Definition
An aerodynamic fairing fitted around the shank (root section) of a propeller blade where it meets the hub. The cuff gives the otherwise round, non-airfoil-shaped shank a wing-like cross-section so it can produce useful thrust and direct cooling air through the engine cowling.
Plain English
A shaped sleeve that wraps around the thick base of a propeller blade. Without it, the base of the blade is just a round bar that doesn't push air. With it, the base acts like a small wing and helps move air for thrust and engine cooling.
Context Anchor
Seen during propeller preflight checks, propeller maintenance, and discussions of engine cooling airflow.
Derivation
Cuff' comes from the Middle English 'cuffe,' meaning a covering wrapped around the wrist or end of a sleeve. The propeller cuff wraps around the base of the blade in the same way -- a fitted covering at the root.
Why Pilots Care
Blade cuffs can increase thrust at low speeds and help maintain propeller efficiency; damage or missing cuffs affect takeoff performance and vibration levels.
Intuition Check
Do not think of a blade cuff as a removable cover or a repair patch. It is a built-in or attached shaped fairing at the base of the propeller blade.
Example Sentence 1
During preflight, the pilot checked each blade cuff for cracks and confirmed it was secure against the hub.
Example Sentence 2
During the preflight walk-around the pilot checked each blade cuff for cracks that could cause imbalance.