...A propeller brake for a twin spool turbo-prop engine which permits the propeller to be locked in a stationary position with the engine running is disclosed. The propeller brake has a hydraulically actuated friction brake and hydraulically actuated locking mechanism rotatably connected to the engine spool turning the propeller. The friction brake stops the propeller from rotating in response to an external command. A hydraulic signal indicating the propeller has stopped rotating actuates the mechanical lock holding the propeller in a stationary position. A safety latch prevents the mechanical lock from being actuated in event of a hydraulic pressure or engine failure in flight.
