Hi Folks,
Firstly an apology to all those good souls who made the DOTH to
Andrewsfield today, that I didn't.
The reason I didn't was that my engine decided to misbehave on
takeoff. Run-up was normal and I got my normal max RPM on power
application, but after approx 50m the RPM dropped to 5400. I
abandoned T/O suspecting the prop controller - 5400 is the Airmaster
climb power setting. However having exercised the controller, I did
another power run and the engine was definitely unhappy. It was very
rough above 4000 RPM and couldn't reach the normal max and the EGT
reading was right up. Trying the separate ignition circuits certainly
made it run rougher, but neither side much worse than the other.
I taxied back suspecting a plug lead off - I've had that before- but
on removing the cowlings all leads were in place. I then took out all
the plugs, they looked pristine and all identical. I took off the
carb bowls and gascolator - absolutely no sign of anything other than
clean, clear fuel.
I put it all back together and it ran perfectly, giving max RPM with
stable fuel flow and moderate EGT for a good 2 mins.
I decided to bite the bullet and do a couple of short flights, again
no problems.
One thing that springs to mind is fuel vaporization, but it was the
first flight of the day and not particularly warm. I am using mogas
and the aircraft had been fully fueled but left in a covered hangar -
recent daytime temperatures up to 24 deg C, nighttime probably no
lower than 15. However I have done approx 750 hrs, many times in much
higher temperatures, (though it has to be said that the highest
temperatures would have been on the continent using Avgas), and I
have never had this problem before. The aircraft was standing out in
full sun on a warm day before my 2 short flights, but here was no
hint of a reoccurrence.
Has anyone had anything similar, or got any suggestions?
All the best, Paddy
Paddy Clarke
Europa XS - 404 G-KIMM
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