Failure Analysis of Ball Shedding of Aircraft Body Spherical Bearings

In order to investigate the problem of bearing ball shedding in the rocker arm centering ball bearing of the flat tail load mechanism on the aircraft, bearing ball shedding in the rocker arm centering ball bearing was tested and analyzed from the aspects of bearing quality, accidental load damage, technical requirements, etc., to determine the cause of the failure of the centering ball bearing. The results indicate that the width of the double fork ear groove at the tail of the load mechanism was designed too large, and the rotation range of the outer cylinder of the flat tail load mechanism was not limited enough, resulting in the swivelling angle of the spherical ball bearing exceeding the allowable range, which are the main failure causes. Through adding a washer between the outer plane of the single ear of the rocker arm and the inner plane of the double ears at the rear end of the flat tail load mechanism to constrain the swivelling angle, the using effect was improved. Supplementary analysis of common cases further confirms the importance of the actual alignment angle of self-aligning bearings being within the allowable alignment angle range during application. This study has practical significance for guiding aircraft structural design and standardizing installation and maintenance operating procedures.