The motoring wash is carried out at what engine speed range?

• A. Engine speeds of 14% to 25%
• B. 60% to 80%
• C. 30% to 50%
• D. 0% to 5%

Answer: (A)

Motoring wash uses the starter to rotate the engine while circulating the wash fluid through the core with no ignition. This must be done at a low, controlled speed so the airflow drives the cleaning solution through the entire core without pushing the engine into combustion or unstable rotor behavior. In this low-speed window, the compressor operates in a stable part of its map, allowing the wash to flow evenly through the compressor, combustor, and turbines to flush out deposits. If the speed is too high, the risk of compressor surge and uneven flow rises; if it’s too low, the wash won’t adequately circulate through the core. So the best choice is the small, stable motoring range that provides enough flow for cleaning while staying out of surge risk.