Failure analysis of a helicopter main gearbox lube pump

A seized lube pump of a helicopter was investigated. Examination revealed that the pump got seized due to seizure at the 2nd stage rotor and centering plate interface. Evidences suggest that the seizure was caused due to adhesive wear resulting from the debris generated in-situ. It has been established that constant rubbing of the 2nd stage rotor key with the centering plate was responsible for the generation of debris. Factors such as improper lubrication or entrapment of foreign particles as the causes of failure have been ruled out. Analysis showed that with the present design of the rotor keys, such seizure in the lube pump is unavoidable. It is recommended that the rotor keys be redesigned so that the contacts between the keys and the centering plate are avoided. A detailed analysis of the failure is presented in this report