"Tman" x@x wrote in message
. ..
Flying a lot of 152s and 172s with carb heat lately. When inbound, I've
been taught to pull the carb heat "on" downwind, hey actually use it as a
power control to slow the plane just a bit mid-field, and then more
importantly, just leave the thing on till clear of the runway and cleaning
up. No matter what the temp, humidity. And to have it on at all times
when the RPM is less than the green band. Kind of a preventative.

A few times I have been coming in on short final and needed a burst of
power due to a sudden downdraft, or needed to pour on a little juice cause
my approach was coming up just a bit short. Moving the throttle forward
1/4 to 1/2 inch, i.e. giving it a little juice but certainly not a go
around type of thing, often times I would get a stumble, hicuup, drop in
RPM'S for 2-3 seconds before the horses responded.

Lot of convective turb lately and that power really comes in handy at
times on mid to short final. Kind of a shocker when the engine doesn't
respond quite nicely.

This has happened on a few birds, especially on hot days. I think what's
happening is the engine is just too rich, hey I've got the mixture all the
way in, it's hot (air less dense), and it's (way) hotter with the carb
heat on ( air much less dense), all enriching the mixture, and when I put
on a little power the accelerator pump in the carb over-enriches the
engine for just a little bit; causing the stumble.

Other pilots and the A&P just tell me to pour on the power a little
slower.

I think I'm going to follow a new SOP. Turn the carb heat off on
mid-final. Reasoning: no carb, esp a warm one is going to ice up in 30
seconds, sets me up better for a go-around, and will prevent this stumble
business (I did test it out at altitude, and it prevents or at least
seriously mitigates the stumble).

thoughts?
T

Shouldn't be a problem, but sometimes it happens.

Apply power a little slower.
or
Carry just a tiny bit of power on final. Sounds like you might be
approaching at cut off.
or
Bump a little power every 15 to 20 seconds to keep the engine clear.


Personally I wouldn't cut the carb heat.