A Survey of Propulsion Systems Malfunctions-Failures Resulting in Helicopter Mishaps

A survey of propulsion system material malfunctions/failures (M/F) that resulted in helicopter mishaps was conducted. This survey is based upon the experience of four Army helicopter models during the period January 1971 to June 1978. The propulsion system M/F causing mishap experience is analyzed with respect to its power plant, power transmission, lubrication, fuel, and instrumentation subsystems. In assessing the power plant subsystem M/F experience, components of the lubrication system, fuel control, gas generator section, and accessory drive are analyzed. For the power train subsystem, the main transmission, tail rotor gearbox, intermediate/ combiner gearbox, and drive shafting are assessed for their M/F rate. The lubrication, instrumentation, and fuel subsystems are similarly treated. For each major subsystem, components are further analyzed. For example, main transmission M/F experience is evaluated considering such components as the lubrication system, filter, plumbing, oil cooler, and chip detector. Component M/F histories relating to helicopter mishap causes are presented on the premise that designers and manufacturers of propulsion system components who are familiar with past system malfunctions/failures will produce more reliable propulsion system components for future helicopters.