What controls the constant-speed range of a constant-speed propeller?

• A. The governor spring tension
• B. The mechanical limits in the propeller pitch range
• C. Engine RPM
• D. Hydraulic pressure

Answer: (B)

Constant-speed propellers maintain a selected RPM by changing blade pitch to balance engine torque and air resistance. The range over which this constant speed can be held is limited by how far the blades can actually move—the mechanical stops and travel built into the propeller pitch mechanism define the usable pitch range. Within those physical limits, the governor can adjust pitch in response to RPM deviations; outside them, no further adjustment is possible and the speed can drift.

So, the constant-speed range is determined by the mechanical limits in the propeller pitch range—the range of blade angles the system can achieve. The governor spring tension and hydraulic pressure enable movement within that range, but they do not set how far the blades can move. Engine RPM is what’s controlled, not the range itself.