Title from cover

"NPS-OR-97-017."

"September 1997."

AD A331 598

Includes bibliographical references (p. 19)

Health and Usage Monitoring Systems are receiving a great deal of interest, in an attempt to increase the safety and operational readiness of helicopters, and to minimize maintenance costs. These systems monitor (and can record) various flight parameters, pilot conversations, engine exhaust debris, metallic chip detector levels in the lubrication system, rotor track and balance, as well as vibration levels at selected locations throughout the airframe and the power drive system. Vibration levels are currently being observed on two operational SH-60B helicopters and on an H-60 power drive system installed in the Helicopter Transmission Test Facility (HTTF) at the Naval Air Warfare Center, Trenton, NJ. This paper employs classification trees to analyse vibration signatures produced in the HTTF, identifying those characteristics which distinguish normal signatures from signatures produced by known faulted parts. These trees are quite successful in separating the two types of signatures and achieve small misclassification rates for HTTF data. They are also applied to vibration data collected from an operational aircraft; assuming the tail gearbox in the operational aircraft has no faults, the trees derived from the HTTF produce a high proportion of false alarms

aq/aq cc:9116 11/28/97

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