tail rotor failure in fwd flt

[gootybalajiniranjan]

why engine and rotor rpm needles split in this emergency and which one will be more rotor or engrpm

why dont we shut off the engine immediately after the emergency

request

[DonQuixote23]

There are many types of TR failures but I suppose you mean loss of drive or failure of the actual tail rotor.
The Engine and rotor rpm needles will NOT split if you have a failure like these (unless you enter autorotation, which is the recommended action in some helicopters).


Also, you will have a hard time to get the Engine RPM to be higher than rotor unless the clutch or freewheeling unit fail.

[Soave_Pilot]

why dont we shut off the engine immediately after the emergency

I ask you:
Why give yourself another emergency in a emergency situation?


As Nick Lappos once said in this forum:
"I suggest that if you experience loss of tail thrust in cruise flight, (sharp right yaw in an American helo, left yaw in a French or Russian machine -- I will use the American convention below) get control of the yaw situation first. Lower the collective immediately enough to stop all yaw and allow a steady state descent. Carefully guard your airspeed, try to stay at a high speed autorotative glide speed (about 1.5 Vy in most helos). If all is going poorly, go to full auto and take your chances on the landing. If the glide looks good and yaw is well behaved, you MIGHT try to gently increase power to reduce the rate of descent, while maintaining speed. The aircraft will start to yaw right as power is applied, so you must cross control by applying left bank to keep the heading stabilized. You will probably have to go more nose down because you have much more drag, and you must watch for two big danger signs - excessive yaw like a flat spin, and loss of airspeed indications, where the pitot probe might give up working in the big sideslip. At the first sign of either danger sign, lower the collective pitch and the nose to get the torque down and the speed up.

For most helos, you will not be able to get to level flight because to torque you need will produce an excessive sideslip or even a flat spin (the ultimate problem in all this test pilot heroic stuff). Settle for a reduced rate of descent, since it really helps you extend your choice of landing areas. If you can get to as little as 750 feet per minute descent, and you are doing 100 knots, you can travel 3 miles from 1500 feet, almost 7 miles from 3000.

At the bottom, transition to a reduced collective flare, and make a part auto-part running landing. Don't increase the collective at touchdown unless you have decoupled the engines, as the sudden torque rise will create a big spin, and a real crack-up.

The skills needed to fly out of an anti-torque failure are not trivial, and most pilots are best served by thinking and performing an autorotation, period."



This should enlighten you.
SP

[Arm out the window]

Although if you only have landing areas available where a run-on landing will likely result in a crash (rough, boggy, treed, excessive slope etc) then I think the engine-off zero speed auto will be the most survivable.

[Paul Cantrell]

This brings up a question I have about simulating TR failure in forward flight. Generally, I'll take my feet off the pedals. One would reasonably expect air loads to drive the TR to flat pitch. I usually tap on the non-power pedal a few times to help this happen. So, at that point one would expect that the TR is not producing thrust in either direction.

However, this does not seem to produce as much yaw as I would expect having heard people describe TR failures. One reason I suspect is that I have read that the turning TR acts like a vertical stabilizer of the same size, i.e. although it's not producing thrust, it is still producing an anti-torque force in forward flight.

I would think that to simulate the failure more accurately, I'll need to hold some more non-power pedal. My question is: how much?

Since Nick's quoted story talks about not being able to maintain altitude, and my experience in R22/R44/R66/B206 is that with flat TR pitch I can cruise and even climb, I'm guessing the answer is "quite a bit".

Anyone with experience care to comment on how much non-power pedal would be an accurate simulation of a non-rotating TR?

[ShyTorque]

PC, It would be pointless to answer, even if anyone knew, because there are many variables involved and every helicopter type is likely to be quite different in any case.

[whoknows idont]

Originally Posted by gootybalajiniranjan

why engine and rotor rpm needles split in this emergency and which one will be more rotor or engrpm

Clearly you are not a helicopter pilot. And clearly you have not understood how the freewheel works.

[BOBAKAT]

In case of TR failure, 2 main cases :

1/lost of the "control" of the TR

2/ lost of the TR himself

the 2 cases are very different for you in flight and for recovery.


first case :
nearly nothing happen if you have the cruise speed. Just, you can't move the nose of your helicopter...
The pitch of TR blade go to neutral by himself
Depend your flight manual, you have to make an autorotation landing or sliding or rolling landing or other....

second case is the worst...
no more trust on the TR = the nose go down left or down right depend the clock wise or counter clockwise of the main rotor.
Your instrument Speed indicator, altimeter, variometer, are totally false due to frame position in the air : static and dynamic make whistle.
Autorotation is mandatory, but take your time...

[DonQuixote23]

Paul - with the TR in flat pitch, when you get an angle of yaw then the TR is getting an amount of induced airflow and hence angle of attack and the TR is producing thrust again (similar to the main rotor in autorotation). So flat pitch would behave very different to a complete loss of the TR or a TR that is not rotating.

[chopjock]

I had a tail rotor gearbox break up in flight on the Enstrom (it remained in place though). It was a non event really, I continued flight out of trim until a suitable landing site came along and just carried out a gentle auto rotation. No real problem.

[MightyGem]

If the glide looks good and yaw is well behaved, you MIGHT try to gently increase power to reduce the rate of descent, while maintaining speed. The aircraft will start to yaw right as power is applied, so you must cross control by applying left bank to keep the heading stabilized. You will probably have to go more nose down because you have much more drag

That's how we coped in the Lynx Sim. Ended up about 30 deg bank and 30 deg nose down. Whether it would work for real...

[mixing lever]

AH-64 TR Loss

Back in 2007-08 an AH-64D lost its entire tail rotor and TR gearbox while escorting a UH-60 in Afghanistan. The instructor in the front seat was able to control the aircraft, shoot an approach that was deemed too fast, make a go-around, and subsequently make a second run-on landing while keeping the aircraft under control. He flew UH-60s in the civilian world and apparently used the annual simulator training periods to conduct many tail rotor malfunction approaches. Simulator training does have its value. Hats off to the instructor.