Aircraft Engine Vibration Detection System
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- Опубліковано 7 лют 2025
- Welcome letters and gentlemen, and this is a basic understanding of jet engine vibration and systems.  obviously I cannot go into further detail because it would take me at least a day and a half of talking just to explain the minute details, but this is a general perspective of what we encounter as maintenance personnel.
We take engine vibration very seriously and we follow maintenance manual procedures, to prevent any kind of damage and deterioration to the engine to ensure the safety of your flight. Pilots also take part in this because they are the ones that are relaying some of this information to us but we are the ones responsible for troubleshooting the primary issues and the causes of the issues.
I hope you guys all enjoyed this video. Please feel free to leave your comments and concerns down in the comments, thank you very much to all for supporting and watching. I appreciate you all.
Cheers, yours truly Stig 🤙
#stigaviation #themoreyouknow #aviation #boeing #aircraftmaintenance #aircraftmechanic #aviationnation #learningeveryday #wefixyoufly #aircraft #jetengine #vibration #blades 
Once again you nailed a complex subject with the right amount of depth, in other words everyone can appreciate your production. Very good work!
Much appreciated! Thank you so much. I hope it wasn’t too confusing. I know I tend to talk a lot and repeat myself in my videos 😅
This is quickly becoming my favorite UA-cam channel.
Thank you very much Nolan. It’s a pleasure having you here.
Thank you so much for teaching complex matters in simple terms. Albert Einstein said that only very bright people have the capacity to explain difficult issues in easy to understand ways. Much respect
Glad it was helpful! And thank you for the kind words. Much appreciated Carlos 👍
@Stig- the statement about always learning something in aviation holds true 2:26. I have worked on highly experimental turbofans/turbo jets in both assembly and test environments, Even working with forced imbalance like 3x for ETOPS Cert, had no idea what ips actually meant. Balance is black magic voodoo stuff, i give our guys so much respect. Love from a P&W A&P avgeek @ Stig Aviation.
You are so right my friend. It’s a never ending learning process with aviation. The more I dig into systems and subsystems I discover more information. This video was very hard to make because of so much information, and that’s just scratching the surface. I happened to start digging into the wiring schematics.. and boy I tell you.. I was lost in there for about 3 hours 😅.
Thank you Stig, great to see the work that’s done to keep engines safe, longer video much appreciated - it’s a big subject!
Glad you enjoyed it and indeed a very big subject… there’s more information to this, this video was a simplified version of how it works.
Another awesome video! Always look forward to your videos and I always learn something new. Keep them coming! Cheers!!
Thank you! Cheers! 🤙
As usual.. a very informative and interesting video. Thanks Stig.
My pleasure!
seeing the graph (at 2:26) reminds me of an engine N2 VIB went up over 8.0 and we couldn't even stand up without hold onto something for balance in the flight deck...
8.0 😳😳😳😳. Good lord. You’re lucky the engine didn’t grande on you.
Great video! As a line mechanic in the ‘80s I used to enjoy doing a three shot plot to balance the fan of RB211-22B and CF6-50C2 engines. We would taxi to the blast fence and do three high powered run ups with trial weights placed 120-degrees apart for each run up. Using the onboard vibration monitoring sensors we would record the vibration amplitude on a matrix graph after each run up. Where the arcs intersected would give us the position and weight of the required balance weight. It never failed to be perfect. Airline line maintenance can be interesting and fun.
Those high-power runs always are a joy, and bring the engine up to 80 to 90% power, brake set, and the wings flopping around, airplane wanted to go. Funny, you mentioned those engines I just did a video on differentiating engine, spool technology, I think you’d enjoy it.
Just love the way you explain these stuff
Great job
Glad you like them! I appreciate you watching 👍
This man Truely is the stig of aviation.
Also what’s crazy is only 3 bolts hold the engine onto the plane for high bypass engines
Stig, Please do explain how the attaching pins are designed to shear off and release the engine in flight, to protect the wing if the vibration exceeds safe limits. Really do appreciate these fantastic educational videos.
A bit more than 3. Usually massive engines like that have 8-9 massive bolts. Usually 5 in front mount plate and 4 in the back. Older smaller engines such as the JT8D had 3 bolts.
That’s a complex question.. I’ll have to work on that one. But in quick terms the sheer points are usually at the pylon/engine connection point. If over stressed the engine is usually designed to snap off either Up and over the wing or Down and away to prevent it from hitting the horizontal stabilizer and flaps.
Yes that is crazy... If I'm not mistaken, the 737 CFM's (& the old JT8D's) have 3 mount "cone" bolts that are designed to break way in extreme vibration situations (not to mention the mount bolts for the thrust link, more for dynamic loading). The A320 CFM's (and the other options, V2500's LEAP's, & PW GTF's) actually have 8 smaller mount bolts that attach the engine to the pylon (4 on the fwd mount & 4 on the aft mount)... but still, designed to break way in extreme vibration situations...
