Saturday, January 12, 2008

So, I almost killed Kristy...

Flight #: 029
CFI: Kristie H.
Aircraft: Robinson R22 Beta II
Aircraft ID: N8361N
Duration: 1.3hrs
Cumulative Time: 31.9hrs

Well, not really. But if it were not for her quick reaction, we certainly would have a few bruises. Here is what happened... we were doing straight-in autorotations along side of hover autos.

A straight in autorotation is set up 700ft MSL (500AGL) and 70 KIAS. When level, lower collective, right pedal, slight aft, and completely roll off throttle, then pitch pull to get your rotor RPM into the green. Then you continue your entrance to land safely. It is an advanced maneuver to get you safely to the ground without power. Really a beautiful thing when it is done right... you just sort of float in.

A hover autorotation is set up at about 1-2 ft AGL hover. When ready, you completly roll off throttle, hard right pedal, little right cyclic and pause... then hard and large pitch pull on collective. This is quite a bit more abrupt and is used when the engine cuts out in a hover. You have very little time to execute this... cause you are only 1-2 ft off the ground. Dropping a helicopter from 2 feet does not sound like much but 1400lbs can make a pretty big dent. That and you have a blender blade spinning above your head.

After about 4 hover autos in a row I got mixed up... and, I have to be honest here, hover autos freak me out a bit. I know practice makes perfect... and that fear and panic will eventually go away but not this day.

In short, I set up for the hover auto, rolled off throttle, lowered collective and threw in right pedal. The helicopter just dropped out of the sky. Kristie tore up the collective to reduce the fall but we hit hard... and bounced up about 8 inches and then slammed down again. An absolute mess. Where did I go wrong? I lowered collective. You never lower collective in a hover autorotation... never. You only lower in a straight-in or 180 auto rotation. I just got confused.

See, when you lower collective, you reduce the pitch of the main rotor blades... and lose lift. If you lower throttle you reduce the power to the blades... and you lose lift. If you do both and don't have airspeed and altitude... you got nothing left. And, in a hover auto you have neither airspeed nor altitude. So, you are in a helicopter, in the air, with nothing. That's why we fell.

When you do it right, you pause a little, then yank the hell out of the collective to soften your hit. If you do it perfectly, you just land with a little bump. But, that pitch pull slows down the rotors significantly... so you can only do it once. You have to wait till you need it at the last minute.

So, I suppose there is a silver lining here... I know how bad a 2ft fall can be and I will never do it again.

Other than that end-of-the-day mess, the rest of the day was good.

2 comments:

Anonymous said...

Hovering autos suck...

They gave me fits as a student, and they still give me fits, even though they're much easier in an R44.

The name is a misnomer. It's not an auto at all! I don't know any CFI's who would not like to have the so-called hovering auto removed from the PTS. It serves no real purpose.

When I did my PP-RH checkride, I think my instructor must have told the DPE that this maneuver gave me fits. After the oral when we were getting ready to go out to the ramp, he told me "The only thing I look for in a hovering auto is that you keep the helicopter straight".

OK, pal. You only need to tell me that once! When it came time to do the maneuver, I just worried about keeping the helo straight and not about cushioning the landing. Without any comment, he then had me go on to the next maneuver...

Anonymous said...

I think it's a right of passage to almost kill your instructor (total tongue in cheek).
I tried to kill mine just last weekend!
Apparently I was alot more bothered by stress than I thought I was. I didn't have any clue I was not fit to fly. Anyway, he throttle chopped me, and I barely got the collective down. We were in a nose dive and about 82% rotor rpm's. Oops. Isn't that about where the blade "tulip" up and we fall? I believe so. You and Kristy were what, 2 feet above the ground? Try 2000 feet out in WPA!!! AAARRGGGHHH!! I'm still upset about it.
I guess we all have a bad flight.
I have enjoyed your blog. See yah around dispatch, eh? Tee hee hee