Coyote Ugly wrote:

GumpAir wrote:I'd never admit to it, as it was far too stupid to ever say I did it, but I remember some flights out of BRW and OTZ at 60 below. Both at sea level. Calculate that DA.....

Gump

Ha.... Holy s#!t ... -9179'

Wonder how many inches of MP you were pullin..?

I didn't use anywhere near full power for takeoff. And I guarantee you, I didn't use a power off approach to land either...

Problem with that level of cold is popped nosewheel tires. I got real good at wheelies in the C207, and could take off and land, then taxi to parking with the nosewheel (flat) never touching the ground till I was in my parking spot.

Gump

Whats the dangers, can ya blow a jug at those DA's?

Lots of problems with cold below minus 40 degrees F.

Way easy to overboost. Mixture gets way too lean (way I remember it, is you push rich as you descend) but the knob only goes in so far, and I think the accurate DA it those conditions is actually about 4,000 feet below sea level . In a carbureted engine you gotta pull on carb heat to raise the DA by warming the air. Shock cooling is real, MP and RPM stay in cruise down to short final. And, rubber and plastic just explode.

Nosewheels are most at risk. They like to pop off the rim as you make the turn from the runway to the ramp. There's no flex in the tire or tube and the turn puts a load on the sidewall. Make the turn, and flat they go. You either wheelie to get home, or you're stuck in some shithole native village for a few days until you can get a company mechanic out to change the tire for you.

And heaven help you if you crash and get hurt at those temps. You break an arm and you're gonna die. 20 below is a non-event. 50, 60 below and you'd better be scared. Luckily those temps are actually rare on the Arctic coast, but we still flew when it got that cold. Just very, very carefully.

Gump

GumpAir wrote:
Way easy to overboost. Mixture gets way too lean (way I remember it, is you push rich as you descend) but the knob only goes in so far,



Gump

At -9000 ft I may not get any RPM, or at least not for long. the Commander has manual waste gates. At home I get 42 inches at about half throttle.
At sea level its a little above 1/4 throttle on a warm day
What would one do at -9000ft if your boost goes to red-line at a very narrow throttle plate opening? I suspect the valves would look like tulips in short order, no way to get enough fuel into it to keep it cool.
Book calls for full rich at any altitude above 34 inches, until above 18,000ft I don't think the lever will go far enough forward for -9000ft

Glad it don't get that cold in Nevada. It was only -20F at the airport last night here in Austin. And irregardless of what Gump says, that was cold.