@@Flyby-1000 yup 👍 exactly. Absolutely correct ✅
Love the technical details that are brought to light in these videos! Thanks!
It’s my pleasure. Thank you for being here and enjoying it 👍
Another Stig educational video.
Thank you 🙏
I am so infatuated with jet engines. They are the most fascinating achievement of humanity imo.
Luckily I grew up in a small town with an international airport. The fascination has been there since early childhood.
I’m right there with you, I think these machines are the most incredible thing that have been designed. Absolutely phenomenal
Bruh. How it’s made soundtrack 😂. Great content once again!
Thank you. I appreciate you watching John.
Great video stig! As always you explain things very well I've worked in an engine shop for over 5 years and High vibration is one thing we fear at test after repair/overhaul , one time it was because the grind procedure was done incorrectly and the clearance between a stator abradable coating and a 4th stage HPC rotor was too high maybe a couple thousands over and that was the issue all along! 😅
It’s amazing how precise these engines have to be built. Very little room for error. Even something that small can cause incredible damage. I’m glad for diligent people like you that work hard to resolve the problems before we hang these engines on the wings. 👍
Hey. Just wanted to say I absolutely love your videos, and the detail with which you explain everything. Always look forward to your next upload. Couple of questions, if you don't mind: Can you please do a video about the pressurisation systems? Also, it seems you really love your job. What kind of day is a 'bad day' for Stigaviation?
I appreciate that! And I’ll get you something on pressurization soon. 👍. As for a bad day for me… 🤔… well I suppose grounding an aircraft because of something I find that I deem not airworthy. I don’t enjoy causing delays for my flying public, but safety comes first.
Wow. This 8 minute video felt like 30 seconds. Keep up the good work!
Thank you Steve. If you enjoyed this check out the other videos that are much longer, if that’s your preference. But overall thanks for being here
thanks for these videos! absolutely fascinating stuff :) keep them coming.
Glad you enjoyed it 👍
Amazing
Thank you! Cheers!
Good good stig keep it up😊😊
Thanks 😊
woah the first clip looks so cool
Yup. That was a high power run. Fun stuff 👍
Thank you for sharing this video and information.
My pleasure. Thank you for watching
These videos are really informative. It’s nice to know what’s going on under the cowling.
Glad you enjoyed it
Thank you.
Awesome vlog.
Glad you enjoyed it sir. Thank you.
Excellent explanation Stig 🤙!!
Glad you liked it!
To me, the most noticeable vibration of airliners would be the one when any aircraft takes off and climbs; there will always be a sudden whole fuselage vibration, from nose to tail, just like a cat does, which is probably due to the natural frequency matching between the fuselage and engine vibration. I've always anticipated that whenever I take an airplane and I love it.
It’s definitely an interesting sensation, at the same time exhilarating. 👍
like a vibrator
Wow i did not know they used Piezzo technology on the vibration sensors. I always learn something new from your videos. Thanks alot.
You bet! Glad you enjoyed it 👍
Amazing work as always. This is valuable stuff.
Glad you enjoyed it
Crouching underneath that engine really puts it into perspective just how enormous they are on the bigger birds
Absolutely massive
4:18 I found a CFM-56 fan blade on a A340 with almost the exact same tip damage, I was stunned when it was within MM limits and had been flying like that for months. 🇦🇺
It’s interesting how the parameters get more scrutinized when the damage starts going towards the root of the blade.
Thanks Stig, for the deatiled info, How oiften are the T/C berings changed in a TF engine
That one is subjective… only when the engine begins to show degradation, vibration and high oil consumption is when that will happen. Basically the engine is not performing as expected then those components will be looked at and changed as required per manufacturer specifications
Great video as always! On this Airbus there is a message "Fuel auto transfer fault" and something about central tank but there is reflection and I can not see clearly 13560lbs of fuel is not enough to "reach" central tank. Do you remember what was wrong?
If I remember correctly it was a fuel imbalance issue. I’ll have to check my records again. It was a while back.
I thought that in A320sh to address fuel imbalance is to shut the pump on the lower tank and feed both engines from the tank that is higher until is equal. Correct me if I am wrong. Thanks @@StigAviation
@@voytekcyvr1936 you also have to open the transfer valve from downstairs at the fuel panel. It’s a bit of a convoluted process with airbus.
Subbed
Thank you. I appreciate you being here 👍
Thanks, Nice again!.......
