Definition
The structural breaking, cracking, or separation of part or all of a propeller blade during operation. It can result from fatigue, impact damage (such as a stone or runway strike), corrosion, or improper repair, and may cause severe vibration, partial or total loss of thrust, and engine or airframe damage from imbalance.
Plain English
A piece of the propeller cracks or breaks off while the engine is running. This is dangerous because the propeller spins fast and any damage to it can cause heavy shaking and serious damage to the airplane.
Context Anchor
Encountered during preflight and before-takeoff checks when inspecting the propeller for small cuts, cracks, loose parts, or other damage before increasing engine power.
Derivation
Propeller comes from Latin propellere, meaning to drive forward. Blade originally referred to the flat cutting part of a tool; on an airplane, it means the shaped arm of the propeller. Failure means it no longer holds together or does its job.
Why Pilots Care
Blade failure produces extreme vibration that can lead to engine separation, loss of control, or forced landing.
Analogy
It is like a ceiling fan with part of one blade missing: it shakes because the weight and force are no longer even. On an airplane propeller, the forces are much greater, so the danger builds very quickly.
Grounding Statement
At takeoff power, the blades are spinning fast; if one cracks or loses a piece, the airplane can shake hard almost immediately.
Intuition Check
Do not read failure as only meaning the propeller stopped. A propeller blade failure usually means the blade itself has cracked, broken, or come apart; the propeller may still be spinning, but unsafely.
Example Sentence 1
During the preflight, the pilot ran a hand along each blade looking for nicks, knowing that small damage left untreated can lead to propeller blade failure.
Example Sentence 2
If propeller blade failure occurs after takeoff, the pilot reduces power and prepares for an emergency landing at the nearest suitable field.