Boeing Stearman PT-17 Engine Startup (Inertia Starter) Inertia starters work by rotating a pinion and moving it forward through centrifugal force towards the ring-gear. As it continues to spin, the teeth of the pinion lock into the ring-gear and crank the engine. A key advantage of inertia startering is that they automatically disengage once the engine has started. #aviation #aviationlovers #ultimateaviator #stearman #boeing #aeroplane | Ultimate Aviator