On-Wing Engine Performance Monitoring and Alarming

Health and Usage Monitoring Systems (HUMS) have revolutionized many aspects of aircraft operation, functional check flight evolutions, and maintainability, and have inherently provided increased safety margin; however, few have capitalized on on-wing parameter alarming, including engine performance. Due to the increased frequency of operating our military aircraft in such locations as Afghanistan, Iraq, and aboard naval vessels where aircraft engines are inherently subjected to the most austere environments in terms of sand and salt water, accelerated engine performance degradation can be expected. Unlike foreign object damage (FOD) and blade failures, which in most cases creates a severe rotor 1/rev unbalance and are quickly discovered by vibration monitoring, sand and saltwater induced engine performance degradation is essentially transparent to vibration monitoring due to the uniform wear (sand erosion) and encrustation (salt water) induced circumferentially around the affected rotor. The only effective and efficient means to alert the aircrew of low engine performance conditions of this nature, outside of a protracted pilot-initiated performance check, is to capitalize on the monitoring and alarming features of the respective aircraft's HUMS.