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Diagnostics and Prognostics Group Researchers Win 2015 Prognostics & Health Management Society Conference Best Poster Award
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Diagnostics and Prognostics Group Researchers Win 2015 Prognostics & Health Management Society Conference Best Poster Award

A joint paper/poster entitled, “Hardware Development for the Controlled Fault Injection in a Turbofan Engine Air-Bleed Valve," written by members of the Diagnostics and Prognostics Group and a researcher from NASA Glenn’s Intelligent Control and Autonomy Branch, won the 2015 Prognostics and Health Management (PHM) Society Conference Best Poster Award. The work details hardware developed within the NASA Ames Prognostics Center of Excellence that has been integrated with a C-17 aircraft for fault-seeding of an air-bleed valve system on a Pratt & Whitney F117 high-bypass turbofan engine during the Vehicle Integrated Propulsion Research (VIPR) demonstration at NASA Armstrong Flight Research Center this summer.

The developed technology, an air-Bleed valve Override Box (BOB), nondestructively injects a fault into the air-bleed valve system and allows the user to control the progression of the fault during ground-based, on-wing tests of the engine at speed. In particular, the BOB interrupts and overrides the command of the valve from the engine’s control computer and simulates (safely and non-destructively) the progressive degradation of the valve actuator. Under this simulated fault condition, the actuator can be biased towards its failsafe position, causing a decrease in engine efficiency without compromising engine operability. To override control of the valve system, the BOB creates a control loop employing an independent controller, which generates a driving current for the valve, and uses the native aircraft Aeronautical Radio INC. (ARINC) 429 data bus to receive valve position feedback directly from the engine.

BACKGROUND: Operational data of progressive failure within engines of commercial aircraft that have associated ground truth of the actual magnitude of the fault are generally unavailable. This has to do mostly with scheduled maintenance that remediates the fault condition when it is first seen by sensors. Laboratory bench testing of the hardware is largely infeasible due to prohibitive cost and, at any rate, may not fully represent system-level effects.

This summer, the Vehicle Integrated Propulsion Research (VIPR) experiments took place at NASA Armstrong Flight Research Center. These experiments involved stationary ground-based, on-wing engine demonstrations that provided a means to test and evaluate emerging health management technologies on an aircraft engine, including new sensors and diagnostic algorithms. These tests were completed on a C-17 aircraft equipped with Pratt & Whitney F117 high-bypass turbofan engines. The first and second VIPR tests, which occurred in 2011 and 2013 respectively, introduced non-damaging gas-path fault scenarios into one of the engines installed on the aircraft. The final test campaign, VIPR 3, occurred in July 2015, culminating in volcanic ash ingestion tests. As part of VIPR 3, a prognostics experiment was developed to seed a controlled fault with increasing magnitude in the valve system while monitoring the engine for performance changes.

PROGRAM FUNDING: Convergent Aeronautics Solutions (CAS), Transformative Aeronautics Concepts Program (TACP), Aeronautics Research Mission Directorate (ARMD)

TEAM: Kai Goebel, George Gorospe (SGT), and Donald Simon (GRC)

POC: George Gorospe, george.e.gorospe@nasa.gov

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