Failure investigation of blade and disk in first stage compressor

A matched blade tenon and disk mortise of the first stage compressor in an aeroengine fractured simultaneously, Apparently, both had fatigue features on the fracture surfaces. Macro observations showed the cracking sites were roughly at the central region of the matched tenon and mortise. Contact surfaces examination revealed there were important marks, showing abnormal contact of the tenon and mortise in service. Material qualities were inspected and the stresses in the tenon and in the mortise were calculated under normal conditions. These demonstrate that the failures were not due to the insufficiency of failure resistance but the deviation from expected conditions. Conclusively, the bad contact of the tenon and the mortise is responsible for the failures. Field non-destructive inspection was performed on other aeroengines of the same type, and some cracks, which were very similar to those in the fractured tenon and mortise, were found. Further investigation revealed that the design shortcoming resulted in over-compensation of centrifugal bend moment and bad contact condition. (C) 2000 Elsevier Science Ltd. All rights reserved.