Why helicopters fly by themselves..
I recalled this story when there was a debate in a FW forum about the story of the helicopter that took of by itself and I mentioned that it was fully plausible with a governor equipped heli where the collective lock was off or malfuntioning. It was in a Swedish flying magazine in the early 90's and is sobering reading.
Here was my response in the FW forum:
I might just as an aside mention that the reason the collective/blades go up is due to safety. If the collective pitch rod, horn or nut should fail, you want the blades to default to max alfa/lift. Yes the helicopter will climb at max until it can climb no more (density altitude), but at least it won't crash. And you could in an emergency reduce rpm to get down, perhaps.
There's a harrowing story about this very scenario in the north of Sweden (snow, mountains, forests - think Alaska) some years ago.
The pilot is doing inspection in a small Hughes 300C (two place, and the premier training heli before the R22 came along) and with him is a non-pilot. They're in the mountains. It's freezing. The pitch nut fails and the blades defaults to high alfa and the heli starts to climb. But not very much as the density altitude is pretty high. Now, the pilot has two options: Wait until it runs out of gas and fall like a brick (no autorotaion possible) to certain death, or try to reduce rpm to get down. But due to the density altitude the blades are close to stall already and the cyclic controls are sloppy up high and reducing rotor rpm could risk stalling the rotor completely and make control impossible with no recovery possible.
Now mountains are approaching and they're running out of time. The pilot instructs the passenger (who had some experience riding in heli's) to step out on the skid and try to pull down on the pitch horn manually. On the Hughes 300 you can just about reach the rotor hub if you hang out through the door. It's freezing, slippery and dangerous and he can't do it with a glove. Imagine sticking your fingers up into a rotor hub and try to pull down on a metal horn with your bare fingers in minus 30 degrees! After many failed attempts they manage to be able to somewhat control the height, with the pilot doing finger commands - "UP!", "DOWN!".
They finally managed to land the heli and walked away from it, but I think the passenger froze his fingers off and had to get some removed. True harrowing story.