Definition
The thick, rounded base end of a propeller blade — the part that fits into the propeller hub and is held in place there. It is the end opposite the blade tip.
Plain English
The fat inner end of a propeller blade that plugs into the hub at the center of the propeller.
Context Anchor
Seen in propeller and rotor maintenance, inspection, and repair discussions.
Derivation
‘Butt’ here is the old English sense meaning the thicker or blunt end of an object — the same use as in ‘rifle butt’ or ‘the butt of a tool.’ It marks the heavy, anchored end as opposed to the working tip.
Why Pilots Care
This attachment point carries all flight loads; any damage or improper installation can lead to catastrophic rotor failure.
Analogy
Think of a ceiling fan blade: the blade butt is the end bolted near the center, not the outer end moving through the air.
Intuition Check
Do not read butt here as slang or as the rear of the aircraft. In this term, it means the thick inner end of the blade where it attaches.
Example Sentence 1
During the propeller overhaul, the technician inspected each blade butt for cracks before reinstalling the blades in the hub.
Example Sentence 2
Proper torque on the blade butt bolts is essential for safe operation of the main rotor.