Cessna 208B - Page 483

CESSNA SECTION 8
MODEL 2088 (675 SHP)HANDLING, SERVICE, AND MAINTENANCE
ENGINE CARE (Continued)
ENGINE COMPRESSOR WASH
The benefits of performance improvements and increased service life
of hot section parts accruing from instituting a regular compressor wash
program cannot be overemphasized. A compressor wash ring is
installed on the top of the engine adjacent to the induction air inlet
screen to facilitate this maintenance program.
Compressor washes can be performed by either motoring the engine
with the starter or running the engine. Depending on the nature of the
operating environment and the type of deposits in the engine gas path,
either of the two wash methods can be used to remove salt or dirt and
other baked on deposits which accumulate over a period of time and
cause engine performance deterioration. When the wash is performed
solely to remove salt deposits, it is known as a "desalination" wash. A
wash performed to remove baked on deposits to improve engine
performance is known as a "performance recovery" wash. A motoring
wash is conducted at a gas generator RPM of 14-25%; the running
wash is carried out at an
N,of approximately 60% (23,000 RPM). The
water or cleaning mixture and rinsing solution, dependent on ambient
temperature, is injected at different pressure, depending on the wash
method being conducted.
Operating environment determines the nature of the wash, the
frequency, and wash method recommended. If operating in a
continuously salt laden environment, a desalination wash is
recommended following the last flight of the day by means of the
motoring method. Occasionally salt laden environments may
necessitate a desalination wash each week using the motoring method.
Less severe and more general operating environments are not as
conducive to rapid deposit buildup but eventually can contribute to
performance deterioration and necessitate a performance recovery
wash at intervals of 100-200 hours. In these general environments, a
motoring wash is recommended for light soil and multiple motoring or a
running wash is suggested for heavy soil.
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U.S. 8-49