed to enter that particular turn and I could feel it in the seat of my pants that the tires were going to break free from the track surface as I tried to turn the wheel a little more to make up for the mistake. The extra G-force I pulled was too much for the coefficient of friction between the rubber and the track, the back end swung around, and spinning off into the grass I went.
I had just pierced the performance envelope, and I've remembered that lesson my whole life since.
Thanks for the lesson, my friend. This was a great video!
F1 is a great analogy! A lot of similarities with race cars.
A lot of helicopters do have real hydraulic pumps that don't have this limitation or "safety feature" as this guy makes it out to be.
@@leonjourney8334 Of course I'm not a pilot, but it would seem to me that the elements being manipulated BY those hydraulic pumps would have their physical limits, as would anything in the physical world, and that those limits would be why the hydraulics are themselves limited even lower.
Again, I ask this out of ignorance rather than any sort of challenge: Are you suggesting that the only thing needed to eliminate servo transparency is a hydraulic system strong enough to **F-O-R-C-E** those rotor blades into submission?
I appreciate your help, as I am trying to learn about this phenomenon.
Hi Glenn, so if you do find yourself in this situation the correct action is to lower the collective?
Yes lowering the pitch would reduce load on the rotor blades. Generally though pilots are heading toward the ground when the phenomenon hits so the natural reaction would be to try to increase collective. But since you will never fly in a manner in which you would experience servo transparency its a moot point:)
cool! great explanation. thanks :)
Glad you enjoyed it!
How about Fred North’s videos? He manuevers his a star beautifully, does he ever get transparency?
Choose your role models with discernment, for in seeking to mirror them, you may unwittingly tread a path strewn with unforeseen perils and tribulations.
Non-pilot here...can someone explain why VNE goes DOWN when going up in altitude? I would naturally think it should go up, since the air pressure is lower, and therefore the air is lighter and so takes less work for the engine and rotors to push through/against the air. Or is it because the air is less dense, so the the engine/rotor has to work harder/spin faster to achieve the same amount of lift/speed - so the speed and pitch of the blades needs to be more severe compared to the equivalent speed at lower altitude...and that combo more than offsets the savings from the thinner air being easier to move through?
You almost nailed it with the last half of your post. Vne decreases with altitude because the retreating blade will aerodynamically stall (stop producing lift, not stop spinning) at lower true/indicated airspeeds due to its higher angle of attack to "bite" into that thinner air. Fewer air molecules flowing over the blade surfaces at higher altitudes means more blade pitch is needed to achieve the same effect as at lower altitudes. The blades should not spin faster or slower in normal flight (too fast, you overspeed the rotor system, too slow, the blades fold up and it's over), they change pitch, with appropriate change in power. You should take flight lesson in a helicopter. It will change your life.
@ Makes sense, thank you for taking the time to reply. And yeah I would love to! I’ve decided to pursue my PPL, but leaning toward fixed wing…since I’m also thinking about a career change and flying professionally. I like helicopters more, but the costs are so much higher! It also seems like there’s way fewer opportunities than fixed wing out there, and the pay is worse. Which boggles my mind because it seems like flying rotary wing is much more challenging than fixed wing and so would be paid more. But I guess demand isn’t as high. I’ll probably do a discovery flight anyway just to see how they compare and which I truly prefer.
Once you get into helicopter training and meet people, the opportunities will be revealed. Choose a school wisely...one that sees you as a person, not a source of revenue for the school. You'll know when you walk in, talk to students and instructors, and look at their aircraft. It's an industry built on relationships and reputations. I went straight to rotor-wing and got my helicopter PPL without getting a fixed-wing rating first. Yes, it was expensive. Yes, it was worth it. The cheaper way is to get a fixed-wing PPL and then get a helicopter add-on. Good luck!!!
What's a VNE? How do you put out one of these and not explain it properly, or do it in acronyms so only a pilot would know what you're talking about, which would make this lesson redundant because it's something he or she should already know, no?
