Hi Glenn,
I had what might be a similar experience a few years ago with our 912S powered
XS, which I believe was caused by vapor lock. At about 9,000 feet altitude I
shut down the engine to do some glide tests, and when I restarted a few minutes
later the engine ran rough. When I turned on the boost pump, the engine quit.
I believe that the extra flow created when the boost pump went on forced a
'vapor bubble' into the carbs and killed the engine. It restarted moments later
and I made a precautionary landing to check things out. We had noticed rough
running on a few other occasions, and came to a few conclusions.
1) This seemed to happen following a start with the engine already hot.
2) It only seemed to happen in the winter when auto fuel has more volatiles in
it.
3) It was more likely (but not always) to happen at higher elevation, where the
vapor pressure is lower.
We assumed the problem was vapor lock caused by the close proximity of the
exhaust
to the carbs and associated lines.
We fitted aluminized heat shield material to the bottoms of the carbs and the
associated
fuel lines and have not had the problem since.
Regards,
Terry Seaver
A135 / N135TD
Monowheel XS with 912S
-----Original Message-----
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com] On Behalf Of Glenn Rainey
Sent: Monday, May 09, 2011 3:24 AM
Subject: Europa-List: 912 quit
07/05/2011 we experienced an engine stop with the 912 in our monowheel - this
happened just as the throttle was being advanced at the commencement of the
takeoff
sequence, so we rolled only a hundred feet or so and coasted to a halt.
After less than a minute, a first restart attempt was successful, and we taxied
back to the apron uneventfully, tail between legs, where my second action was
to put on the kettle for a cup of tea.
Perhaps relevent, I had heard a sharp 'bump' about 10 seconds earlier, as we
were
turning on the threshold to line up, and thought I had hit a light or something
with the outrigger, but nothing was seen. The ambient conditions were about
21C and some showers were in the area with a convective active frontal system;
we had just completed 1 circuit to land after a reasonably expeditious
departure,
but on backtracking from the first landing, had to hold for about 5-6
minutes on the main apron, then backtrack the second half of the active.
Immediately after parking first action was to pull the top (XS) cowl when we
noticed
fuel boiling up the vent tubes which run into the airbox, both sides.
My take on this is fuel vaporisation due to high carb temps. Our (second owner)
europa is NOT fitted with drip trays under the carbs - now an item of concern,
nor is there any exhaust manifold insulation. The more I read the greater my
concern about in-cowl temps and comprehensive action to prevent a repeat of this
experience.
Fuel pressure indications were normal, and coolant temp was showing about 40C,
although we now suspect the Temp sender is malfunctioning. Oil and CHTs where
nominal.
Ours may be just another data point, but while we trawl this archive and worry
the problem, any comments would be most welcome. My own last engine quit, also
on the ground, was due carb ice in an O-200; but this was much more 'exciting'
coming as it did at the moment of truth .. "G-HL, rolling" - phut!
The climb-out to our east is lacking a good escape option.
Glenn Rainey
Cumbernauld, Scotland
G-OJHL
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