Attended a seminar on Rotax 9 series engines where Phil Lockwood spoke. He
had several interesting observations on the care and feeding of these engines
which I had not seen elsewhere. Many of his ideas came from observations made
on the Katana fleet in the US and may or may not apply to the Europa.
When changing the oil, always use 2 wrenches to open the drain on the bottom
of the tank. The bottom of the tank may collapse if excess torque is applied
with a single wrench. Always remove the top of the oil tank, the screen, and
the bottom plate when changing the oil; then clean out any sludge in the
bottom of the tank, where it tends to accumulate.
Be careful when replacing the tank top to route the oil lines as they were
originally, avoiding sharp bends. The suction side oil lines are prone to
collapse where sharp bends are used. Increased oil temperatures occur with
partial collapse - be alert for a temperature rise of 20 to 40 degrees over
temperatures observed previously under the same operating conditions.
Complete line collapse causes engine failure, of course. Oil lines soften
with heat and tend to collapse at higher temperatures rather than when oil is
cold.
Sludge formation is worsened by synthetic oil combined with leaded fuel. He
recommends 15/50 mineral oil when using 100LL combined with oil changes at 50
hours. Oil changes at 100 hour intervals are recommended only when using
synthetic oil and unleaded auto gas. Use of TCP with 100LL seems to reduce
sludge formation.
Recommends changing spark plugs at 200 to 300 hours.
The gear box is subject to wear under certain conditions which can often be
avoided in practice. Gearbox wear is accellerated by long periods of
idling, when slight engine roughness causes the gears and damper mechanism to
chatter. He suggests setting the idle relatively high to minimize chatter:
1800 to 2000 rpm, i.e. prop 600-800rpm. A vacuum balancer helps set the idle
for maximum smoothness, again minimizing gear wear. Plan ahead so that after
startup there is minimal idling time before takeoff. The transmission
should be removed and re-shimmed (apparently bellville (?) springs in the
vibration dampner need replacing periodically) about every 400 hours - takes
about an hour after the transmission is removed. If the above
recommendations are followed he says that the transmission will last at least
as long as the engine.
The Rotax 912/914 engines are designed to run at high rpm and show less wear
when operated at higher rather than lower rpm's. He recommended minimum
cruise rpm of 5300 and said that Katana's operated at full throttle, 5500,
showed less wear than those run at lower rpm - operation at 4800 caused
increased wear compared to 5300. Sludge formation was also observed to be
less with engines run on 100LL at 5500 vs lower rpm.
Overall, an interesting seminar. Quite a lot of info in an hour.
Regards, John A044
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