An analysis of the integrated mechanical diagnostics health and usage management system on rotor track and balance

Abstract

This thesis is concerned with the operational benefit of the Integrated Mechanical Diagnostics Health and Usage Management Systems (IMD HUMS) rotor track and balance (RTB) functionality. The questions addressed are whether there is a savings in flight hours expended on functional check flights (FCF's) when compared to present practices, if there will there be a reduction in directed maintenance man-hours (DMMH) spent on maintenance related to the rotor system, and the impact on Operational Availability. Experiments were conducted using a discrete event simulation model of squadron flight operations and organizational level maintenance. The simulation is generic and can be used in the analysis of other helicopters. Input parameters governing the distributions of maintenance action inter-arrival times were estimated from Naval Aviation Logistics Data Analysis (NALDA) databases and squadron experiences on such systems. The analysis suggests that flight hours spent in FCF are dependent upon vibration growth rate, an unknown quantity, and the maintenance policy for rotor smoothing. Directed maintenance man-hours decrease with increasing numbers of IMD HUMS configured aircraft and further gains are achieved with a maintenance policy suited to a continuous monitoring system.