Definition
A propeller whose blade pitch can be changed only on the ground, with the engine stopped. The blades are loosened in the hub, rotated to the desired angle, and then secured before flight. Once set, the pitch remains fixed for the entire flight and cannot be altered by the pilot in the air.
Plain English
A propeller you can adjust, but only while the aircraft is parked. A mechanic loosens the blades, twists them to a new angle, and tightens them again. After that, the propeller behaves like a fixed-pitch propeller until someone changes it on the ground next time.
Context Anchor
Seen in propeller descriptions, aircraft equipment information, maintenance discussions, and performance planning for takeoff, climb, and cruise.
Derivation
Ground-adjustable' simply names when the adjustment can be made -- on the ground, not in flight. The phrase exists to distinguish it from in-flight controllable propellers, which appeared later in propeller development.
Why Pilots Care
Gives a simple way to tune climb or cruise performance for a given mission without the complexity or weight of an in-flight adjustable propeller.
Intuition Check
“Adjustable” does not mean adjustable from the cockpit in flight. “Ground-adjustable” means the propeller is adjusted before flight and then left at that setting during flight.
Example Sentence 1
The trainer was equipped with a ground-adjustable propeller, so any pitch change required a visit to the maintenance hangar.
Example Sentence 2
Many light sport aircraft use ground-adjustable propellers so owners can optimize the blade angle for their typical missions.