TM    55-2840-241-23 CHAPTER  7 CLEANING,   INSPECTION   AND   REPAIR Section   I.   CLEANING 7-1. General. Use care in separating metals for cleaning. Observe the following general cleaning precautions. Petroleum solvent vapors are toxic. Provide adequate ventilation for personnel using it. a. Petroleum solvent (item 3, table 2-2) is the clean- ing  solvent recommended for nonferrous parts (clean” ers for steel will damage nonferrous parts.) Do not use rust preventives on magnesium  and  aluminum  parts. b. Clean aluminum-coated steel parts with carbon re- moval compound (item 17, table 2-2). Rinse the part with water and dry with an air blast. c. Clean steel parts with cresol base cleaning com- pound (item 18, table 2-2). Rinse the part thoroughly with hot water. Coat parts with a compound of one part rust preventive (item 19. table 2-2) and the parts oil (item 20, table 2-2). 7-2. Cleaning Engine Exterior Surfaces Flush  or  spray  wash  external  surfaces  with  petroleum solvent (item 3A, table 2-2) to remove grease. oil. and dirt. Ensure that all openings are plugged or covered be- fore cleaning. Engine  thermocouples  should  never  be  satu- rated or sprayed with cleaning solvents Liq- uid cleaning solvents will penetrate the po- rous magnesium oxide insulation. Engine heat will vaporize the solvents leaving a resi- due containing carbon which causes a low resistance to ground. 7-3. Compressor Cleaning to Restore Lost Performance. Allow the engine to cool for a minimum of 45 minutes prior to spraying the compressor. Mandatory cooling period is required to prevent warpage to internal engine compo- nents. Buildup of dirt in the compressor can result in a seri- ous loss of engine power and performance.  Lost  perfor- mance may be restored by flushing the installed engine with a water/solvent solution as follows: Methanol is flammable; it should not be used if the ambient temperature is above 4°C (40°F), its vapor is harmful; it could be fatal or cause blindness if swallowed. Keep it away from open flame and avoid pro- longed breathing of the vapor. NOTE Once the cleaning procedure is started, it must be carried through to completion without delay.  At  ambient  temperatures  below  4“  C (40°F) and above -29°C (-20°F), use a 40 per- cent Methanol (item 34. table 2-2),60 percent water mixture, in place of fresh water. The temperature of the wash solution should not be below 4°C (40°F), ideally it should be be- tween 21-26°CC (70-80°F). T O avoid spray- ing concentrated Methanol. which is combus- tible. mix the solution thoroughly. NOTE B&B 3100 (MIL-C-85704, Type I) is the pri- mary cleaner for Army turbine engines and re- mains  an  approved  cleaner  for  locales  where environmental restrictions permit. Engine cleaners that conform to MIL-C-85704. Type II and Type IIA are also acceptable engine cleaners and meet EPA environmental require- ments. Continue use of B & B 3100 where not restricted. Where restrictions apply use MIL-C-85704. Type II and Type IIA cleaners. Approved Type II and Type IIA cleaners shall be  used  in  accordamce  with  the  existing  wash- ing procedure. Type IIA cleaners do not require dilution with water. Both types of cleaners are less effectzive than Type I cleaners. Therefore more frequent engine washes may be required to achieve satisfactory results. Change 17 7-1