(Steve Chalfin) wrote in message . com...
"Happy Dog" wrote in message ...
Many GA a/c are restricted to operations above a certain temperature. In my
case (Zlin 242L) the restriction is -20C at sea level and goes down to -40 C
(or F) at 9000 feet. But, the POH doesn't say why. Anybody know?


A recent thread on the Diamond Owners Website addressed the -20 degree
C limitation for the Diamond Star. According to Diamond, this is due
to temperature limitations on the avionics.

Think about density altitude. At -20 C and sea level, the density alt
is just under -10000 feet according to the my trust E6B. At -40 C and
9000 feet pressure alt, the density alt is -10000 feet.

Looks like a limitation on the range of adjustment that can be made.

In the AIM, there's also a limitation on adjustment for your
altimeters due to low pressure. If you can't adjust your altimeter
correctly, you can't fly. I think this happens in Alaska very
occasionally.

-Malcolm Teas