Propellers, Governors and Control Rigging

A fixed-pitch propeller is a single compromise: a climb propeller bites coarse air at low speed while a cruise propeller runs fast and flat, so the choice depends on the mission. A constant-speed propeller changes blade pitch through a governor that meters oil to the hub, with a single-acting governor balancing oil pressure against counterweights and springs, holding the selected rpm as the throttle moves.

Cycling the propeller during run-up flushes cold oil out of the hub and confirms governor operation. On turboprops, feathering turns the blades edge-on after a failure so the windmill cannot drive the engine, and beta and reverse shorten the blade to help stop the aircraft.

Inspection is tactile. Leading-edge nicks are stress risers: blend them within the manual limits and never file across the blade. Check blade track, the aerodynamic twist, spinner and bulkhead cracks, hub grease condition and control rigging. A prop strike or overspeed mandates the teardown inspection required by the manufacturer, with no exceptions regardless of how smoothly the propeller still runs.