Advanced Oil Filter Load Monitoring for Aircraft Engine Bearing Diagnostics

Early indication of impending main engine bearing failure is critical, especially for single engine fighter aircraft such as the F16. Bearing degradation leading to failure is characterized by increasing amounts of bearing spall debris entering the engine lubricant flow. Magnetic chip collectors are widely fielded to capture anomalous debris, but typically suffer low capture efficiency and lack online measurement capability. Aircraft engine lubrication filters, however, capture virtually all bearing damage particulates, making them well suited to perform a secondary role as debris monitoring sensing elements. To address the critical need for improved engine diagnostic capabilities, Luna Innovations is advancing the state of the art in filter monitoring by leveraging the technical experience of industry leaders to develop load sensing hardware and trending algorithms for particulate distributions specific to aircraft engine bearing damage. In Phase I, the team demonstrated filter loading sensitivity to less than five milligrams of bearing spall debris, and implemented methods for passively correcting the measurement for flow rate and thermal effects. The Phase II program will focus on tailoring filter construction to optimize sensitivity to bearing spall debris and developing an integrated hardware package suitable for evaluation on ground-based test stands. BENEFIT: Successful implementation of the proposed technology will provide aircraft operators and maintainers with critical information regarding the state of the main bearings as well as remaining filter life and important lubricant properties. In addition to the clear benefits of such a system for DoD aircraft engines, potential commercial application for this technology is broad. Any sizable, expensive, and/or critical mechanical system that requires lubricant circulation is certain to employ filtration to mitigate abrasive wear of the components, including power generation rotating equipment, commercial aviation hydraulic and engine lubrication systems, and large truck engines. The advanced oil filter load monitoring system developed under the proposed program would be directly applicable to those systems where the anticipated failure modes involve significant debris generation within the fluid circulation system. The diagnostic information provided by the system would enhance condition-based maintenance strategies, reducing ownership costs over the life of the equipment. A key enabling benefit of this technology is that the necessary hardware is readily installed using existing fluid connections and is minimally invasive, limited to the original oil filter location.