A&P Propeller Systems and Maintenance 1 — Questions and Answers
Question 1: What is the primary function of a propeller governor in a constant-speed propeller system?
- To maintain constant blade pitch regardless of throttle position
- To maintain a constant engine RPM by varying blade pitch angle (Correct answer)
- To automatically feather the propeller during engine failure
- To prevent propeller overspeed by mechanically limiting blade travel
Correct answer: To maintain a constant engine RPM by varying blade pitch angle
The governor senses RPM and adjusts blade pitch — increasing or decreasing the angle — to maintain the pilot-selected RPM setting.
Question 2: Which blade pitch setting is used during takeoff on a constant-speed propeller to achieve maximum thrust?
- High pitch (coarse) angle to maximize propeller efficiency
- Feathered position to prevent torque effects during acceleration
- Low pitch (fine) angle to allow the engine to develop maximum RPM (Correct answer)
- Beta range to provide maximum blade bite at low airspeed
Correct answer: Low pitch (fine) angle to allow the engine to develop maximum RPM
A low-pitch (fine) angle allows the engine to reach its maximum rated RPM and power output, producing maximum thrust during takeoff.
Question 3: What does the term 'blade track' mean when applied to propeller inspection?
- The arc swept by each blade tip during one full rotation
- The angle each blade makes relative to the propeller hub center
- The spiral path of air accelerated behind the propeller disc
- The ability of all blades to follow the same plane of rotation (Correct answer)
Correct answer: The ability of all blades to follow the same plane of rotation
Blade track refers to whether all blade tips follow the same circular path during rotation, indicating proper blade alignment within the hub.
Question 4: What is the primary reason for feathering a propeller after an engine becomes inoperative in flight?
- To minimize aerodynamic drag and prevent windmilling of the failed engine (Correct answer)
- To increase drag and reduce aircraft speed for an emergency approach
- To cool the inoperative engine during the subsequent descent
- To lock the crankshaft and prevent further internal engine damage
Correct answer: To minimize aerodynamic drag and prevent windmilling of the failed engine
Feathering aligns the blade chord parallel to the airflow, minimizing drag and stopping windmilling that could cause further damage to the failed engine.
Question 5: What does 'effective pitch' mean in propeller terminology?
- The blade angle measured at the manufacturer-specified reference station
- The theoretical advance per revolution assuming no propeller slippage
- The actual distance the aircraft advances through the air per propeller revolution (Correct answer)
- The maximum pitch angle the variable-pitch propeller can achieve
Correct answer: The actual distance the aircraft advances through the air per propeller revolution
Effective pitch is the actual distance the propeller and aircraft advance through the air per revolution, accounting for slippage losses.
Question 6: At which station along the blade is propeller blade angle typically measured per FAA standards?
- 12 inches from the blade tip measured along the leading edge
- 42 inches from the propeller centerline measured radially
- 50% of the blade radius from the hub center
- 75% of the blade radius from the hub center (Correct answer)
Correct answer: 75% of the blade radius from the hub center
FAA standards specify that blade angle is measured at the 75% radius station from the hub center as the standard reference point for all propeller blade angle measurements.
Question 7: What does 'propeller slip' represent in terms of propeller performance?
- Physical slippage of the propeller hub on the engine crankshaft splines
- The difference between geometric pitch and effective pitch (Correct answer)
- Blade flutter caused by aerodynamic imbalance at high RPM
- A reduction in blade pitch angle that occurs under high power settings
Correct answer: The difference between geometric pitch and effective pitch
Propeller slip is the difference between geometric pitch (theoretical advance) and effective pitch (actual advance), representing the propeller's aerodynamic inefficiency.
A&P Propeller Systems and Maintenance 1
What is the primary function of a propeller governor in a constant-speed propeller system?