Definition
A loss of engine power, either partial or complete, that prevents the engine from producing the thrust needed for normal flight. In single-engine airplanes this means the airplane can no longer climb or maintain altitude under power and must be flown as a glider to a forced landing. In multi-engine airplanes it refers to the failure of one or more of the installed engines.
Plain English
The engine stops working properly, either dying completely or losing enough power that the airplane can't fly normally on it.
Context Anchor
Seen in takeoff and initial climb discussions, where loss of engine power requires an immediate change from climbing to safely landing.
Derivation
Powerplant' is the aviation term for the engine and the systems that make it run (fuel, ignition, propeller, etc.) — the 'plant' that produces 'power.' 'Failure' here means stopping or no longer doing its job. Together: the engine and its supporting systems have stopped delivering usable power.
Why Pilots Care
At low altitude there is little time or height to troubleshoot, so the pilot must immediately establish best glide speed and prepare for a forced landing.
Intuition Check
Failure does not always mean the engine has completely stopped. It can also mean the engine is running but not producing enough usable power.
Example Sentence 1
If a powerplant failure occurs during initial climb, the pilot's first action is to lower the nose to maintain a safe glide speed.
Example Sentence 2
In practice the instructor pulled the throttle to simulate a powerplant failure right after liftoff.