My pleasure 👍
I love that you showed the same engine I have 😂 GM 6.0 liter vortec v8
😅
You should also talk about the engine spinners..why they are shaped that way and the change made from the past,,, because they flamed out in heavy rain😮
Well, the spinner is shaped in a particular way to optimize airflow into the core and also to break up ice formation. Is that what you’re talking about?
@@StigAviationactually talking about the change in shape from "Madonna" to "dolly parton's.😅
🤣🤣🤣. The pointy cones. Well that’s manufacturing preference. RR Always does the pointy cones. GE CFM PW do the more “rounded” ones. Hence why you see the Rolls Royce have the rubber tip.
@@StigAviation just a little background..I learned a lot, experienced a lot. Flew and built a lot. Now all that knowledge and experience wasted. Retired. When I was a kid I'd see airplanes flying overhead and wishing I was up there. Now I am on the ground and glad I'm NOT up there. Especially when the weather is bad... haha 😂. Today,,my safety wire plyers Are older than most "technicians". No longer mechanics
Thanks for a great video. At what point in the maintenance lifecycles are xray/deeper imaging checks of blades are done? Is it only during overhaul s? Keep the great content coming ❤
The engine blade inspection is done periodically and scheduled. Also if there was damage it will be done. It’s usually an Eddie current test or ultrasonic test. As for the xray inspection … well that’s a whole different animal. That’s a very serious and very dangerous test. It’s done on very very heavy checks on usually old aircraft. Also done if structural damage is suspected.
I don't know if it counts but. I used to be on the old 777 often. And everytime the engines start. I could always feel the plane started vibrating as the engines started up. I think it was usually the Trent 800 or the PW. There was absolutely no vibration during push backs until the engines started and run.
(I usually sit next to the engine)
I could feel and see the engine vibrating even during idle.
That is indicative of all 777, those engines are massive and takes a lot of power to start. So even the GE 90 vibrates the whole aircraft.
this is part of a redundant system that is paired with the shrieking woman alarm on the plane. the shrieking woman alarm has a history of giving false positive results during turbulence, so this helps to mediate that somewhat.
🤣🤣🤣🤣 you win the internet for today my friend
7:10 while borescoping how do we rotate the engine? Is there any lever or any mechanism for that purpose?
At 7:52 why are some bolts missing?🙂
There is a crank pad on the AGB (accessory gear box) it’s a cover plate we take off and there’s a slot there where we can put a tool to rotate the engine via the gearbox. The missing bolt is not a missing bolt.. it’s also a slot for tooling to remove the Spinner. 👍
Also should talk about blade engine wash. To improve blade efficienty. Only problem is after it soaks and forgottenly doesn't get washed off..next flight, smells like the engine is burning up..fills cabin..not good
I’ll make a separate video just for that, engine washes are very common, and the primary reason is to basically improve the efficiency of the compressor and turbine,. Basically to clean up all the coking and debris from the core of the engine. And that is correct if proper procedure is not followed through, and proper lines are not capped off. There will be a smell in the cabin.
Overall however..a great explaination
Is that How Its Made soundtrack?
Anyway Stig what do you think about A321 NEO Engine vibration issue and how does AA handle it?
Yup that is the how it’s made sounds. And AA doesn’t have vibration issues on our fleet. Our Neos have the CFM LEAP 1A. The PW1000 is the one with the vibration problem alongside many other issues.
At the end of the video I noticed some bolts missing from the spinner cone, what's up with that? There seem to be four groups of three bolts, with one bolt missing from the center of each. So that theoretically shouldn't actually shift the center of mass from the middle, but less bolts does mean lower yield strength for the assembly... Are those bolts meant to be missing?
Those aren’t missing bolts, those are actually for tooling to remove the spinner. You put bolts in there in order to release the spinner from the hub.
How many hours does it take to replace the blades on say a 737 or an A320? And is this something that can be done on the tarmac or does this have to be done in a hanger?
In a hangar and if no damage is found you can do it in an 8 or 10 hour shift no problem.
Usually best to do it in the hangar, although I have done it outside. No more than 7-9 hours and depending on the crew you’re working with.
Yup exactly. But when damage is found it opens a new can of worms 😅
When the guy is underneath the spinning engine at 3:25, would he get sucked in if he got too close to the front/intake?
That guy is me under the engine and no I will not get sucked in because I’m away from the ingestion zone. I stay away from the from and back. Those are the dangerous areas.
Is it possible to identify the possible source of the vibration based on the particular vibration frequency measured?
Yes, the engine parameters, as well as the computer systems will usually pinpoint where the vibration is coming from
After a bird strike, what checks are performed?
It depends where the bird hit. When talking engines it depends whether there's evidence it went into the engine core or not. If it hit just the fan and went around the bypass section the fan blades get looked at. If there's evidence it went into the core not only are the fan blades inspected but the borescope plugs are opened up and the inside of the engine is checked. Usually if you have a confirmed birdstrike with core strike depending on the size of the bird and the damage it did you're looking at an engine change and rebuild.
