In-Line Oil Debris Monitor (ODM) for Helicopter Gearbox Condition Assessment

Abstract : The development of an inline, full flow oil debris sensor system for the engine nose gearbox of a military helicopter is described. The sensor is designed as a direct one for one replacement of an existing magnetic chip detector, located in the scavenge oil line of the gearbox. The sensor is based on an inductive measurement technique which enables the system to detect, count and classify wear metal particles by size and type (ferromagnetic or non-ferromagnetic) with a detection efficiency of close to 100% above the minimum particle size threshold of approximately 175 microns. The design requirements, principle of operation, mechanical design features and electronic design features of the sensor are discussed. The performance and characteristics of the sensor system, as measured during development testing, are also presented.