Kyle Boatright wrote:

1) Isn't the screw jack "sized" for air loads, with some sort of over
center mechanism to handle the ground loads?

No. The screw jack pushes against a knee-joint mechanism. The "hip" of this joint is
attached to the firewall bulkhead and the "ankle" is attached to the bottom of the
oleo strut. When the gear is full up, the joint is bent up into the housing and the
screw mechanism is fairly short. When the gear is down, the knee-joint is straight,
and the screw mechanism extended. The screw mechanism is also attached to the
bulkhead in such a manner that it is horizontal when the gear is up.

What I'm getting at is if someone flipped the wrong switch, could that
explain the collapse of both mains, and explain why there are apparently
broken screw jacks on both mains?

I doubt it. If someone raised the gear on the ground, the plane would just settle on
the wheels. Keep in mind that this mechanism was designed to handle at least 4 tons
more than this particular aircraft weighed at the time of the incident. On the other
hand, these things are ancient, so it might be possible.

George Patterson
If you don't tell lies, you never have to remember what you said.