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-   -   Tailrotor failure - is it always unrecoverable ? (https://www.pprune.org/rotorheads/599736-tailrotor-failure-always-unrecoverable.html)

Thomas coupling 21st Sep 2017 14:57

http://www.pprune.org/rotorheads/508...ght=tail+rotor

megan 22nd Sep 2017 01:02

Was extremely surprised at the training available from even highly respected organisations. In the sim, single pilot -76, drive failure in the hover, climb the rotating aircraft to 1,000 ft, nose over to gain airspeed, and fly to a suitable landing area. Assumed performance permitting. Having only ever seen one drive failure* in my life thought it suss teaching. Perhaps it is possible, I don't know.

* Huey stuck its tail into the ground in the flare at slow speed. That sucker whipped around so fast I found it unbelievable. Trouble was the tail took out permanently some of the troops waiting.

Ascend Charlie 22nd Sep 2017 06:34


In the sim, single pilot -76, drive failure in the hover, climb the rotating aircraft to 1,000 ft, nose over to gain airspeed, and fly to a suitable landing area. Assumed performance permitting.
Megan, I hope you were suitably disappointed that they said such a thing was possible?

Your brain would ooze out your ears while pulling pitch to get to 1000', and the "roll coupling" effect where the fuselage no longer stays level and the spin goes more vertical than horizontal would disorient even our mate Nick.

When I did the sim on the 76B at West Palm, the only thing taught for a drive failure from any altitude was throttles-idle auto. I was able to show the sim instructor a different technique (from Huey days, and applying to B206 as well) leading to a running landing - had to show it to him twice before he really believed it - but he insisted that the tried-and-true auto be performed to pass the course.

[email protected] 22nd Sep 2017 07:46

The only problem with relying 100% on techniques 'perfected' in the sim is that the aircraft modelling might not be accurate enough to 'prove' the technique in the real world.

Having said that, I have valued all the sim training I have received over the years but hope I never have to try it out for real!

Thomas coupling 22nd Sep 2017 09:37

Everyone needs to be aware that sim programmes rely on OEM algorithms to simulate TR failures et al.
Currently it has been found that one major global helicopter manufacturer has not got his ducks in a row when it comes to the "data in" on their TR programme.

It has thrown up some serious questions by test pilots on the efficacy of it all.

The ONLY way to 'manage one's expectations' when it comes to handling TRF and TRCF is to talk to seasoned vets and those who have had one.

ShyTorque 22nd Sep 2017 09:58

Having been part of the team that set up one of the RAF's first helicopter sim. training programmes, I was pleased to hear feedback from one of our pilots who stated that he was of the opinion his life was saved by guidance and training given to him regarding T/R malfunctions.

His aircraft suffered a tail rotor control failure over the sea (limited tail rotor power). He managed to spiral down and safely ditch the aircraft, which was later recovered. He said that without the training he would probably have chopped the engines, which would have been a big mistake; things would undoubtably have gone very badly wrong.

I also know of another pilot (of a non RAF Puma, not given our training) who suffered a tail rotor drive failure in the 140 kt cruise. He initially tried to slow down without chopping the engines but it began to go wrong so he accelerated back to 140 kts, flew back to an airfield and carried out a running landing at that speed. He apparently got away with it, too!

gulliBell 22nd Sep 2017 10:21


Originally Posted by megan (Post 9899964)
..In the sim, single pilot -76, drive failure in the hover, climb the rotating aircraft to 1,000 ft, nose over to gain airspeed, and fly to a suitable landing area..

Having done, and seen demonstrated, many TR drive failure in S76 sim, nothing has ever come close to that technique mentioned there. The only way to carry out a successful recovery from TR drive failure in S76 sim is to follow the procedure as per the RFM. Real life might be different, but I'd be very surprised if any S76 pilot who climbed to a 1000' from a real TR fail in hover would have any sensibilities left to do anything after such a wild ride which it certainly would be. Especially in a B or C variant.

Thomas coupling 22nd Sep 2017 11:26

In the course of my varied professional life, I have been fortunate to debrief literally dozens of pilots who have survived various catastrophic experiences. Apart from making my decision making process more comprehensive, it has made others more aware as I cascaded this information at every opportunity.
In this particualr instance (TRF and TRCF) research, revision and calm - were the common factors with all the debriefers.

Shy - I'm struggling with a 140+Knot running landing on a narrow tricycle undercarriage I am afraid - it's just not going to happen.

And I concur with gullibell - no sane pilot would ever 'knownigly' transition out of a hover after a real TR failure because he would be completely disorientated within seconds as the G foces and dizziness and blurred vision overcame him - again this leaves a lot to be believed.

A TRF in the hover is dead easy - lower the lever. The end.

It requires little or no thinking. You simply take your chance with the impact.
[Chopping throttles and cushioning the landing is a very very nice luxury and tends to be the option available only to the lightning quick and very calm driver).

ShyTorque 22nd Sep 2017 12:14


Shy - I'm struggling with a 140+Knot running landing on a narrow tricycle undercarriage I am afraid - it's just not going to happen.
Unfortunately, for once, you are wrong - it did.

However, I would definitely NOT recommend the technique, for the same reasons you quoted!

