Failure analysis of landing gears strut bearings

Abstract

This paper analyses TB 20 training aircraft main landing gear attachment bearings which were failed as a result of cracks. Strut bearing is an attachment fitting of landing gear which attached to the wing spar and secures the hinged strut. TB 20 Trinidad aircrafts are used for training purposes at Anadolu University. With respect to Service Bulletin, the hinged strut attachment bearings should be inspected for crack detection after reaching 6000 landings or 4000 flight h, whichever occurs first (SB 10-080-57 Amendment 4, 1994). Cracks on the bearings were detected during the nondestructive inspection. The crack initiation and propagation on the attachment bearings were investigated by using light microscope and scanning electron microscope (SEM) attached with an energy dispersive X-ray spectrometer (EDX). The results of light microscope and SEM showed that the cracks were initiated by corrosion and assisted by fatigue and the crack propagation was accelerated by corrosion.