Tail Rotor Failure and autorotation

[aeio540]

I've seen several helicopter videos where a helicopter loses it's tail rotor and crashes. In 99% of these videos, it seems like the pilot is trying to land the helicopter vertically while it is spinning out of control. My question is what is the correct procedure for an unfortunate event like that.

 

I'm not a helicopter pilot but it would seem to me that if you lose the tail rotor, the best course of action is to decrease collective and throttle , which would eliminate the torque on the main rotor and stop or atleast slow down the spinning and attempt to perform an autorotation without the anti-torque pedals. I figure if you establish forward speed, the helicopter would "weathervane" into the oncoming wind and land somewhat safely.

 

Is this one of those things that would only work in a super ideal situation or if you are in forward flight?

 

If knowledge serves me right, the reason that the helicopter needs the tail rotor is only if work/power is applied to the MR but as long as it is spinning free under it's own inertia, it will not spin. This is the concept behind gyrocopters, the Fairey Rotodyne, and one of the Sud-Ouest Djinn(okay, these use tip jets but still no shaft power).

 

So are these other pilots doing something incorrect or is that just the way that it is handled, trying to land a spinning helicopter vertically.

 

Any answer is appreciated

 

I also watched Blackhawk Down the other day and started wondering.

Edited July 21, 2007 by aeio540

[RockyMountainPilot]

Very good obersvations. Yes, a pilot can weathervane the helicopter with forward speed, or chop the throttle and enter autorotation. The problem is that if in a hover when the tailrotor fails, a pilot may not feel entering autorotation is the best option and might try to gain forward speed to move over a better area to autorotate. When a helicopter isn't flying how it should, the pilot has to try and figure out what is wrong, and the best procedure. Sometimes they don't always do the best thing from an outside perspective, but from the pilots perspective, they are going to do everything possible to save lives. A lot of armchair pilots will say a pilot "shoulda" done this or that, but they can shudupp! It is not until one has experienced several emergencies in flight that you begin to gain a respect for the "OH S***" factor.

[aeio540]

Yeah, that's true. I'm not trying to say that it is easy to do. I mean, a pilot might decide that if he is hovering at 50 ft agl, he/she could bring it straight down with relative safety and trying to gain forward speed isn't always an option. Autorotating into a hangar is probably not the best idea either.

 

There were posts on another forum concerning proper procedure with a link to a video. It showed what looked like an OH-58 shoot through a valley, entered what seemed like a hover, a second later it seem to lose massive rotor RPM and crash. The subsequent replies stated that there is absolutely nothing one can do when the tail rotor fails except crash and that training never covers much on tail rotor failure.

 

It would seem like it is something pretty important to just skip during training. I dunno, I feel the same way about spin-training in fixed wings.

[RockyMountainPilot]

The risk to reward for certain procedures doesn't pan out. I don't show anyone except CFI candidates touchdown autos because more aircraft are wrecked in practices touchdowns than in real ones. So, practicing TR failures is done sparingly because of the increased risk versus the likelyhood of actually having one. This is where a good simulator can help significantly.

[aeio540]

The risk to reward for certain procedures doesn't pan out. I don't show anyone except CFI candidates touchdown autos because more aircraft are wrecked in practices touchdowns than in real ones. So, practicing TR failures is done sparingly because of the increased risk versus the likelyhood of actually having one. This is where a good simulator can help significantly.

 

True, I believe some things can not always be covered with actual behind-the-stick training. I just wonder if there is any mention other than "Dead End". I had an instructor tell me that if I entered a spin, it would be unrecoverable and there was nothing I could do. I feel that a view like that is pretty extreme, especially after I learning how to enter and recover from a spin in actual training.

 

Atleast mention of proper procedures being available outside of the scope of PPL training should be presented. Not that there is nothing you can do except carry a gun with you in case things go bad to end it quick.

 

You do make a point though, there would be alot of wrecked equipment.

[DonRow]

Well that depends, was it catastrophic or stuck peddle? You can train for stuck peddle but when it comes down to catastrophic you can't train for it. Coming from experience it's very stressful lets put it that way. Number 1 you try to fly the helicopter, then you start to nose over cause your CG is outside the envolope, but you think "hey if I drop the power meaning collective that will reduce the tourqe" and it dose. Which will reduce or elimenate the turn or spin. The best thing you can do is to just fly the helicopter. Thats what I did, and never give up. You can turn a situation from real bad to good.

 

You can not simulate a catastrophic T/R failure! Even a old time MD instructor pilot told me that. It's something that I don't wish on anybody. All you can do is train hard.

[Mike Murphy]

Once you lose T/R thrust and the bird swaps ends your airspeed is nowhere near where it needs to be to shoot an auto. You are almost certainly in the high/slow area of the HV diagram. In larger helos, the centrifugal force often makes it impossible to get to the power levers to secure the engines....ride 'em cowboy and hit as level as possible.