Rotax 912/914 Gurus,
I've been building a Europa for most of my leisure time for the past
seven years. Now I seem to be falling at the final hurdle.
A few years ago, I bought a 914 with seven hours on the clock. The
engine is now fitted to the aircraft and has passed all its tests (fuel
flows, fuel pressure, oil pressure, operating temps). We are still
ground running / testing. The carbs are mechanically and pneumatically
balanced and the engine starts easily (every time).
We have run the engine through the full throttle range, up to 5700 RPM.
However, sometimes when we advance the throttle, the engine cuts.
Sometimes this happens before we reach the 100% gate, sometimes we get
past the gate and it cuts when we push it to 115%. At all times, there
is a noticeable "flat spot" as we accelerate the engine up from about
2000 RPM to 3500/4000 RPM.
Another troubling aspect of the engine's operation is that when the
engine is started with choke (from cold) it cuts when the choke is
released, no matter how much warming it has had. The engine can then be
readily restarted without choke, whereupon it will run sweetly - bar the
behaviour described above...
The fuel filters are clean and it will run happily at 4000+ RPM when it
gets there. It does not appear to be fuel pumps, both pumps give very
healthy flow rates, (when tested with the fuel pressure regulator
pressurised to 5.1 -5.8 PSI (per the Europa manual)).
I have to admit to having reached the limits of my mechanical
competence. In an ideal world I would contact the local expert, who
would apply their wisdom, however, I live in the wilds of Scotland
(Aberdeen), and Rotax 914 gurus are thin on the ground up here (to the
best of my knowledge).
So, before I have to resort to importing a Rotax guru from
England-shire, I wonder if any of you technical wizards on this forum
has come across similar behaviour on a 914 (or a 912, because I don't
think it is turbo related) and could shed some light on my darkness.?
With thanks and regards,
Dave
Dave Moore
XS Monowheel #550
Aberdeen, UK
Tel: Day: 01224 267815. Home: 01224 572041
|