IO-240 Series Engine Installation & Operation Manual
4-3
31 October 2011
Engine Operation
according to instructions in Section 4-2.3.2.1; see Section 4-2.3.2.2 for engine models
with an altitude compensating fuel pump.
4-2.3.1. Engine Break-In
WARNING
Avoid long descents at high engine RPM to prevent undesirable
engine cooling. If outside air temperature is extremely cold, it
may be desirable to increase drag to maintain engine power
without gaining excess airspeed. Do not permit cylinder head
temperature to drop below 300°F (149°C).
CAUTION: High power ground operation resulting in cylinder and
oil temperatures exceeding normal operating limits can be
detrimental to cylinders, pistons, valves, and rings.
1. Start the engine according to “Engine Start” instructions in Section 4-3.2.
2. Conduct a normal ground run-up and take-off according to the AFM/POH
instructions.
3. Monitor the following engine instrument panel indications: a) engine RPM, b) fuel
flow and pressure, c) Oil pressure and temperature, d) cylinder head temperature, and
e) exhaust gas temperature to verify the engine is operating within the parameters
specified in Section 2-3.
4. Reduce the engine speed to climb power according to the AFM/POH instructions.
Maintain a shallow climb attitude to achieve optimum airspeed and cooling airflow.
5. At cruise altitude:
a. Maintain level flight cruise at 75% power with best power or richer mixture for
the first hour of operation.
NOTE: Best power mixture setting is 100°-150°F (38°-66°C) rich of peak
exhaust gas temperature. Adjust engine controls or aircraft attitude to
maintain engine instrumentation within specification.
b. For the second and subsequent hours of flight, alternate cruise power settings
between 65% and 75% power with appropriate best power mixture settings.
WARNING
Long descents at high engine RPM or low manifold pressure
may cause undesirable engine cooling. If outside air
temperature is extremely cold, it may be desirable to increase
drag to maintain engine power without gaining excess airspeed.
Do not permit cylinder head temperature to drop below 300° F
(149° C).
6. Descend at low cruise power settings. Avoid long descents or descents at cruise
power RPM with manifold pressure below 18 in. Hg. If necessary, reduce engine
RPM to the lower limit of the specified operating range to maintain sufficient
Summary of Contents for IO-240-A
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