Special Engineering Services to Establish Inspection Criteria for Bearings to Improve Life Prediction.

Abstract : The CIBLE (Critical Inspection of Bearings for Life Extension) program concept for quantitative nondestructive evaluation of bearing components is briefly reviewed and the automatic inspection equipment used to acquire the data presented in this report is described. Many examples of significant crack networks detected in the races of vendor reworked bearings as well as subsurface flaw indications in a new bearing are illustrated. The savings realized by elimination of the potential for inclusion nucleated failure from the group of CIBLE inspected bearings is estimated, and the future economic benefits of removing potential failures from the J57- 2 and J57- 4 engine bearings currently in the fleet are also projected. The results of endurance testing bearings with service-induced cracks at low stress levels and flaw indications at higher levels are presented and discussed. The results of metallurgical examination of service-induced cracked regions as well as other flaw regions are illustrated, and the results from 1000 balls inspected at the Oklahoma City Air Logistics Center (OCALC) are summarized. A preliminary serviceability criteria for races is outlined and implementation of the criteria is discussed. (Author)