MAYDAY in the Everglades

David Lesher wrote:

I was going to ask about that. A lean engine runs hotter than a rich
one. But that's mostly EGT, and I'm not sure it will work back
enough to alter the carb temp. What say you folks?

On the Maule I had, the carb heat comes from a muff on one of the exhaust pipes,
so higher EGTs should produce more heat.

George Patterson
There's plenty of room for all of God's creatures. Right next to the
mashed potatoes.

On 4-May-2005, Scott D. wrote:

The longer you wait to do this, the cooler the engine is
getting and carb heat becomes less effective.


I agree that applying carb heat quickly after experiencing power loss is
critical, but not because the ENGINE cools rapidly -- it doesn't. The heat
for carb heat comes from he exhaust system, which does cool rapidly if the
engine is producing little or no power.

--
-Elliott Drucker

On Thu, 05 May 2005 05:59:42 GMT, wrote:

On 4-May-2005, Scott D. wrote:

The longer you wait to do this, the cooler the engine is
getting and carb heat becomes less effective.


I agree that applying carb heat quickly after experiencing power loss is
critical, but not because the ENGINE cools rapidly -- it doesn't. The heat
for carb heat comes from he exhaust system, which does cool rapidly if the
engine is producing little or no power.

Your right. My whole point was that you are no longer producing heat
thus things start cooling down. Yes, I know that carb heat comes from
a shroud that is around the exhaust. I didnt think that I had to get
technical here. But I guess for some I have to.

Scott D

To email remove spamcatcher's

wrote:

snip

I've had instances of mag failure where switching to one improved the
situation quite a bit. One was a bad timing gear that did include the
backfiring, but another was a shorting distributer block that made the
engine extremely rough and caused a power loss. In that case, I
switched to the good mag and had a much less worriesome ride home.

I guess I don't completely understand your (or Marty's) reluctance to
at least check the mags in flight. Even at best glide, the engine is
not going to come to a stop because you grounded a mag. If it gets
worse, you just switch back, then try the other one. At some point,
you decide which combo (left, right, or both) works best and you leave
it there.

Maybe there is something I haven't considered. If so, I would
welcome enlightenment.

John Galban=====N4BQ (PA28-180)


Years ago I was flying a C-150 and it started running real rough. I did
an airborne mag check and found it ran better on one mag. I flew the
remainder of the trip (about 40 minutes) that way and reported this to
the FBO. Can't remember now what the problem was.
--
Regards, Ross
C-172F 180HP

On 5-May-2005, Scott D. wrote:

I agree that applying carb heat quickly after experiencing power loss is
critical, but not because the ENGINE cools rapidly -- it doesn't. The
heat
for carb heat comes from he exhaust system, which does cool rapidly if
the
engine is producing little or no power.

Your right. My whole point was that you are no longer producing heat
thus things start cooling down. Yes, I know that carb heat comes from
a shroud that is around the exhaust. I didnt think that I had to get
technical here. But I guess for some I have to.


I'm not trying to be picky. On the other hand, I think it's just a good
idea that if we intend to share knowledge on this newsgroup that we be as
accurate as possible. Of course YOU know it's really the exhaust system
that provides the heat, but some less experienced pilots or pilot wannabes
may not. From a safety standpoint, this is not a trivial point.

--
-Elliott Drucker

On Thu, 05 May 2005 18:14:30 GMT, wrote:


On 5-May-2005, Scott D. wrote:

I agree that applying carb heat quickly after experiencing power loss is
critical, but not because the ENGINE cools rapidly -- it doesn't. The
heat
for carb heat comes from he exhaust system, which does cool rapidly if
the
engine is producing little or no power.

Your right. My whole point was that you are no longer producing heat
thus things start cooling down. Yes, I know that carb heat comes from
a shroud that is around the exhaust. I didnt think that I had to get
technical here. But I guess for some I have to.


I'm not trying to be picky. On the other hand, I think it's just a good
idea that if we intend to share knowledge on this newsgroup that we be as
accurate as possible. Of course YOU know it's really the exhaust system
that provides the heat, but some less experienced pilots or pilot wannabes
may not. From a safety standpoint, this is not a trivial point.


Point taken

Scott D

To email remove spamcatcher's

I've had real bad carb ice two times in a C-150 on perfectly clear
days. Both times the conditions were similar to yours. One time at
6500 feet; one time at 8500; about 70 degrees on the ground and about
42-44 at my cruising level each time, and also in the south. I got
detailed weather information from Shaw AFB WX after I got back each
time which showed relative humidity at my cruising altitude was just
over fifty percent on both occasions, despite the beautiful clear skies
and great visibility. This is when carb ice sneaks up on you and hits
you hard, leaving you shocked and in disbelief, trying other solutions
and cursing your mechanic.

One time the carb heat cured the situation very quickly, the other it
took quite a while and I had to keep adjusting mixture. When you have
carb ice the mixture changes as the ice builds up and again as it melts
away which sometimes has you "chasing" the engine with throttle and
mixture manipulations to keep it running.

I didn't read all the other posts and it may have been mentioned
already but it's important to get full throttle in right away when
dealing with carb ice also.

In 3000 hrs flying mostly small piston planes I've learned to
immediately pull carb heat full out and leave it out at any burble,
hesitation, slow down or silence! Once you've got the carb heat
engaged, go to full throttle if you haven't already and adjust mixture
for best power -- you may have to keep adjusting the mixture several
times as the shape of your venturi/level of blockage changes from ice
melting or, (GASP) growing because your carb heat is inop or
insufficient.

- Brett Justus, ATP, G/S MEI/CFII, ASC