FAA Flight Instructor Airplane (FIA)Aircraft Systems and InstrumentsHard
A turboprop pilot experiences a complete engine failure in cruise flight. To minimize drag and prevent damage from windmilling, the pilot should expect the propeller to move toward which position, and by what system is this accomplished?
- AFlat pitch, accomplished by the governor reducing oil pressure to the propeller dome
- BFull fine pitch, accomplished by centrifugal twisting moment alone
- CFull reverse pitch, accomplished by the beta control system
- DFeathered position, accomplished by high-pressure oil driven by a feathering pump acting against counterweights or a spring
Show answer & explanationAnswer & explanation
Correct answer: D. Feathered position, accomplished by high-pressure oil driven by a feathering pump acting against counterweights or a spring
Feathering rotates the propeller blades to an edge-on position relative to the relative wind, minimizing drag and preventing windmilling after an engine failure. This is typically accomplished using high-pressure oil from a feathering pump (or accumulator) that overcomes counterweights or springs designed to drive blades toward feather when normal governor oil pressure is lost.
Why the other options are wrong
- A. Flat pitch increases drag and would worsen windmilling, the opposite of the desired response.
- B. Centrifugal twisting moment alone cannot move blades to feather; a powered mechanism is required.
- C. Reverse pitch is used for ground braking, not in-flight failure response.
Propeller Feathering System
A system that rotates propeller blades to an edge-on (feathered) position after engine failure to minimize drag and prevent windmilling damage.
- Uses high-pressure oil from a feathering pump or accumulator
- Counterweights or springs assist movement to feather
- Common on turboprop and some twin piston aircraft
Memory trick: 'Feather like a knife edge slicing into the wind—drag disappears'