Maintenance, Engineering, and Operational Decision-Making Metrics Derived from Simple Maintenance and Aircraft Datasets

Using in-service maintenance data, it is possible to predict and forecast the propulsion system contribution to aircraft and fleet level unavailability and to identify sub-system degraders of overall engine reliability. While more complex means of assessing reliability exist, increased layers of complexity can lead to increasing difficulty when used to convince a military commander or fleet manager of the appropriate action to take. Furthermore, increased complexity increases the time required to produce, to analyze, and to assess results of reliability assessments. In a time-critical situation, when faced with the need for an immediate maintenance or engineering decision, the best information is that which is the simplest and easiest to understand, quickest to produce, and fastest to apply. In this work, a minimum list of data requirements will be developed with an associated means of analyzing these data to produce meaningful indicators to predict and to forecast unavailability and mission abort rates that can be used to plan for deployed or sustained operations. Analysis of the same data set can produce a prioritized listing of sub-system reliability degraders to drive engineering decisions for component improvement. The Royal Canadian Air Force’s CT114 Tutor aircraft will be the basis for analysis demonstrating that sophisticated sensors and data systems are not required to be able to produce meaningful data suitable for significant fleet level decisions. Statistical methods and appropriate data filtering were applied to the engine system to derive rates for overall mission aborts, aircraft unavailability and aircraft unreliability for the top sub-system degraders. Conclusions drawn include that this information, if calculated correctly, can provide decision makers with the critical information required to make significant fleet wide decisions. Recommendations and methodology are presented that are applicable to any military or civil aircraft fleet at the sub-system, aircraft, and fleet level.