Raimo
it probably was ice. When the airplane is cold soaked at hi altitude as
soon as you descend into warmer air the water vapour in the air will
condense on the airframe and of course freeze.
That is my guess. It used to happen to gliders high in wave over
Scotland. I remember looking out at the wings and seeing frost forming
and outlining the spar and ribs.
Graham
Raimo Toivio wrote:
>
> All
>
> I visited couple of days ago QNH altitude 16200 feet
> (it was flight level 150). Even the last 1000 feet took
> only 4 minutes to climb. My engine is a free aspirated
> Rotax 912S. My purpose was to find a max usable
> ceiling service. Europa would have gone happily higher
> but that altitude was enough for me personally. Temp
> was around 15 degrees below freezing but climate in
> the cocpit was still comfortable.
>
> When I started to descend, I got immeadiately a stall
> warning. I have an Europa factory stall warning kit with
> audio-visual warnings. System was activated during
> whole descending and even in the hangar one hour
> after landing. Next day it was OK again.
>
> What was that? Is there any other explanation than
> ice formation in the pipe from the wing leading edge
> to the pressure probe?
>
> I did not feel good when listening half an hour a buzzer
> and watching big blue high bright led which tried to tell
> me I am stalling...I was not brave enough to switch that
> uncorrect warning off.
>
> Regards, Raimo
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--
Graham Singleton
Tel: +441629820187
Mob: +447739582005
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