In article 1126723296.783817@sj-nntpcache-3, Dave Butler wrote:
Mitty wrote:

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.

Your Piper experience differs from mine. Facing a long slow ILS through wet
clouds in a Piper, I'd set full carb heat, a minute or two before reducing
power. Ever taxi off the runway and have your engine quit?

I have had it quit on short final (in a PA-28-181). Almost exactly
the situation you described -- ILS on a cool day with very small
temp/dp spread, low vis, low scattered layer. Over the airport
boundary, I pulled the throttle back to idle to land and things got
quiet. I was on the ground almost before I had a chance to realize
what went wrong. Hung out for a while on the runway while the ice
melted then started up and taxied off. Had a mechanic look at it, he
found no problems, so we assumed carb ice.

From that day on, I used carb heat in Pipers on instrument approaches.

I've also gotten carb ice in an Archer at cruise power in clouds.