PROPELLER OVERSPEED GOVERNORS:
These devices protect against overspeed, they are separate governors to the P.C.U. and direct oil during an overspeed situation to coarsen the blade. Built into the device is an air bled which at max. RPM will back off the fuel flow from the fuel control unit.
The governor is equipped with a solenoid valve to enable its operation to be tested. When energised, the valve opens, allowing pressure oil to alter the position of the speed reset adjuster. Speeder spring compression is reduced by the upward movement of the adjuster and integral spring seat, which acts against the speed reset spring. Reduced spring force allows the flyweights to move out at a lower speed to simulate an overspeed condition. When the solenoid is de-energised, the oil supply to the adjuster bore is cut off, allowing the governor to function normally.