Thrust reversal - Turbo-propeller reverse pitch system

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Thrust reversal - Cold stream reverser system

Turbo-propeller reverse pitch system

Fig. 15-5 A propeller pitch control system.

18. As mentioned in para. A, reverse thrust action is affected  on  turbo-propeller  powered  aircraft  by changing the pitch of the propeller blades through a hydro-mechanical pitch control system (fig. 15-5). Movement of the throttle or power control lever directs oil from the control system to the propeller mechanism to reduce the blade angle to zero, and then through to negative (reverse) pitch. During throttle lever movement, the fuel to the engine is trimmed by the throttle valve, which is interconnect- ed to the pitch control unit, so that engine power and blade angle are co-ordinated to obtain the desired amount of reverse thrust. Reverse thrust action may also be used to manoeuvre a turbo-propeller aircraft backwards after it has been brought to rest.


19. Several safety factors are incorporated in the propeller control system for use in the event of propeller malfunction, and these devices are usually hydro-mechanical pitch locking devices or stops.