Plain English Meaning

How the engine is running — whether it sounds right, responds correctly to control inputs, and shows normal readings on the gauges.

Full Definition

The running condition of the airplane's engine during a specific phase of flight or ground operation, evaluated by checking instrument indications (RPM, manifold pressure, oil pressure, oil temperature, fuel flow, EGT, etc.), engine response to throttle and mixture inputs, and the absence of roughness, vibration, or unusual sounds. During the before-takeoff check, engine operation is confirmed to be smooth, within published limits, and producing the expected before the airplane is committed to .