Textron Cessna Grand Caravan Ex 208B Pilot's Operating Handbook And Faa Approved Airplane Flight Manual page 644

SECTION 8 CESSNA
AIRPLANE HANDLING, SERVICE MODEL 208B 867 SHP
AND MAINTENANCE GARMIN G1000
CLEANING AND CARE
(Continued)
ENGINE
(Continued)
COMPRESSOR TURBINE BLADE WASH
Pratt & Whitney Canada has developed a procedure for performing a
compressor turbine blade motoring wash. This technique will facilitate
the removal of contaminants from the compressor turbine blade airfoil
surfaces, thereby minimizing sulphidation attack of these surfaces. This
serves as an aid for obtaining optimum blade service life. With this
method, a water or water/methanol solution is injected directly into the
combustion chamber by way of a special spray tube which is installed
in one of the igniter plug ports. This method of engine wash does not
replace the need for a normal engine compressor wash for
performance recovery or desalination purposes.
Compressor turbine blade washing is accomplished using water of
drinking quality (potable) only at ambient temperatures of +2°C (36°F)
and above. Use a water/methanol solution at ambient temperatures
below +2°C (36°F). Refer to 208 Maintenance Manual, Chapter 71-43-
00, Turbine Blade Wash - Maintenance Practices, for approved
washing procedures and the Pratt & Whitney, PT6A-140 Engine
Maintenance Manual, for solution strength according to ambient
temperature.
8-54 U.S.
208BPHCUS-00