Hi Mike,
I'm delighted that your fix was so easily found & accomplished --
congratulations! And thanks for posting the story; I would like to
be able to better follow your description of the affected parts. For
the sake of a tech-beginner learning what terms like "inlet manifold
flange" mean, could you either post a photo or a drawing or even
refer to part ## in the blow-ups of the parts catalog? Thank you -
Linda
9a. G-HARY sorted
Posted by: "Mike Willis" [email protected] aircoupe_mike
Date: Mon Jul 5, 2010 10:15 am ((PDT))
Hi everyone,
The same day Linda ended up in a field in the US, I had to make a
Œprecautionary¹ landing in the UK due to severe loss of power and
rough
running. This happened about 30 minutes into a flight in my Alon A2.
I had decided to climb from 2,000 to 2,500 feet, applied full power
and my
sweet running engine suddenly ran very roughly. After finding that
application of carb. heat made the situation much worse, and not
seeing any
other immediate problem I looked for somewhere to land. I could just
hold
altitude at 70 mph and by luck there was a nearby farm strip on which I
successfully landed. On throttling back in the flare the engine
stopped.
After pushing the aircraft off the strip I tried cranking with the
mags off
to check the engine was free, and we heard a sticking or hissing noise.
Hand turning the prop seemed to indicate the compressions were fine
and we
could see nothing leaking, dripping or broken.
Today I went to the farm strip with my engineer. He found the
problem in
around one minute (the time it took to open the left cowling plus 10
seconds) and another minute to repair.
There is an induction pipe - a metal tube - connecting the
carburettor to
each cylinder inlet. The inlet manifold flange on the cylinder is
larger
than the pipe, so there is a short rubber sleeve slipped over the
pipe to
match the diameter and then a longer and larger diameter rubber sleeve
fitting over both to form the seal. These are held in place with two
hose
clips.
The lower of the hose clips on the rear port cylinder induction pipe was
loose and the rubber spacer that side had slipped down the pipe.
This meant
that there was no mixture to that cylinder  it was sucking air - and it
would also imbalance the mixture to the other cylinders. This
accounted for
the sudden power loss and rough running.
Therefore the various theories such as carb. icing, stuck inlet valve
and
cracked piston were all wrong, and a precautionary landing was
definitely
required. The engineer did a thorough inspection and ground check of
the
engine, and then I flew it away.
So check those hose clips for tightness once in a while, and may it
never
happen to you!
Best regards,
Mike
[email protected]
www.ercoupe.co.uk
Alon A2 Aircoupe
A-188
G-HARY
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