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Medium Tail Rotor Drive Failure

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Just my humble Engineers opinion.

If you have a drive failure the chances of escaping unscathed are quite remote. There was a 212 a few years back that belonged to a B.C. company where the No. 1 flex coupling let go in forward flight. The Pilot didn't make it, unfortunately.


I worked with a Pilot several years ago and he described to me his T/R drive failure in a 205. I wil quote his words as far as I can remember.


"I was picking a log up with a 100ft. line when in a heartbeat I was spinning like ****. Forget all the stuff you see in movies where the Pilot is fighting to regain control, that's bullsh-t!!. My upper torso and arms were pasted in the bubble and I could not move a muscle. I could not reach the controls!!. As quick as it happened it was over and the machine was on its back in the trees with me under it."


He was pretty banged up, but lived to fly again. Sure glad he made it, he was a wonderful guy to work with as are "most" Pilots.


The cause of the failure was the tunnel AD had not been done after a starter/generator change and the inside of the tunnel had carved its way slowly through the forward drive shaft.


I would think that if you have a drive failure in any type of helicopter it's pretty much over. How many of us have seen the S-58 video from down south. (intermediate gearbox failure) Or remember the Langley Company's S-58 failure a few years back (blade spindle embrittlement)


By the way, we have 7 inches of snow on the ground in Powell River right now and it's still coming down hard! WTF, this is supposed to be The Sunshine Coast!! But that's OK. I have lots of Scotch, a full larder, my Sweetie, and my dog. Life IS good! :punk: :punk:

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It just so happens, said pilot, sitting 2 feet in front of me is going to give me my 205 check out starting today! If the snow stops. He told me the story a month ago in Fredericton after suffering every failure known to the Bell gods in the 412 simulator. It was true, It was the chain. Funny story is, he flew it right back to base at pickle lake, the boss said " good on ya chum' Grab that 204 over there and get back and finish that bloody drill move! he shows up back at staging with a new 204, the engineer was kinda wondering WTF? How did? Where'd the other one go??


Cool/ funny story.


Any comments there Mr hook dangler?

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I must be getting old because Ican only recall two chain failures at Midwest when I worked for them from 1976 to 1997 .I don't recall this incident and I was in Pickle for most of the time working on the 204s.As the tale goes it may be true as at one time Midwest was running 8 or 9 204's.I may have been off on time off then. after several years of working in places like Pickle/Hidden Bay ,Sask. Ican honestly tell you that you can shove those places where the sun don't shine.

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Great Slave had a 204 tail rotor pitch change housing/nut fail while lifting a loaded bucket out of the lake in front of the Buffalo Narrows firecamp. The pilot got her moving forward, circled around to the yard and somehow dumped the water, then the bucket (without damaging it) before flying away for another appoach to the grass for a run-on.


No damage, no drama, just good hands and years of experience.


That said, it was a failure of the pitch change mechanism and not the tail rotor drive. You're just trying to mitigate the crash damage if the drive fails, and good luck to ya. That's why I watch those couplings (especially the transmission output, since it gets the most angulation under load) like a fat kid watches a smartie.

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rainman...say high to dave j for me and tell him the next time he is in freddy to give me a call...been down here in saint john for 8 years...haven't seen bo judley in a long time...since old midwest days :punk: otooley...think penner or hosebag was there when it happened...I was in red lake...happy trails...pottsy

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I'm glad to see this thread, we should always be thinking about our skills!!!



So lets think about this one, the engine's only job is to turn the rotor. Lets use my G4 as the example, thats a total of 260 hp when at 100%. For every action there is a equal and opposite reaction, so 130 hp will be acting to rotate the fuselage. ( I can't imagine the rotational power of the 214 Rick had to deal with, experience is worth it's weight in gold. good job man!! Thats why old pilots all have beer guts!! )


When air flows over the horizontal stabilizer and airframe it creates a force. How fast would you have to go to overcome your current power setting. Speed does so much more then weather ****, it allows us to lower the collective. A half loaded 206 will sustain level flight at 60 mph with a power setting of 50 - 60 % torque. That reduces the rotational torque by 40 - 50% !! Effective translational lift gives us approx a 20% increase in lift and allows us to lower collective.


The T/R drive system is most likely to fail at full power, and no air speed. Because it requires the largest power output.



So pull it into a high hover, Kick full right pedal ( left for the Europeans ) and see if you can get the collective low enough and the air speed high enough to equal out the force. You must react instantly, a strong wind sure helps.



One of the biggest advantages of instructing is being able to go out and experiment. One truth comes out again and again, the same basic principles that apply to a pedal failure also apply to an approach to a confined area, air speed controls power. There is more power in your right hand than you will ever find in your left.




This is me in front of my laptop sippin' a beer, this in now way constitutes the approval for you to go try it. If you do, don't tell your boss I told you to...





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