AME Aircraft Propeller Systems and Theory 2 — Questions and Answers
Question 1: What is 'blade angle' in propeller terminology?
- The angle between the blade chord line and the plane of rotation (Correct answer)
- The angle between the leading edge and trailing edge
- The angle at which the propeller is mounted on the engine shaft
- The sweep angle of the blade from root to tip
Correct answer: The angle between the blade chord line and the plane of rotation
Blade angle (pitch angle) is measured between the blade chord line and the plane of rotation, determining how much air is deflected with each revolution.
Question 2: 'Geometric pitch' of a propeller is defined as:
- The actual distance the propeller advances per revolution
- The theoretical distance the propeller would advance per revolution with no slippage (Correct answer)
- The blade angle measured at the tip
- The diameter of the propeller disc
Correct answer: The theoretical distance the propeller would advance per revolution with no slippage
Geometric pitch is the theoretical advance per revolution based on blade angle alone, whereas effective pitch accounts for actual slippage through the air.
Question 3: Which FAA regulation governs the type certification of propellers?
- 14 CFR Part 21
- 14 CFR Part 23
- 14 CFR Part 35 (Correct answer)
- 14 CFR Part 43
Correct answer: 14 CFR Part 35
14 CFR Part 35 establishes the airworthiness standards specifically for propeller type certification in the United States.
Question 4: A propeller exhibiting excessive vibration during ground runup most likely indicates:
- Low engine oil pressure
- Dynamic imbalance or damaged blades (Correct answer)
- Incorrect fuel-air mixture
- Magneto timing error
Correct answer: Dynamic imbalance or damaged blades
Excessive vibration during runup typically points to propeller dynamic imbalance, a bent blade, or damage that disrupts the even distribution of rotating mass.
Question 5: What is the typical repair method for minor nicks and gouges on aluminum propeller blade leading edges?
- Welding or brazing the damaged area
- Filing the nick smooth and blending it into the blade profile (Correct answer)
- Replacing the blade immediately regardless of size
- Applying epoxy filler to restore the original contour
Correct answer: Filing the nick smooth and blending it into the blade profile
Minor nicks on aluminum propeller blades are repaired by carefully filing them smooth and blending the edges to prevent stress concentration and fatigue cracking.
Question 6: What is 'propeller slip'?
- The difference between geometric pitch and effective pitch (Correct answer)
- Movement of the propeller hub on the engine shaft
- Blade flex under high power settings
- Loss of traction during ground operations on wet surfaces
Correct answer: The difference between geometric pitch and effective pitch
Propeller slip is the difference between the theoretical geometric pitch and the actual effective pitch, representing the propeller's inefficiency due to airflow interaction.
AME Aircraft Propeller Systems and Theory 2
What is 'blade angle' in propeller terminology?