Filter Debris Analysis by Energy Dispersive X-ray Fluorescence Applied to J52p408 Engines

A technique to analyze particulates extracted from inline jet engine oil filters using energy dispersive X-ray fluorescence (EDXRF) is presented. This technique, developed by the U.S. Department of Defense’s Joint Oil Analysis Technical Support Center (JOAP-TSC), is termed filter debris analysis (FDA). Six beta prototype instruments capable of performing FDA-EDXRF in an automated mode were manufactured under a U.S. Air Force (USAF) Productivity Reliability Availability and Maintainability (PRAM) project. J52P408 (J52) engines were suffering from what appeared to be sudden, catastrophic failures resulting in the loss of aircraft. The root cause of the failure was a lack of lubrication in the 4 1⁄2 bearing area that caused the 4 1⁄2 bearing cage to fracture. The analysis of oil samples by rotrode emission spectroscopy did not indicate a catastrophic bearing failure mode was evolving. FDA-EDXRF was one of the techniques employed to try to discover the onset of 4 1⁄2 bearing failure. An FDA-EDXRF profile of the J52 engine was developed in about 3 weeks. Initially, particulates obtained from J52 filters where FDA indicated that abnormal amounts of bearing wear were present in the engine were sent to Pratt & Whitney Aerospace Laboratory to be analyzed by scanning electron microscopy (SEM). The SEM results confirmed the presence of M-50 alloy or bearing wear. Subsequent teardowns of a portion of the engines having abnormal bearing wear indicated by FDA had fractured 4 1⁄2 bearing cages. This paper will outline how FDA technology has kept the J52 fleet flying.