An Integrated, Real-Time Oil Quality Monitor and Debris Measurement Capability for Drive train and Engine Systems

The health of rotorcraft drive train and engine systems is paramount to providing safe operating, high readiness aircraft to the warfighter1,2,3. To determine this health, the rotorcraft gearbox, a sub-component of the drive train system, must be continuously monitored. Offline oil analysis and chip detection sensors have been employed in legacy gearboxes to this end. Oil analysis can provide valuable insight into the health and operation of a gearbox as well as a verification that the lubricant itself is within specification and still able to prevent wear. Metallic debris monitoring is the gold standard for fatigue spall detection and is a well accepted method for helping to ensure flightworthiness. The challenges associated with offline oil analysis, to include the complex and high cost logistics trail it incurs for in theater aircraft, make an online sensing technology for gearbox oil quality and debris highly desirable. To this end, Impact Technologies LLC and GasTOPS Inc are collaborating on a US Army RDECOM and AATD program to explore and test the viability of a combined online oil quality and metallic debris monitoring system for rotorcraft gearboxes. Development vision is for a single sensor that integrates real time oil quality monitoring, ferrous and non-ferrous metallic debris detection, and provisions for particle capture and extraction for at-line spectroscopic wear particle identification. The technical merit of each of the included technologies with respect to rotorcraft gearbox applications was evaluated in a laboratory test stand representative of the rotorcraft gearbox environment. Empirical results of this testing indicated that the included sensing technologies could successfully capture the lubricant and gearbox prognostic indicators of primary interest in their current instantiations. The feasibility of mechanical and electrical integration of these existing sensing technologies was explored, and several preliminary designs for the combined sensor that met the system's outlined criteria were successfully created. These concepts were scored with respect to the ultimate goals for the integrated sensor, namely their ability to directly replace legacy chip detectors and to do so without incurring additional weight penalties. The following paper outlines the team's experiences, and the program's progress, in pursuit of an integrated sensor that meets those goals.