Monday, March 12, 2018

Helicopters and Autorotation

The recent helicopter accident in NY got me asking "Why didn't he auto rotate down?" I know it works because I experienced it first hand.

I was returning from offshore one afternoon. I was the only passenger. In order to pass the time, I started talking to pilot about my growing apprehension about flying in helicopters. He went on with the many reasons that helicopter pilots will tell you why they are safer than fixed wing aircraft. One of these was the ability to auto rotate and land safely. "Let me show you.", he said. He then twisted the throttle back to idle and dropped the collective to the deck. We started falling like a rock and my stomach was left somewhere 100 feet above me. He then began pulling pitch and slowed us down to a more reasonable fall rate. To my relief, he then brought the power back on and we flew back to base without further demonstrations. He claimed that he could land the helicopter under auto rotation and then go into a low hover and rotate it 180 degrees before setting it down again. Furthermore, he had to practice auto rotation on a regular basis.

So, auto rotation is real and the pilot should have been able to land softly on the water. I will await the NTSB report with interest.

Of course, when I was flying offshore, our pilots were all Viet Nam veterans and those guys could do some very delicate things with a Bell 212 or a Bell 206 Long Ranger.

Next time, I'll tell you about translational lift and it's application departing an offshore platform on a hot day in a fully loaded helicopter.


JayNola said...

There's a couple components that can fail and completely preclude autorotation including the gear box seizing, the tail rotor taking a walk, and the the bkades folding up. In which case you're strapped into a brick.

mostly cajun said...

The Viet Nam-era pilots are all retired now. The two assigned pilots for my company are in their twenties.

As a fixed-wing pilot, as long as you don't severely bend or lose pieces, airplanes can glide. Of course, they'll be moving at considerable speed when ground or water shows up in the equation, but that's just life.

As your previous commenter stated, several parts of the helicopter flight mechanism must stay patent for a successful autorotation.

Peripatetic Engineer said...

Jay - True, but reports are that they are looking the accidental closing of a fuel shut off valve.

Cajun - A helicopter can be defined as 10,000 unrelated parts, all bent on self destruction, flying in relatively close formation.

Old NFO said...

Having ridden through two real ones, they 'can' get exciting. Looking at the video, he did make a soft landing. The issue was the rollover and rapid sinking. If you've never been through the helo dunker, the odds of survival are slim, because of the disorientation!

The Old Man said...

BTDT - RVN 69-71. Autorotated into 2 hot LZs. Also later (1984?) got to fly with some wobblies-then-flying-as-civilians who LOVED to practice autos to watch the non-vets lose their shit. USUALLY autorotations would work out.
JayNola has it right - when Murphy wants your keister, he gets it whether you want to give it up or not....