----[Please read http://ercoupers.com/disclaimer.htm before following any advice in this forum.]----
Donald,
After reading your
description below, I’m very inclined to think that you did NOT have carb ice. It sounds like something is making your
engine run too lean since carb heat also richens the mixture some. I find it hard to think you’d get carb
ice so quickly after takeoff on three occasions.
Since carb heat enrichened
the mixture and made it run somewhat better, I’d say you might have been
running a bit into the detonation range and are susceptible to detonation
caused engine failure (and may have some damage already).
It sound kind of like the
time I had an air passage in my Stromberg carb get clogged by air-filter fibers
causing excessive leanness and roughness/partial loss of power (improved by
carb heat).
You might be suspicious
of the competence of the A&P for his failure to consider mixture
issues. Perhaps you want to find a
different A&P.
Since the engine was
still running and the carb heat didn’t melt the “ice” to give you full power, I
don’t think you had carb ice (on three occasions).
Personally, I’d have the
carb pulled off and gone through (but I’m mostly ignorant on mechanical/engine
stuff). I’d check everything
related to engine mixture control.
I’ve only got a pilot’s
viewpoint on this stuff – I’m no kind of mechanic. These are my best guesses.
Here’s a thought before
your next test flight: A leading
national ultralight engine overhauler said: If you have an engine stoppage or
power loss in the air, and you land, it’s really smart to be SURE you know what
caused the problem before you take off again.
Ed
Burkhead
http://edburkhead.com/
ed -at- edburkheadQQQ.com (change -at- and remove the QQQ)
-----Original Message-----
From: Donald Perricone
[mailto:[EMAIL PROTECTED]
Sent: Thursday, October 21, 2004
11:09 AM
To: Ed Burkhead
Subject: Ercoupe carb icing
Ed:
There have been several e-mails from
members about carb icing and I want to add a situation that happened to me in
our coupe N93334 about a week ago. The airplane is pretty much a standard
415C with a Cont. 75 upgraded to a 85, It is equipped with a
Marvel carb which was rebuilt last Fall when the plane was restored
to flying condition. We also have the STC for auto fuel and use a
50% 87 oct. 50% Av 100 low led.
On the particular day I flew the
temperature was in the low 80 F. and about 75% humidity. Pretty normal
for this time of the year in Central New York. In preparation
for the flight I did the usual pre-flight inspection which of course
includes draining a sample of the fuel out of both wing tanks and the header
tank. I didn't find any water and everything was clear. The
"before take-off check" list was normal with no excessive mag.
drop and the carb heat check was normal. The take-off was on a grass
strip of 2,500 feet at 800' MSL with little or no wind.
Everything was good with no problems. I flew over to another airport
which is about 20 miles away and landed on a hard surface runway with no
problems. I shut down the engine and went in to have a coke. When I
came out I started the engine and taxied out to the run-up area and performed
the regular pre-flight check with no problems. The take-off was normal
until I got to about 300'AGL and the engine started to lose power. It was
too late to abort the take-off so I immediately turned on the cross wind leg
and headed downwind for the same runway I had just left. I flew the
downwind at about 600'AGL and pulled the carb heat on. The engine still
wasn't running at full power but it was enough to keep me in the
air. I flew a short base and final and landed.
After this interesting experience I
taxied back to the run-up area and did another pre-take off check. The
mag drop was normal and the carb heat was also normal. I also
did full power static run-up and got the usual 2,350 RPM. I now went
to the very end of the runway and started my take-off run. The full power
came up as normal but when I started to climb the power again started to
sag. I at once pull the power and aborted the take-off.
At this point I said, "enough is enough" and called a friend of mine
to bring some tie-down rope and come and get me.
I related all of the above to our A&P
who was working at the airport and he said he would go over with
me to look at the plane and see what was wrong. We did
that and he drained fuel out of all three tanks and found nothing.
He also pulled the filter on the carb and found nothing. He pulled
the screen on the gasculator and disconnected the line from the header tank
and the fuel was flowing properly. He even elevated the nose
about 45% on a concrete block with plane tied down and had me run
it up to full power and found nothing. After he got
everything buttoned up he told me to try another take-off and the same
thing happed. At this point he didn't have any answers but to suggest
that I take-off with half carb heat. I did this and everything was
o.k. When I pulled the carb heat off the RPM went up about 200
RPM. The A&P conclusion was the culprit was carb ice. We have
flown the plane about 3 hours since then and everything seems to be o.k.
The A&P wants to put a shield around the carb air intake because it doesn't
fit well with the nose bowl to keep the air from cooling the carb
housing. Other than that maybe this particular carb is prone to
icing.
Any thoughts about the above situation
would be appreciated.
Thanks!
Don 93334
============================================================================== To leave this forum go to: http://ercoupers.com/lists.htm Search the archives on http://escribe.com/aviation/coupers-tech/
