SYSTEM AND METHOD FOR TESTING ENGINE PERFORMANCE IN-FLIGHT

Systems and methods (300) for testing engine performance in-flight in an aircraft (1) having a first engine (10A) and a second engine (10B) comprise operating the first engine (10A) at a first power level in an output speed governing mode, operating the second engine (10B) at a second power level greater than the first power level in a core speed governing mode concurrently with the first engine (10A) operating at the first power level in the output speed governing mode, and performing an engine performance test on the second engine (10B) while the second engine (10B) is at the second power level in the core speed governing mode.