Oil Debris Monitoring for Helicopter Drivetrain Condition Based Maintenance

An advanced damage detection technology has been developed that is capable of identifying and tracking the degree of damage to bearing and gear elements of engines and transmissions through on-line monitoring of metallic particles introduced into the oil system as a result of damage. This on-line, full flow oil debris sensing technology has the potential to be a reliable Condition Based Maintenance (CBM) indicator for the early detection of drive system component damage and, thus enhance the capabilities of existing helicopter Health and Usage Monitoring Systems (HUMS). The technology is already successfully applied to various aircraft and industrial applications. This paper reviews the common surface fatigue failure characterististics of bearing and gear rolling elements and the application of oil debris monitoring as an effective CBM method of early damage detection. It describes the advanced on-line oil debris sensor technology, its inductive principle of operation, and application to the condition monitoring of lubrication wetted systems of engines and transmissions. It presents both experimental and operational results that characterize bearing and gear failures in terms of debris quantity, particle size distribution, rate of debris generation, and how these data are used to provide an early indication of damage and set operational limits on damage severity.