Propulsion System Diagnostic and Reasoning Technology Development

The Sikorsky Aircraft Corporation (SAC) and the U.S. Army Aviation Development Directorate (ADD) Aviation Applied Technology Directorate (AATD) are jointly sponsoring the Capability-Based Operations and Sustainment Technology-Aviation (COST-A) project. The objective of COST-A is to demonstrate an integrated set of high-value diagnostics, prognostics, and system health management technologies that reduce the maintenance burden imposed by the Army's rotorcraft fleet, while at the same time preserving safety and reliability. The program was divided into six different primary technical focus areas, with the propulsion system being one of those areas. The primary goal of the COST-A propulsion effort is to develop a robust set of diagnostic and prognostic algorithms that provide insight into the health of key components of a rotorcraft's propulsion system including the main engines and various critical Line Replaceable Units (LRUs). Separate diagnostic algorithms have been developed for key main engine LRUs such as the Hydro-Mechanical Unit (HMU), Anti-Ice / Start Bleed Valve (AISBV), Inlet Particle Separator (IPS) blower, pneumatic starter, and cross-bleed valves. Other diagnostic and prognostic algorithms have been developed or refined that focus on assessing the gas path health of the engine as a whole and of each of its major modules (gas generator and power turbine), and assessing sensor quality to identify biases. In addition, the Auxiliary Power Unit (APU) is the target of both gas path health and sensor quality diagnostics. Information from all of these algorithms is fused using a series of reasoning algorithms which translate condition indicator (CI) data into actionable information for maintenance decision support. In this paper, several of the aforementioned COST-A Propulsion technologies will be discussed in detail and an example failure scenario will be utilized to elaborate diagnostic and reasoner functionality.