FAA Sport Pilot Airplane (SPA)Aircraft Performance and SystemsEasy
A sport pilot is flying a light sport airplane equipped with a fixed-pitch propeller and wants to increase engine RPM during cruise flight. Which action will accomplish this?
- AEnrich the mixture control
- BDecrease the throttle setting
- CIncrease the throttle setting
- DAdjust the propeller control lever to a lower blade angle
Show answer & explanationAnswer & explanation
Correct answer: C. Increase the throttle setting
Fixed-pitch propellers have no separate blade-angle control; RPM is controlled entirely by throttle (power) setting. Increasing throttle increases engine power and RPM together.
Why the other options are wrong
- A. Mixture affects fuel/air ratio, not RPM directly.
- B. Decreasing throttle would lower, not raise, RPM.
- D. Fixed-pitch propellers have no adjustable blade angle control lever.
Fixed-Pitch Propeller
A propeller with a set blade angle that cannot be changed in flight; engine RPM is controlled solely by throttle position.
- Common on most light sport airplanes
- Throttle position directly sets both power and RPM
- No separate propeller control lever exists
Memory trick: Fixed prop, one lever — throttle does it all.