Minor spark plug fouling can usually be cleared as foliows:
(1) Magnetos
-
Both On.
(2) Throttle
-
2200 RPM.
(3)
Mixture
-
Move toward idle cutoff until RPM peaks and hold for ten seconds.
Return mixture to full rich.
(4)
Magnetos Recheck.
If engine is not operating within specified limits, it should be inspected and repaired prior to
continued operational service.
Avoid prolonged single magneto operation to preclude fouling of the spark plugs.
B.
Check throttle and propeller operation.
Move propeller governor control toward
low RPM position and observe tachometer. Engine
speed should decrease to minimum governing speed (200-300 RPM drop). Return governor
control to high speed position. Repeat this procedure two or three times to circulate warm
oil into the propeller hub.
Where applicable move propeller control to "Feather" position. Observe for 300 RPM drop
below minimum governing RPM, then return control to "Full Increase" RPM position.
CAUTION.
.
.
Do not operate the engine at a speed in excess
of
2000
RPM
longer than
necessary to test operation and observe engine instruments. Proper engine cooling depends
upon forward speed of the aircraft. Discontinue testing
if
temperature or pressure lintits are
approached.
1. Instrument indications.
A.
Oil Pressure:
The
oil pressure relief valve will maintain pressure within the specified
limits if the oil temperature is within the specified limits and
if
the engine is not excessively
worn or dirty. Fluctuating or low pressure may be due to dirt in the oil pressure relief valve
or congealed oil in the system. This should be corrected prior to continued operation of the
engine.
B.
Oil Temperatures: The oil cooler and oil temperature control valve will maintain oil
temperature within the specified range unless the cooler oil
passages or air channels are
blocked, leading to rapid wear of moving parts in the engine.
C.
Cylinder Head Temperature: Any temperature in excess of the specified limit may cause
cylinder or piston damage.
Proper cooling of cylinders depends on cylinder baffles being
properly positioned on the cylinder heads and barrels, and other joints in the pressure
compartment being tight to force air between the cylinder fins.
Proper cooling also depends
on operating practices.
Fuel and air mixture ratio will affect cylinder temperature.
Exces-
sively lean mixture causes overheating even when the cooling system is in good condition.
High power and low air speed, or any slow speed flight operation, may cause overheating by
reducing the cooling air flow. The engine depends on the ram air Row developed by the
forward motion of the aircraft for proper cooling.
To Next Page
Loading...
Need help?
General