Never exceed speed
@@EUROSAFETYTRAINING Thank you.
could the engineers not Have utilized progressive pressure roll off system? so instead of the controls locking up they limit the hydraulic pressure applied to the rotor system retaining for the most part pilot control??
Im sure they could. I would have to assume its a matter of massive expenditures for an issue that they believe you should never encounter. As an analogy, lets use the Bell 206. If you pull past the TOT red line you will eventually experience severe rotor droop that could cause and accident. You could argue that this is a safety concern in case the pilot would need that power. So Bell should go back and put a much more powerful engine in all old 206s for no cost.
I struggle to believe that this is a design feature. Is it safe to assume that far more squirrel airframes have crashed from jack stalls than would have crashed due to over stressing? I think it is. Sounds like a design flaw to me.
I respectfully disagree. An argument that an aircraft should be designed to be flown extremely dangerously seems illogical.
@@EUROSAFETYTRAINING No one made that argument, respectfully, I think you're confused. You've used two examples of dangerous flying and attributed this type of flying to all jack stalls. In reality that's not the case. They can, and have happened during phases of flight that would be considered by most of us as quite normal. But that wasn't my point either.
My point was that complex systems should be designed to be as forgiving to human error as possible. This is a design goal of all things technical, not just helicopters. We study human factors because we make mistakes, we're not robots. Manufactures didn't take this into account years ago as much as they do now, but unfortunately many helicopters with these "features" still exist. While training such as yours certainly benefits and contributes to less accidents, a better design would eliminate them.
I do understand what you are saying. My statement was designed to reflect the point in a very blatant manner in order to cut to the chase. An again to be frank, there is no normal phase of flight that can induce servo transparency. One could say that they experienced servo transparency in severe turbulence, but that is a momentary additional force on the rotor system that goes away quickly. An argument could be made in such a instance that you would want the system not to accidentally over stress the rotorhead. By momentarily not applying additional damaging force you are protecting the system. Can you tell me the normal flight you are referring to. The fiberglass rotorhead on the AS350 is an amazing and dependable design, but it has its limits like all mechanical systems. The argument that a hydraulic system that can damage the system be attached to it seems illogical.
I'd like to emphasize that the tone perceived in written text may not always align with the intended tone of the author. With this in mind, I genuinely appreciate and enjoy engaging in thoughtful discussions about helicopter flight safety with professionals who are equally committed to achieving operational safety.
@@EUROSAFETYTRAINING I am with the others. It would be great if it would be more forgiving - if it just reduced user input, before design limits are reached, but not turn the heli into undesirable angle would be much safer alternative to warn reckless pilots.
@@EUROSAFETYTRAINING thanks for the reply, and I agree with everything you say.
My experience is limited on the 350, but in the 355 a steep turn in a lightly loaded aircraft will set off the limit light. The starflex is a conversation for another day 😂
I guess my overall point is that we often give manufacturers too much slack. We’re having a similar issue with Sikorsky at the moment with their CPI transducers. There is a world wide fault issue with them which causes random fuel changes in the engine. In the worst case scenario it causes a momentary engine roll back and engine out tone. Sikorskys stance on this is “no one has died, it’s fine”, instead of fixing the issue.
So its like jacking up your truck with a little one ton jack and your jack goes "sqeeee" instead of lifting the truck.
Am an Ec 130 t2 pilot
Very cool! Who do you fly for?
2:30 This crash occurred when the pilot was flying 12Knots below the VNE for his altitude.
I assume you are saying that this was not servo transparency. What do you think the speed was at the time of the pitch up and what was the altitude? There is no doubt that the helicopter is at altitude as evident by the mountainous terrain. There is no doubt that the helicopter was heavy as evident by the passengers seen on the video. There is not doubt that the pilot was giving a "thrill ride" as evident by the exclamations in the cabin. There is no doubt that there was acceleration when descending. There is no doubt that the nose pitched up (first indication of servo transparency). There is no doubt with a descent and then a pitch up that the G forces would increase creating more forces on the servo actuators. There is no doubt that the helicopter rolled to the right (the second indication of servo transparency). Have I said anything that is not correct?
