My Engine Fire!!

(Account of overpriming and resulting engine fire deleted)

Any of the carburettor mounted below engine Lyc and Continental
engines are prone to this...

I had it happen to me in a 182. The 182 is particularly prone
if the engine starts normally, and you taxi the
aircraft a short distance (say to the fuel island), shut off
the engine, leave it off for a few min, and then restart...

What happens is that the metal induction tubes are still cold
soaked; the short run not being sufficient to heat them. Fuel
evaporates normally in the carb during the engine run, but because
of the induction tubes are cold, the fuel droplets condense
on the cold metal surface, like moisture condenses on a cold
beer glass.

As long as the engine is running, there is sufficient flow
up the induction system to suck the fuel into the cylinders.
If you shut off the engine, the condensed fuel runs back down
through the carburettor, and puddles in the carb air box.
A backfire during the next restart attempt is all it takes
to set the puddle of gas alight.

The admonition in the manual for continuing to crank in an
attempt to suck the fire up into the induction is there for
a reason. Be especially wary of an induction fire on the
second restart if the previous engine run was just a few
min...

MikeM
Skylane '1MM