"Dan Luke" wrote in message
...

"Bob Gardner" wrote:

I can't find anything in the discussion of carb ice in The Lycoming Flyer
to make me think that full throttle somehow obviates carb ice when
conditions are conducive to icing. If ice is forming on the interior of
the venturi, the position of the throttle plate won't make much
difference. Lycoming does say that ice is more likely at low power
settings, but I think we all know that.

Apparently I'm guilty of believing what I was told by instructors without
checking the facts. Carbs can ice any time ambient conditions are right
for it. My tiedown neighbor with a Skylane tells me I'd have figured this
out a long time ago if I had a TCM O-470 182.

--


That is because iced carbs will have the motor *stop* at idle settings
simply because the venturi is "choked", while they may continue to run quite
well at cruise settings with the venturi open. So they kept telling us to
carb heat at low power and eventually we started to believe we only *needed*
carb heat at low power because nobody told us different.

I finally found an instructor in the latter stages of my training who set me
straight on a number of things, including that one.

....and he was the one who emphasized the need to use a "cruise checklist"
every 15 minutes at least, which would be approximately like:

HI to compass heading
oil temps and pressures
fuel gauges; fuel switch correct tank as necessary
rpm/MP; pull carb head momentarily and check drop
tweak power; tweak mixture