What was found
ON MAINTENANCE POST-FLIGHT, DISCOVERED RIGHT ENGINE HYDRAULIC MAIN FILTER WET WITH HYDRAULIC FLUID. INVESTIGATION SHOWED LEAKAGE FROM FILTER BOWL SEAL AND TEFLON CHEVRON AREA. INSPECTION OF O-RING SEAL AND BACK-UP TEFLON RINGS SHOWED BEVEL DEFECT ON BACK-UP RING LETTING O-RING DEFORM. THE BACK-UP RING SHOWED BEVELS CUT THE SAME ANGLE PREVENTING OVERLAP FROM A SMOOTH SURFACE. REPLACED O-RING AND BACK-UP RINGS THAT CORRECTED THE CONDITION. SUBMITTER RECOMMENDED TECHNICIAN'S ATTENTION TO BACK-UP RING INSPECTION. AT TIME OF INSTALLATION, PLACE ON FLAT SURFACE AND SEE HOW ENDS OVERLAP FOR A MATCHED SMOOTH SURFACE.