"Peter" wrote in message
...

"John R. Copeland" wrote:

Cold avgas should be no problem, assuming no suspended ice crystals.
Take care to keep your fuel clean and dry.
I often fly in the low flight levels where temperatures can be even lower.
The cold-soaked fuel flows just fine, including using a transfer pump to
move wing-locker fuel out into the tip tanks.
I've never had any avgas problems at those temperatures,
but cranking the starter against very cold oil has defeated me too many
times.
Heated hangars are my favorite choice.

This is Europe, where heated hangars are a luxury available to the
chosen few

The specific concern wasn't the stuff flowing into the tank. It is
freezing in the pipework, especially in the injection tubes (IO540-C4
engine, in my case) which are very thin and exposed to the full 150kt
airstream.

There have been various cases of avgas freezing in fuel pipes, and the
pilot having to descend all the way down to god knows where to restart
the engine(s). And it's happened to twins too; one pilot I met
recently had to descend (a Duchess) with a dual engine failure from
25,000ft to 2,000ft over the sea, 100nm away from any coast, before he
could restart. The initial temp was -25C.

I've had the "Twin glider syndrome" in a C-340. South of Klamath Falls,
Or., at FL 220, -30C, The fuel flow for the left one started to twitch, and
whithin 3 minutes, the engine quit. The right one followed about 5 later.
Tops were about 20,000, and the 340 wouldn't stay on top, because I had
picked up a little ice, so after one quit I had to descend. I got the right
one lit at about 8,000, say 2500 agl, and right after breaking out VFR.
After landing in Reno, a quick drain of the tip tanks, showed hundreds of
tiny ice crystals. The sample look like one of those "Snow scenes" that you
shake up and watch the white stuff settle. Yes, I had drained all of the
sumps prior to takeoff. No, I didn't find any liquid water, but it was -2C
in the hangar during preflight. The fuel truck checked out as well. Even
after fueling in Tuscon, warm and dry, I still had "snow" in the sample the
next day. While in Reno, we sprayed a little avgas prist into the tank, and
immediately drained out almost a cup of water. After doing this to all
tanks, the mechanic said I was good to go, and I left, with no more
problems.

Prist = Good

Prist before the engine(s) quit=Better

It does appear that "Pucker factor" on the pilots seat can extend your
glide. I think we are not counting all available sources of lift.

Al G