tail rotor failure at hover
 

wat i think as a point of discussion is tail rotor failure is the gravest of all the emergencies.pl fwd some valuble inputs to how to recover successfully recover from a TR Failure at hover. regards

er...land?

immediately !!!

G

before the rate of rotation gets too high!

But don't get confused with Loss of Tail Rotor Effectiveness. Shame to dump a perfectly serviceable aircraft on the ground. Of course better to be on your side with a serviceable tail rotor than still flying with a broken one - but knowledge of your aircraft should help work out what's happened.

If in a Gazelle or other Fenestron aircraft you need to understand how a Fenestron puts out its power so you can fly it appropriately and not getting into what is incorrectly called Fenestron stall. I know the Guimbal service letter on the topic is excellent if you can get your hands on it.

You might want to cut the power first, it slows down the spinning sensation.

First-what is a "tail rotor failure"?

Pitch link failure?
Tail rotor drive shaft failure?
High Power failure?
Low Power failure?

It makes a HUGE difference.....

But if you´re talking about a full tail rotor (thrust) failure:
Autorotate-IMMEDIATELY.

There is NO "fly away" possible...

Had one in the Zagross mountains in 1970 just coming into the hover in a AB204. Tail drive shaft coupling went. Lever down but still spun 270 degrees and bounced twice from what I can remember:ok: The aircraft remained upright and we all climbed out unhurt

Read the manual and train one more time...

I'm sure not everyone would agree with that statement.

I had six T/R failures in the RotorWay 162POS, uh, I mean 162F. Most of them were recoverable by getting the tailrotor to stop stalling (yes it can) and nursing it back.
The most exciting was one in which I didn't take it away from the student until it had already wandered halfway off the asphalt and was halfway over the desert - a drop of about six inches.
If I'd chopped it then we'd have hit while turning on that uneven surface and rolled.
So I had to keep it in the air, while keeping the cyclic pointed East, until I had black blur on both sides. Then I chopped it and sat it down. No worries.
They told me later that the guys in the sales office were diving under their desks as I came spinning toward their floor-to-ceiling window.
Fun! ;)

Nursing????
 

Hey Aerobot....a Tail-Rotor failure; recoverable by stopping stalling? WTF & I always thought a TR failure meant loss of thrust due to the TR drive-shaft or some other failure which could be recovered by closing the throttle & holding off ground contact with collective, hopefully till the spinning stopped. Hmmmmm :\

Happy Happy :ok:

AKA loss of tail rotor effectiveness. :rolleyes:

@ Two´s in

you don´t have time to cut power if the tail rotor quits working - just slam the collective down, if you wan´t to live another day.....

Not sure that's a good idea. Unless you have throttle levers and can not get to them or are flying someone else's machine and don't care about damaging it.

In HIGE: land immediately.

In HOGE: how about pointing the cyclic towards a fixed point of the horizon, which means - with the cabin spinning - moving the cyclic in a counter rotating cyclic fashion, so that it points "away from tree/building/offshore-rig" towards the "desired direction". :8

W/o touchng the pitch the rotormast should inclinde towards "desired direction",
the a/c will pick up speed in that direction, and weather vane effect will stop rotation.
continue run on landing according to AFM. :hmm:

Never done that of course, never heard of someone trying it either := ,
but RC-helo pilots do a butt load of maneouvers with the cabin deliberately spinning,
hence they're rused to "rotating the cyclic". search for "prio",
Paul's Helicopter Pages see Piroloop Paul's Helicopter Pages

Then again they don't sit inside a spinning cabin...

It is important to mention to never let the turning rate build up so high that the pilot would lose situational awareness and/or dificulty to reach the controls of the helicopter. The pilot must act quickly and promptly to avoid this scenario, so one must know how the aircraft would respond to different emergencies such as tail rotor failure, stuck controls (with positive and negative pitch) and LTE.

In most helicopters....does the thrust produced by a full application of right pedal(American direction of rotation) equal or exceed the amount of torque (turning force) of the Main Rotor System in a hovering aircraft?

Question being....if a full right pedal application equals or exceeds the Turning Moment of the Main Rotor system....one could test various techniques to control the spinning of the aircraft.

I guess if one were brave enough....one could apply full right pedal at a Hover and attempt to fly away and establish some sort of controlled flight with the nose of the aircraft yawed from the direction of flight.

In flight, we know if one reduces the MR RPM to the bottom of the Green Arc (Power On Limit) the resulting yaw is minimized or removed.

You CFS Rotor Scholars might answer the question about the amount of Torque applied to the Rotor System when RPM is reduced....does the Torque decrease with the decrease in RPM even though more pitch is applied to the Rotor? In my younger days I would offer my own calculations but I am well beyond that in my old age. CRS (Can't Remember Squat) has firmly set in and prevents me from throwing out the answer.

Any thoughts on this?(The flying parts...not my CRS!)


Brother John Dixon or Professor Lappos would be great sources of thinking on this!

is a very good publication to read.

Unfortunately, since the CAA website was changed, I cant find the download link.

Edit: now found it!

http://publicapps.caa.co.uk/modalapp...detail&id=1127

SASless, I tend to think that there are too many variables to give a "one size fits all" answer to your question.

During my time as a simulator instructor we were tasked by Boscombe Down to experiment with tail rotor malfunctions in order to provide further guidance on tail rotor failures for RAF Puma pilots.

Until that time the only tail rotor "failure" covered in the FRC checklist was drive shaft failiure. We flew many different scenarios in the sim which enabled us to provide guidance on other types of failures. We were careful not to give actual drills to follow by rote because correct diagnosis of the actual type of malfunction was critical and we were "flying" a simulator, not the real aircraft and the response of the sim may not have been exactly as per the real airframe.

The FRCs said that in the event of a tail rotor driveshaft failure the pilot should "find a speed and power combination which will enable the aircraft to be flown to a suitable area for an engine off landing" - total rubbish! It isn't safely possible to do that in a Puma; the only suitable speed power combination with no driveshaft is nil power and best auto speed.

I do know that we probably saved one aircraft after it suffered a tail rotor pitch control failure, rather than a drive shaft failure. Using the guidance we provided and later taught, the aircraft was successfully ditched in the North Sea. The crew escaped unscathed and the aircraft was recovered, despite floats not being fitted. The pilot told us that had he not received the training we provided he would have just pulled both throttles, which would probably have caused total loss of aircraft control in the circumstances.