Failure analysis of high pressure fuel pump on piston aircraft engine

High Pressure Pump (HPP) failure leads to a sudden fuel cut off, during the training flight. To investigate the root cause of HPP failure, two more aged fuel pump (TSN 600h), from the same flight academy, was received. The failed pump and aged pumps were disassembled and analyzed by optical microscope (OM), scanning electron microscope (SEM) and metallographic analysis. Results showed that the metallographic technology of the three pumps were the same. Foreign debris found in the failed fuel pump stuck one plunger. At next revolution the rotor was pushing hard against the follower plate causing a sheared plunger and cylinder. Subsequent fragments leads to the other two plungers' failure. Due to more and more debris, other parts of the pump fail as a secondary failure. Friction or stuck marks in the failed pump and the other two aged pumps indicated that it is more likely to have axial scratches in operation base Z. This operation base is close to desert.