Definition
The propeller dome is the rounded metal housing mounted on the front of the propeller hub that contains the pitch-change mechanism, including the piston, cylinder, and spring assembly used to change blade angle. On feathering propellers, it houses the components that drive the blades to and from the feathered position.
Plain English
It is the smooth, rounded metal cover on the very front of the propeller. Inside it sits the machinery that turns the blades to different angles, including the parts that move the blades into the feathered position when an engine is shut down in flight.
Context Anchor
Seen in discussions of feathering propellers, propeller governors, and how oil pressure changes blade angle.
Derivation
Dome' comes from the Latin 'domus' meaning house. The name fits because this part is literally the house that contains the pitch-change mechanism.
Why Pilots Care
Proper function of the propeller dome allows blades to feather quickly, minimizing drag and preventing further engine damage or loss of control after power loss.
Intuition Check
The propeller dome is not the same as the spinner. The spinner is mainly an outside fairing; the propeller dome is part of the blade-angle control system on propellers that use one.
Example Sentence 1
During preflight, the pilot checked the propeller dome for oil streaks, since a leak there could indicate a problem with the feathering mechanism.
Example Sentence 2
During preflight the pilot checked for oil leaks around the base of the propeller dome that could affect feathering operation.