IO-240 Series Engine Installation & Operation Manual
4-17
31 October 2011
Engine Operation
4-3.11. Engine Shutdown
Supplement the AFM/POH engine shutdown procedures with the following:
1. Boost Pump ....................................................... OFF
2. Throttle.............................................................. 1700 RPM
WARNING
Absence of RPM drop during the magneto check may be an
indication of a faulty ignition circuit resulting in a condition
known as “Hot Magneto.” Should the propeller be turned by
hand, the engine may inadvertently start and cause personal
injury or death. This condition must be corrected prior to
continued aircraft operation.
CAUTION: When operating on single ignition, some RPM drop
should be noted. Normal indications are up to 150 RPM drop and
slight engine roughness as each magneto is switched off. RPM drop
in excess of 150 RPM may indicate a faulty magneto or fouled spark
plugs. Avoid prolonged single magneto operation to preclude spark
plug fouling.
NOTE: If the engine runs roughly after single magneto operation,
increase engine speed to 2200 RPM in the BOTH position and lean the
mixture control until the RPM peaks for ten seconds before returning to
the full rich position to clear the spark plugs and restore smooth operation
before returning to single magneto operation.
The difference between magnetos individual operation should not exceed
50 RPM. Maximum RPM drop for either magneto is 150 RPM. Observe
engine smoothness during magneto switching.
3. Ignition Switch .................................................. R
RESULT: 25-75 RPM drop (not to exceed 150 RPM) and slight engine roughness.
Maximum allowable RPM drop spread between magneto channels is 50 RPM.
4. Ignition Switch .................................................. BOTH
RESULT: Engine speed returns to normal. Allow Ignition switch to remain in BOTH
for approximately 30 seconds to clear engine.
5. Ignition Switch .................................................. L
RESULT: 25-75 RPM drop (not to exceed 150 RPM) and slight engine roughness.
Maximum allowable RPM drop spread between magneto channels is 50 RPM.
6. Throttle.............................................................. IDLE
7. Mixture Control................................................. IDLE CUTOFF
8. Ignition Switch .................................................. OFF
Summary of Contents for IO-240-A
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