Eric,

I've had two cases of not being able to open dive brakes
due to low temperatures. One in a Kestrel 19, where
at 19,000 feet on a cold autumn day in Scotland the
over-centre lock became so stiff I couldn't break it
out, the other in a twin Grob due to water inside the
airbrake box freezing and jamming the mechanism.

Never experienced a problem in a considerable amount
of cloud flying above the freezing level in the UK
- I've never heard of the ice on the wings getting
as far back as the airbrake cut-out. If you needed
to open the brakes in iceing conditions (to prevent
overspeeding) I would expect that after a very short
time it would become impossible to close them.

Chris Rollings

In 5000 hours of soaring, I've had the spoilers freeze
shut once. A
brief shower shortly before towing off for what eventually
turned into a
wave flight did the trick. I discovered them frozen
at 4000' AGL while
descending at the end of the flight, but at 3000 AGL,
they unfroze. I
had a tail chute, so a slip would not have been needed,
even in this case.

Has anyone else had spoilers freeze shut without flying
in clouds, were
it seems like you should be expecting it to happen?


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Eric Greenwell
Washington State
USA