@@EUROSAFETYTRAININGYes, you have said something incorrect. You have used a butt-covering euphemism "servo transparency" when a control systems engineer from any other field would use the term "saturation" or something similar. Frankly, the design of the machine is wanting. Yes, you must stay within the flight envelope of the aircraft, but the aircraft's reaction to approaching those limits should not be "pitch up, roll over and crash." That sort of attitude should have been left behind with the Benson gyrocopter.
Thank you for your attention to detail and for contributing to a rigorous discussion. It’s enlightening to hear the perspective of a seasoned control systems engineer. As for the aircraft design, your frankness is appreciated, and it invites a deeper look into the nuances that distinguish various models and their operational behaviors. Let's continue to dissect these complexities, as each insight brings us closer to the excellence we both seek.
I was looking for this comment. ¨Saturation¨ I understand. Was having a hard time picturing ´transparency´, but if it is what the industry uses more power to them. @@MrSunrise-
All businesses stay away from terms that would be less than complementary to their product.
I could totally push with 418 lb of force.
ok so in simple terms, fly the aircraft safely and you will be fine haha
LMAO "Servo Control Transparency" :)) Sounds more like a cool feature, you want to have on your machine. "Transparent" = "readable", "easy to perceive or detect" Etc. Only some engineers come, into the computing field, with the idea that "transparency" may define something that is functioning without the user's knowledge. Maybe from here borrowed this confusing term in rotorcraft design. Which is stupid. IMO.
A lot of terminology and names of parts were originally a French word, then directly translated into English. My guess is there is something in the term that was the result of that.
450 psi is piss poor pressure for a Hyd system - Pilots who cowboy and have "Hold my beer" moments shouldn't fly.
Limiting maneuvering power is not the answer... Hughes 500 & Bell 407 have done loops and rolls (Hughes has no servos)
Even if not certified for such maneuvers the air frames will do them. ( Had a friend loop an OH 6 to beat a Strella ADA missile)
It's not humanly possible to push through 480 pounds with one hand, and if it was the cyclic would break before it would do anything, so it does "lock up". Calling this a safety feature to prevent damage is a little ridiculous as well. High altitudes and aggressive manuvers would cause less dangerous effects than this, like rotor droop, retreating blade stalls, or digging-in in helicopters that dont have this "safety feature" because they have larger hydraulic pumps.
The pump produces over 1300 psi at 390 NR. The system is regulated to 580 psi. So its not a pump issue.
Bumma
Your videos is too short
The purpose of these short videos are just that ... short pieces of information. They are not meant as a complete ground school. They are supplemental information. We offer complete ground schools if you wish to get a complete knowledge base of the system.
Fairly poor explanation of what really happens but will serve the purpose to make people avoid the issue.
Thank you for taking the time to view the video in its entirety-your engagement is beneficial to the channel's visibility. I'm intrigued by the rudeness of your critique, and find myself wondering if you are offering substantive feedback or simply are trolling the channel. I would be most appreciative if you could elaborate on your insights, or perhaps you might direct me to a tutorial of your own creation, which I am sure would be enlightening.
That comment @RVDT2 is Spoken like a true Robinson Driver 🤷🏼♂️
"Servo Transparency" I love the name EC gives this to imply some kind of accepted phenomenon. Calll it what it is...a poorly designed, inadequate hydraulic system. This is an example of why you should not fly in a Eurocopter aircraft if you value your life. So you design the hydraulic system to limit the force that can be applied to the swashplate so that the pilot can not damage the aircraft??... even if it means that aircraft crashes into a mountain or the ocean. That's fantastic logic. Even if this was logical n some way, maybe there should be some kind of warning to the pilot that he's approaching a controllability limit before the controls just stop working.
One more thing Glen,you say the servo can "push 419 pounds of pressure:. That is an inaccurate statement. The hydraulic actuator can generate a force (in pounds, newtons, etc). It does not push with "pressure". Pressure is force/area. How about putting someone in this video who actually knows what he's talking about...not some ding dong spokesperson with fancy graphics that gives a second rate explanation as to why the AS350 is a dangerous aircraft.