Thomas coupling 22nd Sep 2017 12:27

Shy - so you want other peers to believe that a Puma touched down at 162mph with a major malfunction in the knowledge that the very instant he lowered the lever (to stay on the runway) his aircraft would have commenced a side slip due to the yaw differential?

C'mon Shy - perleeeeeeze smell the coffee.:rolleyes:

megan 22nd Sep 2017 13:06


When I did the sim on the 76B at West Palm, the only thing taught for a drive failure from any altitude was throttles-idle auto
Twas taught in that very same building AC, A sim.

A thread I started some time ago.

http://www.pprune.org/rotorheads/579...r-failure.html

Page 46 of the attached, Apache loss of tail drive.

https://www.raf.mod.uk/rafcms/mediaf...6F60697008.pdf

Wessex drive failure.



and



and


I'm struggling with a 140+Knot running landing on a narrow tricycle undercarriage
Recall a 76 making a somewhat high speed landing as a result of T/R issues. Drive or control don't recall, went off the side of RW, kept it upright. Written up in R & W I think, many years ago.

SASless 22nd Sep 2017 14:32


Originally Posted by Thomas coupling (Post 9900421)
Shy - so you want other peers to believe that a Puma touched down at 162mph with a major malfunction in the knowledge that the very instant he lowered the lever (to stay on the runway) his aircraft would have commenced a side slip due to the yaw differential?

C'mon Shy - perleeeeeeze smell the coffee.:rolleyes:


I cannot attest to the particular event but I know of similar landings post tail rotor problems.

At one Operator I had the misfortune to hire on with.....flying BK's....the procedure taught was exactly that. In training I saw Approach speeds in excess of 100 KTS.....but no touch downs.

When I inquired if the TC was making a very bad joke....he had quite a sense of humor failure and demanded to know what I would do differently.

Up we went...established the same setup....and I did an autoration and accepted some yawning at the bottom with zero ground speed.....which seems far safer an arrival than getting to the bottom at over a hundred knots ground speed and full chat on the rotor system....very limited yaw control....and thoughts that following through with Cyclic might prove to be a bit of a challenge!

But then what do I know?

SASless 22nd Sep 2017 14:39


Originally Posted by pba_target (Post 9898878)
I never understood the obsession with tail rotors.... Just fly a tandem rotor, at least then all the bits that can break aren't in places where you are going to put them into a tree...



From experience.....that is not a true statement!:(

John R81 22nd Sep 2017 15:41

Don't know about 140knt - I can't go that fast.

I did however once do a 70knt running landing in a skid-equipped machine; scary beyond belief.

SASless 22nd Sep 2017 23:35

I once talked with the pilot of the 58T doing the Underslung Load....he said he was trying to get the aircraft to a cleared area and was accepting the yawing and once close enough to the clearing....he cut the Throttles...and entered autorotation and when he tried to move forward a bit....the nose dropped a bit too much and that is when it all went pear shaped.

He was not seriously hurt.....and he did opine he felt very badly about the damage to the aircraft.

Hot and Hi 23rd Sep 2017 08:55


Originally Posted by SASless (Post 9901053)
He was not seriously hurt.....and he did opine he felt very badly about the damage to the aircraft.

And I feel bad that the guys carrying him out of the wreck dropped him twice...

[email protected] 23rd Sep 2017 11:15

TC - very fast running landings are quite possible in tricycle undercarriage aircraft with TR malfunctions as long as you have enough real-estate to make a very gradual lowering of the lever once the wheels are on.

A lockable nose-wheel helps directional stability and lateral cyclic combined with differential braking help keep you straight-ish.

Not saying you would stay on the runway but I wouldn't dismiss Shy's story out of hand:ok:

treadigraph 23rd Sep 2017 15:16

A Met Police Bell 222 did a run on landing at Hatfield after a tail rotor failure many years ago. I think it rolled on to its side but the crew were ok.

Thomas coupling 23rd Sep 2017 21:44

Crab - howdie.
Have you been on the crystal meth too?

Just picture a running landing at 160mph - just for a few seconds will you?

Picture a runway of - on average 2 miles long. You can't use brakes at that speed and as you lower the lever you will need someone standing between the pilots bringing the SSL's back at a very co-ordinated and precise rate according to your instructions.
The helo presently is travelling at 2.7 miles per minute. You have 80 seconds to stop before you run out of runway. Any side slip will result in a catastrophic rollover. Once the cab starts to deviate from anything other than straight ahead at any considerable speed, your corrections will almost certainly cause divergence and pilot oscillations.

You would only survive because of pure unadulterated luck. Choosing to do this voluntarily is crass stupidity and gross ignorance of the limits of your a/c.
Low speed handling checks at height (1000') would offer you the ability to atleast halve this speed whilst still maintaining directional control.
The comment from Shy that it "started to go wrong when he slowed down", suggests mishandling.
Next time you're airborne, shoot an approach to your runway at your Vmax and let me know what it feels like if you had to follow thru and land without brakes and a dodgy steering wheel!!!!!

SASless 24th Sep 2017 01:27

Amen! TC gets a Gold Star!

If one is confronted with such an option.....why not do an autorotation as I suggested?

Is not the problem too little “tail rotor thrust”?


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