AutoRotation

[helopilot2be]

You are flying along and the engine quits, you need to auto right now. That is all the information you are given. What is your FIRST control input?

 

 

 

Chris

[zero610]

Down collective to preserve rotor RPM.

[kodoz]

You are flying along and the engine quits, you need to auto right now. That is all the information you are given. What is your FIRST control input?

 

Chris

 

Trick question. You will instinctively correct yaw with a pedal input. You will then be slamming that collective down and correcting your attitude. fail to do any of those things and the auto isn't going to work out ideally.

[Spirit of '69]

Good timing. I start autos Friday!

[r22butters]

You are flying along and the engine quits, you need to auto right now. That is all the information you are given. What is your FIRST control input?

 

 

 

Chris

 

If all those "throttle chops" we did during training did their job, I'll be slamming the Collective down before I even know what hit me!

Edited April 7, 2011 by r22butters

[EAGLE1]

I say there is no "first" input. You should simultaneously lower the collective, aft cyclic and trim with the pedals. You should accomplish this all quickly and smoothly. You are using both arms and feet which can all act independently and simultaneously of one another.

[MileHi480B]

Tighten the sphincter.

[rodrop]

I vote lower the collective

[Scarab]

Tighten the sphincter.

 

I think that is automatic in an auto.

 

My Grizzled Viet Nam chopper pilot turned instructor explained the maneuver as simple transition from one form of flight to another, ie powered to unpowered. Not a 'Panic' maneuver but a simple quick transition. That frame of mind helped me a lot.

[ADRidge]

I say there is no "first" input. You should simultaneously lower the collective, aft cyclic and trim with the pedals. You should accomplish this all quickly and smoothly. You are using both arms and feet which can all act independently and simultaneously of one another.

 

This. Basically it's a three-way tie between "Down", "Right" and "Aft". At the very least, a two-way tie between "Down" and "Right".

[rodrop]

Ok, go easy on me cause I am not an expert but I thought--

lower collective first

cause you dont have to use right pedal (even though it is simultaneous) or aft cyclic until you lower collective. Right pedal is because you lowered collective and lessened your torque..aft cyclic is because when you lower collective the nose has a tendency to go down.

 

So, my vote is still lower collective because you dont really do the rest unless you lower the collective. (I guess you could do right pedal first and lower collective to balance it and you could aft cyclic and then lower collective to balance it..but... I think the lower collective is the first step).

 

Am I close?

[Trans Lift]

Right pedal is because you lowered collective and lessened your torque..

 

The torque is removed by the engine quitting, not by lowering the collective!

[Gomer Pylot]

When the engine quits, the torque stops immediately. The yaw will occur before anything else. The appropriate action will vary depending on the phase of flight, whether cruise, hover, on takeoff, on approach, or whatever. There is no one right answer here. You do whatever it takes to make the helicopter do what you need it to do. For instance, in an S76C++, if an engine quits on takeoff, you incease pitch, droop the rotor RPM to 90%, and hold that until you have Vtoss. It's counterintuitive, and takes practice to be able to do it, since we're all conditioned to lower collective, but with 2 (count 'em, two) FADECs per engine, you don't worry about overtemping or anything else, you just let the computers worry about the remaining engine, and keep it flying. In most twins, you will lower collective slightly, just enough to keep the good engine below limits, and keep flying. In a single, you're going down, but you have to keep it under control. Never apply lots of aft cyclic, or you might chop off the tailboom. It's a real possibility if you get too enthusiastic. The control movements will be almost simultaneous, as they should be for every maneuver. You have to keep the aircraft in trim, or your descent rate will get too high. You have to lower the collective, or your Nr will get too low, but this isn't necessarily the first action, depending on your altitude and airspeed. With enough altitude, you can recover rotor RPM. From a hover, you certainly don't want to lower the collective first, or you will bend a lot of metal. It always comes back to coordinated control movements, making the aircraft do exactly what you need it to do at the time, to accomplish a successful landing. In short, the question is a silly one, and there is no one correct answer.

Edited April 8, 2011 by Gomer Pylot

[rodrop]

The torque is removed by the engine quitting, not by lowering the collective!

I stand corrected ... darn it

[crashed_05]

Gomer Pylot said it very well. Depends on the situation. I've heard some argue that in fwd flight, applying aft cyclic as an initial reaction is more important than lowering collective. Again, I do agree that all these imputs are simultaneous reactions. But think about if your hand is away from the collective, messing with the radios or GPS, and your engine goes out. From the time it takes to get your hand back on the collective, you can be applying aft cyclic. Aft cyclic (flaring) increases rotor RPM a few ways...first, through coriolis effect, increasing the total rotor thrust increases the lift factor involved in coning and coning angles increase resulting in higher rotor RPM. Second, the total reaction (lift drag resultant)acts closer to the plane of rotation, which also increases your RPM. Even though there are higher angles of attack in the flare, which would tend to slow RPM, the re-orientation of the total reaction acting closer to the plane of rotation has the stronger effect, increasing RPM.

 

I'm pretty sure I got this knowledge from my Wagtendonk in the chapter on flares.

[helopilot2be]

. In short, the question is a silly one, and there is no one correct answer.

