wrote:

Yeah, I'm curious too. I have an old Speed Astir, and had some trouble
with the flap lock becoming disengaged. It usually happened turning
base to final, and went from full positive to full negative in blink
of an eye. There is considerable force at all airspeeds and conditions
(except a negative "G" push) exerted on the flap control toward the
negative flap setting.

finally someone imaginative... There is a pressure difference betweene the
upper and the bottom surface of the wing, thanks to whitch our gliders can
fly (if there is enyone who doesn't know that...). If one of your ailerons
pins out, or your flaps aren't locked at their position - they will all
deploy up. It is impossible that the flaps are balanced that much, to
overcome the pressure difference and deploy to positive - especially in a
glider weighting 185 kg.

Mat