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Instead of the Hamilton Standard constantspeed propeller you used in the AT-6, you now use a 3-bladed Curtiss Electric propeller. To maintain a constant engine speed, the angle of the blades in the Curtiss Electric is varied through an arc of 30' (from 24.5' to 54.5') by a propeller governor and electric motor. The current for operating the propeller governor and the electric motor comes from the battery and generator through propeller switches on the cockpit switch panel to the propeller control system.
The propeller is controlled by a breaker switch and a selector switch The breaker switch is an overload switch with ON and OFF positions. For all normal
You can operate the propeller automatically or manually. For all ordinary purposes you use automatic operation. Manual, or FIXED PITCH, operation is for emergencies.
When you operate the propeller automatically, the desired engine speed is held constant by a governor which is set by the propeller control on the throttle quadrant.
When you operate it manually, the blade angle is varied by means of a dashboard selector switch which is independent of the governor
operations, use the ON position. When there is an overload current on the propeller's electrical system, the breaker switch snaps to OFF. Should this happen, put the selector switch in FIXED PITCH. Wait 15 seconds and push the breaker switch back to ON.
Note: When the breaker switch goes to OFF during takeoff, don't wait. Push it back to ON immediately.
There are two types of breaker switches. The new type is a pop-out switch resembling a cigar lighter on an automobile dashboard. When it is out, its. red base is visible. Push it back to put it in the ON position. The old-type switch looks and works like an electric light switch.