Sometimes and I've seen this mind you birdstrikes have happened with core ingestion and after pulling the plugs no damage was found.
Like i said, it depends on the size of the bird, where it hit, how hard, etc. Lot of variability that makes every one unique.
Obviously when you are landing and you suck big bird into your engine it's going to cause a lot more havoc than if you sucked in a pigeon and I swear with some of them I jokingly asked if they hit big bird flying around out there because I've seen some bad ones.
Oh ya. I know what you mean. Some nasty ones I have encountered as well. As for the inspection part.. if we have a hit our job cards tell us to do inspections on the whole aircraft regardless of where it hits. They basically want to eliminate any possibility of other birds. They assume if there was one then there could be more.. so inspection of the whole aircraft and all engines.
Greetings Stig, can you describe why the main blades are hollow?
Not all fan blades are hollow. There are some designs such are the V2500 engine blades that have a small pocket of hollow space that is gas filled. This is because how the blade was manufactured and designed. Its ability to take those particular shapes and retain its strength.
@@StigAviation Thank you! Gee, I'm learning with this. I may become a technician haha🙂
Curious... I'm a Naval engineer who operated LM2500 engines for propulsion!
We had to do a "Water Wash" nightly on off line engines! Using hot water and a solvent... sprayed into engine while revving up engines with starters... do airliners ever do that?
Yes indeed we do. We also call it an engine wash, we have very specific water (I believe is heavy water) and spray it into the core while it dry motors. This helps the blade clean on LPT and HPT. Cleans up all the coking and improves the engine’s efficiency.
@StigAviation one thing that shocked me when I first started working on the turbines was that without doing frequent water washes... the blades aren't loose... they don't clink when ya turn it!
Which they're supposed to do! And if they dont... it causes vibration issues and much faster wear n tear on the roots... requiring blade changes much more often!
At least this is so on marine turbines!
@@StigAviation Thanks for the replies! Absolutely loving your videos!!! Wish I'd have converted to your specialty when I retired from the Navy!
How do they balance it?
Blades usually come pre-balanced from manufacturer/overhaul shops. When we get them we follow the manuals to install new blades in their respective positions for perfect balance. Then we run the engine to check for the vibration
I wonder if those pilot's of that Southwest 737 noticed vibration before the engine blew up
I guarantee you they felt it.
Just FYI.. this wrench is fantastic but...one day i will explain how to make the "perfect" landing. I call the touchdown so smooth you "fool" the speedbrake from auto extending,,even when auto armed. And yes, it can be done,,a wet Runway also helps 😮😊
Well, I won’t be flying in airplanes anytime soon that’s for sure, I just stick to fixing. 👍
Is that the “how stuffs made” theme in the background?
Yup. It is 👍
Most importantly is to never OUTSOURCE NEVER
Spoken like a true union member. I agree. 👌
Am I the only one that hears the "How its made" theme music in the background? 👀
Nope. You ain’t the only one. I love that show. Thanks for watching 👍
Stigster; Who from your company makes the decision solely to dead line a bird due to a newly discovered mechanical safety fault on the ramp?
The mechanic, me, we are the final authority to ground an aircraft, if I say the aircraft is not airworthy, and I know it’s not safe to fly then I will not allow it to fly. Not my supervisors, not my crew chiefs, not anyone else, if I see a problem, I will document it, and I will make sure That that aircraft gets fixed before it flies. otherwise it will sit on the ground until I say so or the next shift fixes the issue.
I have a blade from a T55-L7C. It ejected after an instant 140% N2 event.
140% 😳😳😳. Holy cow… that thing must have granaded itself.
Wow how much did they pay that dude to get under that running engine? That's scary.
You mean how much they paid me ? Because that me under that engine. 😅 and they pay me plenty. And it’s fun too 👍
3:35 makes me very nervous
What makes you nervous?
@@StigAviation someone being that close to an engine that looks like it’s doing more than idling
@@ruk2023-- ohh you mean when I’m under it while it’s running. Ya that’s totally normal. I know how to safely approach the engine while it’s at idle. We do this to leak check the engine.
The 737 max engines "bow". Can take up to 3 minutes to start...not exactly a confidence builder. The theory,,let's just spin it until it straightenes itself out😮
That usually happens on the first start of the day on a cold engine, but when the engine has been running, the whole day and aircraft comes through a turn, they seem to start up pretty quickly when it’s warmed up. The CFM LEAP 1A also does this.
Lock wire video please
I’m working on that one. I’ll get that for you soon. I’m trying to get the correct set up so I can so various examples of it. 👍