Sorry you feel that way. I was not trying to be silly. I had the question posed to me be a high high time pilot and instructor. Being trained in an R22 my immediate answer was down collective. When he told me I would be a lawndart, I wated to see how many others were trained the same way I was.

Thanks to all that provided their prospective.

Chris

[Gomer Pylot]

Sorry you feel that way. I was not trying to be silly. I had the question posed to me be a high high time pilot and instructor. Being trained in an R22 my immediate answer was down collective. When he told me I would be a lawndart, I wated to see how many others were trained the same way I was.

Thanks to all that provided their prospective.

Chris

I know you weren't trying to be silly, but I'll say it again, there is no one correct answer, just as with almost anything concerning flying, especially helicopters. To come to a question with only one correct answer, you have to be much, much more specific. I know your instructor is trying to teach you, and that question can make you think, but that's about all.

[r22butters]

...Being trained in an R22 my immediate answer was down collective. When he told me I would be a lawndart, I wated to see how many others were trained the same way I was.

 

Did he happen to say why you would "be a lawn dart"? Since down Collective is standard procedure for us Robbie guys.

[iChris]

You are flying along and the engine quits, you need to auto right now. That is all the information you are given. What is your FIRST control input?

Chris

 

As already stated the appropriate action in any emergency will vary depending on the phase of flight and total situation at that time; however, with respect to the question and the poster (helopilot2be), I assume you're in a single-engine helicopter flying at altitude at cruise airspeed. Lets turn the question around and ask, what is my main concern in this situation?

 

In a single-engine helicopter at altitude after the engine quits your main concern is maintaining a safe rotor RPM. The best way to do that is by lowering the collective and make the transition from power flight to autorotation. Once in autorotation, the upcoming air through the rotor will maintain rotor RPM and thrust. The loss of the potential energy is sacrificed and transferred into the rotors kinetic store as a result of the autorotation descent. When you're closer to mother earth, you can use the kinetic energy stored in airspeed and rotor RPM to arrest the rate of descent and forward speed to make a safe landing.

 

Remember; when the engine suddenly quits (single-engine helicopter), the rotor will begin to feed on its kinetic energy by slowing down to make up for the power loss. The so-called cyclic flare technique takes advantage of the kinetic energy stored in the forward airspeed. The flare transfers energy to the rotor by sacrificing forward airspeed; however, this only delays rotor decay 4 – 6 seconds at best. I've heard of UH-1 test were they could delay lowering collective and hold altitude for up to 9 seconds after a power chop with the flare technique.

 

Notwithstanding the cyclic flare technique, there just isn't enough energy stored in the airspeed and rotor kinetic pool to do more than delay the fact that the collective must be lowered when the engine quits in a single-engine helicopter at altitude.

 

Look at it this way; if you could make only one control input within the first 10 seconds after your engine quits in this situation, what would it be?

Edited April 12, 2011 by iChris

[1badz32]

I vote pull the ejection seat handle.... but thats just me.

[iChris]

Did he happen to say why you would "be a lawn dart"? Since down Collective is standard procedure for us Robbie guys.

 

 

If rotor RPM is allowed to decay passed a safe level and the helicopter starts to fall, It comes a point were recovery maybe impossible. The end result is the helicopter falls from the sky like a lawn-dart.

 

"As the helicopter begins to fall, the upward rushing air continues to increase the angle-of-attach on the slowly rotating blades, making recovery virtually impossible, even with full down collective." [ from SN-24]

 

Robinson Safety Notice SN-24

 

Robinson Safety Notice SN-10

Edited April 13, 2011 by iChris

[Joe85sti]

Depends on the helicopter.

 

R-22: Slam collective down!

 

Bell 212, 222, 205, etc: push right pedal, hit nrst on GPS, hit enter, then activate. Turn to bearing indicated by GPS, lower collective accordingly to reach airport selected, enter 45 degree downwind, or direct if tower allows. Hover to ramp, set down into wind!

[iChris]

-----------------

Edited April 13, 2011 by iChris

[r22butters]

If rotor RPM is allowed to decay passed a safe level and the helicopter starts to fall, It comes a point were recovery maybe impossible. The end result is the helicopter falls from the sky like a lawn-dart...

 

Actually, from the tone of his post, I was under the impression that the instructour had told him that first lowering the Collective(as we are taught in the R22)would turn him into a "lawn dart"?

(In his answer to an engine failure, he said "lower Collective",...to which the CFI said, "you'd become a lawn dart")

 

That's the question I was seeking an answer to. Since I have slammed the Collective down many times as a response to a surprise "throttle chop", and have never become a "lawn dart".

Edited April 13, 2011 by r22butters

[iChris]

Depends on the helicopter.

 

R-22: Slam collective down!

 

Bell 212, 222, 205, etc: push right pedal, hit nrst on GPS, hit enter, then activate. Turn to bearing indicated by GPS, lower collective accordingly to reach airport selected, enter 45 degree downwind, or direct if tower allows. Hover to ramp, set down into wind!

 

Don't try that in the Bell 205. The 205 is the civil version of the UH-1. The Bell 205 is a single-engine helicopter.