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Dear friends.
Today I hade the opportunity to fly with my
brothers Coupe again. They are having an airport festivity over the weekend and
my brother likes these because they waive the landing fees on such occasion.
Otherwise he's paying more than 5 Euros per landing and that
sucks.
So we preflighted the plane. My brother had
just two weeks ago a thoroughly annual inspection done to the plane. It set
him back 600 Euros and the inspector checked EVERYTHING except the rivets on the
main spar. The plane was due for the center section AD and the inspector checked
it with a boroscope.
The only thing he found wrong with the plane was
some looseness at the aileron linkage bolt on the right side. He recommended
changing that bolt at my brothers discretion and that's how I came into
play.
I had the right size new bolts. The ones he ordered
per catalog were the wrong ones.
I have to add that the inspector is a younger
person that insisted on test-flying the Coupe - understandable since he'd
never flown one.
First thing my brother mentioned while
preflighting was that he and the inspector were not able to get one screw
back into place after the inspection, the screw that holds the fairing between
wing and center section at the place under the wing, where the piece that goes
around the leading edge meets the piece aft. I looked at it and decided that at
the beginning of the aft fairing a secure attachment is a must. If the wind gets
under that piece, it'll rip off the rest of it. When my brother told
me that they flew the plane anyway 2 weeks ago, I was filled with skepticism. So
I put the screw where it belongs and felt much better.
Then we did the run-up. I pulled carb heat and
nothing happened. I asked my brother about it and he said that the inspector
noticed a minimal drop in rpm when they test-flew it and that it never was
working remarkable and that we had a dry day today anyway - no need for carb
heat.
Now, having talked lately so much about carb heat
and how important it is, I was briefly thinking on abandoning the takeoff,
but we were under time pressure. An airshow was supposed to start in 45 minutes
and we would surely miss our window of opportunity of taking a flight before the
end of the show that was scheduled for the next 3 hours.
So we took off. The plane did fly marvelous.
Having a climb prop, one could actually use all of the power the C-85 is
able to give, of course overrevving happens faster that way too.
Then I was looking at the time and
recommend a flight back to the airport since the airshow was supposed to start
in 10 minutes. Of course we arrived a few minutes too late and the first
performers did a flyby that took at least ten more minutes. The guys at the
tower told us to "stand by" meaning to wait outside and so we flew at reduced
power circles nearby the airport.
Reduced power - carb heat working marginally if at
all - boy I could smell some trouble here. I pulled carb heat anyway with some
hope and could not see any effect on the engine. Meanwhile I taught my
brother that when carb heat seems not be working one could at least make the
mixture less rich so that the ice does not kill the engine. While I was pulling
the mixture control, the engine would sputter immediately - a sign that it was
in need of the rich mixture and also a sign that we did not accumulate ice so
far - carburetor ice that is.
A few more minutes cruising and we were finally
allowed to land.
We taxied back to the hangar and I had a look at
the carb heat. I let my brother pull the knob and it surely did pull the lever,
but did it move the flap? I looked at the other side of the air box where the
leftover lever from the automatic carbheat control is welded to the flap shaft.
And sure enough, it did not move at all.
The carb heat was shot.
This plane was taken apart and put
together under the supervision of a meticulous mechanic according to
my brother and was just checked by another one like that and as it turns out,
the first one assembled the heat control in a manner so it could not work
and the second one did not see the problem. So what's an annual worth if a
simple thing like that doesn't get caught? The carb heat was assembled in a way
that it would only provide carb heat when the button was pushed in and you would
have to pull the knob to have no carb heat. What did the mechanic think when he
mounted the control that way? Was he testing it? Certainly not.
After a few huh's and what the heck's, the thing
was reassembled and is working as designed now.
(Yes, I know a licensed mechanic should actually do
that kind of work, but the two available to us did not see the problem and were
far away anyway)
What does that tell me? Am I a better mechanic
than these two?
No. I just know what to expect from a plane,
especially from an Ercoupe. Am I a better pilot than my brother ? Not really. He
just did not know what to expect from the carb heat control and that is a drop
of at least 100 rpm when you pull it on run-up. He was just told that it is
"ok" and not to worry.
I don't want to warm up that carb-heat control
discussion again. Carburetor ice happens not that often, but when it happens one
should have a means of fighting it. That's why we pull the knob on run-up
- verifying that it works. If it doesn't or if anything does not work to your
expectation - look after it. Before you take off.
Do I trust mechanics? Yes, to a certain degree. But
one can't trust them blindly. And they know that.
Hartmut, who flew N94804 today
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