aircraft systemsFAA-published sample question (AGI, Aug 2021)
The reason for variations in geometric pitch (twisting) along a propeller blade is that it
A
prevents the portion of the blade near the hub to stall during cruising flight.
B
permits a relatively constant angle of attack along its length when in cruising flight.✓ Correct Answer
C
permits a relatively constant angle of incidence along its length when in cruising flight.
Explanation
Each section of a propeller blade moves at a different speed, faster toward the tip, so PHAK explains the blade is twisted (higher blade angle near the hub, lower near the tip) to keep a relatively constant angle of attack along its length in cruise. The twist exists to equalize angle of attack, not angle of incidence.
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