Originally Posted by
Chris Scott
I imagine the auto-feathering system would look at BMEP and throttle angle? On take-off, with the throttle at or somewhere near the gate, a critical loss of BMEP would presumably activate auto-feathering. But we know the captain commented that the auto-feathering light was not working [report, 1.1.12]. I'm unable to identify the light he was referring to on the photo posted by megan, but would there not be a separate one for each engine? Maybe the auto-feathering system was inoperative, at least on the No.1 (L/H) engine.
The autofeather system is armed by raising the guard and then the switch under it found at the center of the pedestal aft of the prop controls. There is one green light to the left of the switch that indicates the system is armed. When the throttles are advanced to a point that equates to ~45 inches MAP and the BMEP drops below ~70 for more than one second a solenoid pulls the feather button in and the prop feathers as if the feather button was pushed. The system also then disarms to prevent autofeathering the other prop.