Aircaft: Europa Tri Gear
Engine: Rotax 912 UL
Propeller: Airmaster 322
Help! I would welcome any advice or suggestions regarding a problem which is
afflicting
my aircraft. It has developed a strange vibration/resonance which occurs
after establishing the cruise. For example, after a normal take off and climb
I set the prop to Cruise, reduce the MFP to 26 which gives approx. 100Kts
at an indicated 5200 RPM. Everything appears normal at this stage. If I increase
the cruise setting to 27, or greater, everything remains smooth, but reducing
back to 26 re-introduces the vibration (which is noticeable unless the throttle
is reduced almost to idle), which although it does not shake the aircraft
to pieces, is most noticeable. The vibration remains through reduced throttle
settings and can only be cleared temporarily by adjusting prop pitch to use
a higher RPM and power settings.
Initially I was convinced it was a propeller issue, but detailed checks have so
far failed to highlight any problem. Airmaster are convinced it is not their
propeller at fault but gave me several thing to check, all of which I have done.
Europa suggested the prop carbon brushes and tracking should be cleaned which
I have done. For a while I thought this might have cleared the fault, but it
returned after 55 mins of flight. Interestingly At the same time as I had
cleaned
the tracking I had removed the whole exhaust system for inspection. I could
not find anything wrong, no holes, or loose pipes so I refitted it and lock
wired everything.
I have inspected the carburettors, replaced the rubber mountings and balanced
the
system and everything appears to be normal.
I have to admit I am at a loss to know what to check next. It may be related to
something that was removed and refitted during the exhaust inspection, but I
cannot find anything obvious and I do not understand why the problem is not
apparent
as soon as cruise power is applied.
I would welcome any thoughts on this matter as it is driving me mad!
--------
Gordon Grant
G-BWFH
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