R44 Engine Failure and Auto-Rotation

touch-n-go

Well-Known Member
Looks like he handled the engine failure pretty well given the time and place of the engine failure. Not a heli guy myself but found this interesting...

 

deadstick

Well-Known Member

You can see the manifold pressure go to ambient and the engine RPM go to 0 (LH needle of dual tach above MP gauge in the lower right).
 

USMCmech

Well-Known Member
Very well done by the pilot. He had to turn away from the powerlines by the road and put it down between some brush. In prefect hindsight he could have killed his forward momentum some more, but I don't know anyone who could do much better.

Power loss in a helicopter is a good and bad situation. On one hand you can't glide very far at all, on the other hand you don't need a large area.
 

MikeD

Administrator
Staff member
Not bad at all, good and survivable. Agreed that he could’ve leveled the bird out and flared some more before touchdown in order to touchdown in a little less of a forward slide just as extra insurance. With skids, a slide on landing works fine in asphalt/concrete, not so much off-field due to the potential for the skids digging in and either cartwheeling forward onto the back/side, or the rapid deceleration causing the main rotor blades to flex downward and strike the tailboom or the top of the cockpit.

Glide wise, it’s somewhat relative in a helo. Some do better than others. An R22 or Hughes 500, the area you’re going to auto to in somewhere near your feet angle-wise, and you’ll be fighting to preserve rotor RPM. In a UH-1 Huey, the area you’re going to auto to is somewhere out your front windscreen, and you’ll be constantly checking the bird as it tries to rapidly increase its rotor RPM.
 
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deadstick

Well-Known Member
Very well done by the pilot. He had to turn away from the powerlines by the road and put it down between some brush. In prefect hindsight he could have killed his forward momentum some more, but I don't know anyone who could do much better.
I replayed this several times. Although we can’t see the rotor tach or the annunciators because of all the gadgets, the horn came on pretty quickly. That means the Nr dropped below 97%. You can tell he was adjusting the collective because it went on/off a couple of times before it stayed on. There is an option to drag the Nr down to no less than 90% in order to stretch the glide range. However, that cyclic flare is needed to build the RPM back up to give the blades enough energy for the decel and touchdown. If the pilot is too aggressive on the flare, the blades can strike the boom, but since directional control wasn’t lost, I’m guessing it was severed during the sudden stop of the touchdown.
 

touch-n-go

Well-Known Member
Saw this discussed on another forum but it looks like the mags were in the off position at takeoff. You can see this at 0:17 in video. Also, the pilot's reaction after crash at about 2:03 where he sighs "Aah... it's all right.." after touching the mag switch and maybe realizing that the switch is off. He has a strange aha kind of grin on his face. Interesting.
 
Saw this discussed on another forum but it looks like the mags were in the off position at takeoff. You can see this at 0:17 in video. Also, the pilot's reaction after crash at about 2:03 where he sighs "Aah... it's all right.." after touching the mag switch and maybe realizing that the switch is off. He has a strange aha kind of grin on his face. Interesting.
The engine won’t start or run with the mags off. Unless this is something different in a helicopter?
 

ZeroPapaGolf

Well-Known Member
The engine won’t start or run with the mags off. Unless this is something different in a helicopter?
It would with a broken P-lead. You could imagine someone choosing to defer repairing that since there’s no prop starting danger like an airplane. Not legally of course, but it’s a plausible justification.
 

Minuteman

“Dongola”
An intermittent P-lead connection with mags off might even be a reason for the engine to stop choo-chooin' along.
 

Space Monkey

a law for the rich and another for the poor member
Looks like he handled the engine failure pretty well given the time and place of the engine failure. Not a heli guy myself but found this interesting...

That engine didn't sound right from the get go. But...that looked pretty damned well executed.

Successful auto-rotation in a Robinson proceeds in accordance with the steps of the following proof:
miracle.jpg
 
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MikeD

Administrator
Staff member
That engine didn't sound right from the get go. But...that looked pretty damned well executed.

Successful auto-rotation in a Robinson proceeds in accordance with the steps of the following proof:

The Robbie actually autorotates in a pretty docile manner, the R44/66 better than the 22 albeit. Its low inertia rotor system is offset by its extreme light weight. So long as the pilot does his part correctly, the bird has a good glide ratio and won’t bite you.
 
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