This chapter discusses the key findings of an investigation into the failure of an aircraft engine fuel pump. It explains how investigators came to the conclusion that metal slivers from a heavily worn spring may have interrupted the flow of lubricant to one of the slipper pads, causing adhesive wear and the welding of slipper pad material onto the surface of a mating cam plate. Excessive friction between the slipper pads and cam plate, in turn, created a torsional overload that caused the camshaft to break. The chapter presents SEM images showing the wear pattern on one of the springs along with photographs of the damaged slipper pads and cam plate. It also includes an image of a copper flake found in one of the pistons and discusses the results of qualitative x-ray chemical analysis.

An aircraft fuel pump failed just after takeoff, resulting in engine flameout. Investigators discovered that one of the seven pistons broke into several pieces, causing the quill shaft to fracture. An examination of the fracture surfaces revealed severe rubbing on the quill shaft and beach marks on the piston along with a nick on the opposite side of the barrel. In addition, the metal around the corresponding hole in the rotor had plastically deformed and the slipper pad was gone. Based on the investigation, the failure most likely occurred due to a problem with the spring guides or a jammed slipper pad. The chapter provides several recommendations to avoid such failures in the future.