Abstract:
The Department of the Navy has been developing and deploying Health and Usage Monitoring Systems (HUMS) for more than 20 years. One of the many uses of HUMS is as an enabling technology for implementing Condition Based Maintenance (CBM), the goal of which is to improve aircraft safety, affordability, and availability through an as-needed (rather than scheduled) approach to maintenance. To drive the fleet toward a more realized implementation of CBM, a CBM event detection and reporting system was developed for the Navy's fleet of H-60 aircraft, accompanied by updated policy requiring the fleet to adhere to the guidance within these CBM reports. For this investigation, five years of maintenance and readiness data from two naval H-60 aircraft types were studied to identify trends related to this platform's implementation of CBM. This five year period includes two years of data from before the CBM reports and policy were introduced, one year of data during which the technology and policy were being implemented, and two years of data from after the reports and policy were in effect. The metrics chosen to evaluate changes in fleet behavior were Mission Capable Rate (MC Rate), Non-Mission Capable Rate due to Unscheduled Maintenance (NMCMU Rate), Unscheduled Maintenance Man-Hours per Flight Hour (UMMF), Scheduled Maintenance Man-Hours per Flight Hour (SMMF), and Functional Check Flight Hours per Flight Hour (FCF Rate). Overall, the fleet mean MC Rate decreased, NMCMU Rate, UMMF, and SMMF increased, and FCF Rate was unchanged in the period after the reports and policy were introduced. However, for most of these metrics, a squadron-level analysis showed that the individual squadrons did not trend uniformly in the direction of these fleet averages. In a continued effort to characterize the fleet response to the implementation of CBM, it is recommended that further investigation into additional metrics and analysis techniques be pursued.