Lycoming Carb Heat

Gents,

Though this is not strictly an IFR question, I am pretty sure that you have
opinions that I would like to get.

Subject is Lycoming O-360 engines. I have flown behind a number of them in
Pipers and the POH instruction on carb heat is always "as required."
Specifically there is no requirement for carb heat on the landing checklist.
This makes sense to me as the intake charge is routed through the oil pan cum
intake manifold and, with the throttle nearly closed hence low flow velocity,
should get adequately warmed up. At least that is my rationale for why the POH
does not call for heat.

I am about to get checked out in a Civil Air Patrol 172 that has an STC'd O-360
installed in place of the original Lycoming O-320. The 172 POH wants carb heat
on approach. This makes no sense to me. If I have to do a go around it is just
one more workload item/one more thing to forget and, from my Piper experience,
it does not appear to be necessary. My guess, without benefit of any actual
facts, is that this POH requirement comes from Cessna's Continental roots and
has no engineering justification. So it seems wise to ignore it.

Comments? (Please, let's not go to the FARS with this question. That is not my
interest.)