Section X ENGINE TESTING (Continued)
1-93 GENERAL (Cont)
Do not mix oil of different military
specifications of synthetic oil may
incompatible with each other. Should
both types of oil become mixed, drain
and flush oil system (Section VIII,
Paragraph 1-71) and refill with oil.
Lubricating Oil (E.2) or (E.71).
5. The following test information is relevant:
General. The performance of a turbine engine
conditions. For this reason, it is absolutely essential that
accurate barometric pressure (not corrected to seal
level) and ambient temperature are obtained for the
immediate area at the time of engine trimming and
performance checks be carried out at low wind velocity
with the engine intake facing into wind. Even this
precaution will not prevent an unstable trim at moderate-
to-high wind velocities.
Precipitation. Performance and trim checks
should not be attempted during moderate to heavy
precipitation or fog.
Water entering the engine inlet changes the power
output of the engine, the change being proportional to
the amount of water ingested. Any form of moisture in
the air causes the engine to ingest water. This includes
the occasions when water or snow is blown into the air
inlet by the propeller or sucked in by the compressor.
Freezing rain or slushy snow has exactly the same
effect on power output as water ingestion, and in
addition may cling to inlet ducts or the inlet screen and
upset the flow of air to the engine.
Fuel. All trims must be made using the normal
Engine Fuel (E.19) used in servicing.
Ground Operating Limits. The limits shown in
tables 1.9.1 and 1.9.2 are provided as a guide and are
based on sea level pressure and temperatures as specif
Engine Overtemperature. Overtemperature
conditions are usually preceded by an excessively rapid
rise in fuel flow, compressor speed, and/or interturbine
overtemperatures affect engine service life just as
seriously as a single prolonged lower overtemperature
condition. The higher the temperature, the sooner
serious engine damage occurs and the more extensive
is the inspection required. When an
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