Thank you for taking the time to view the video in its entirety-your engagement is beneficial to the channel's visibility. I see that you took substantial time to compose a rather lengthy response to my video. I can surmise from your response that the video has created a great amount of personal pain on your end. I cannot imagine why a simple educational video could generate such sorrow, but I am truly sorry. As I relayed in the video the helicopter has to be flown in an extreme manner to achieve this phenomenon. If you are a pilot that flys in that manner, yes, without a doubt you should not fly this helicopter. Regarding your comments on 418 lbs. That figure was published in an accident report out of Norway from an accident that occurred there. Between their aviation authorities and test pilots from France, that was the number they published. Please contact the Norwegian authorities on any further needed information on pounds of force. I see that you are proclaiming that you are more intelligent than the engineers that built the AS350, the Norwegian CAA, test pilots at Airbus and myself who you so kindly labeled as ding dong, which I do find hilarious. I welcome your explanation, video, publication of the phenomenon. Bravery appears to flourish behind the veil of anonymity, where one can parade a lion's heart within the safe confines of their digital coliseum.
@@EUROSAFETYTRAINING dont get me wrong, the video is great, but reading your answers to some of these comments is actually even more entertaining than the actual video lol. good for you for staying calm, respectful, and not letting the craziness of the internet get to your nerves ;)
An even longer response but with little substantive content. The only personal pain this issue has caused is for the families of those killed in Airbus helicopters due to subpar designs. You may have read my comment but obviously did not comprehend the issues at hand...
"Servo transparency" is a made up term to explain away the lack of an adequate flight control system...answer that.
My comment about the 418 pound force was not questioning the value 418...it was pointing out the fact that you don't know the difference between force and pressure... but in an attempt to deflect you point to the genesis of the 418 value. Please put someone in these videos who has some technical background that knows what they are talking about. For those of us who do have an engineering background and know BS when they hear it, your obvious lack of technical competence diminishes your overall credibility and specifically your fabricated explanation of "servo transparency". @@EUROSAFETYTRAINING
Thank you for your comment. It's clear that you have a strong interest in the technical aspects of helicopter operation, and I appreciate the opportunity to clarify any misunderstandings.
I understand your concerns regarding the use of 'pounds of force' versus 'pounds of pressure.' In the context of the video, the term was used to communicate concepts in a way that's accessible to a wide range of viewers, some of whom might not have an engineering background. It's a valid technical distinction, and in our effort to make the content broadly understandable, the terminology was simplified.
As for 'servo transparency,' this term is recognized within the helicopter industry and is not intended to obscure any shortcomings in design but to describe a specific aerodynamic phenomenon. It's a critical concept for pilots to understand in the interest of safety. All helicopters have limits which we must adhere to, to assume all helicopters should be designed to operate to extreme parameters seems illogical. I am assuming you are comparing the AS350 to some mythical helicopter that is void of any nuances, I am sorry I have never heard of that airframe.
Each aviation accident carries with it a profound sense of loss and serves as a critical learning moment for the entire industry. At EUROSAFETY, we are deeply committed to honoring these lessons by delivering exceptional training that prioritizes safety above all else. We strive to ensure our instructional content, offered at no cost, contributes meaningfully to the enhancement of industry-wide safety standards. Should you feel that our resources do not align with your expectations, we acknowledge that there is a wealth of other channels that may meet your specific requirements for technical content.
Transparency and credibility are the cornerstones of education, especially in a field where lives depend on the accuracy of the information provided. While I stand behind the content we produce and am open about my credentials and experience, it's challenging to fully address anonymous critiques that don't come with the same level of accountability. I encourage you to reach out with your real name and background so we can have a constructive and open dialogue. After all, it's through professional exchange and peer review that we achieve the highest standards of aviation safety.
Thank you again for your engagement and for contributing to a more informed and safety-conscious flying community.
Is this the only helicopter that experiences "servo transparency"?