Protect Heat Exchangers
Heat exchangers must be protected while other services are being performed on the aircraft. Intercoolers, oil coolers, air conditioner condensers, and the radiators on liquid-cooled engines are all subject to becoming clogged with dirt, dust, paint, paint overspray, paint stripper residue and dry paint stripper beads. Heat exchanger fins are very small and closely spaced. When they become clogged, heat exchanger performance can be severely impaired. The result is overheating of the air, oil, or coolant involved. The further consequence is loss of a component, an engine, or aircraft performance. Sustained abuse can result in permanent damage to all equipment involved.
To ensure efficient heat exchanger operation:
During Stripping and Painting: The heat exchangers must be masked during paint stripping and painting operations. Caution: If paint or paint overspray gets on a heat exchanger, it may be impractical to remove the paint thus requiring replacement of the heat exchanger.
Inspection: At each 100 hour inspection (or more often if there is cause to suspect contamination) visually inspect air passages of heat exchangers for trash, dust, dirt, bird nests, and other debris.
Dust Removal: To remove dust and dirt, wash heat exchangers with hot soapy water and rinse with hot water.
Annual Inspection: At annual inspection, flush the radiator air passages with MEK. Flush the oil cooler and intercooler air passages with hot soapy water followed by a hot water rinse. Note: Solvents other than MEK may leave a film residue which will collect dust and further clog the heat exchanger fins.