Definition
A power setting on an operating engine of a multi-engine airplane that produces approximately the same drag as a propeller that has been feathered. It is used during multi-engine training to simulate an engine failure with a feathered propeller without actually shutting the engine down or feathering the prop.
Plain English
A reduced throttle setting that mimics what the airplane feels like when one engine has been shut down and its propeller blades have been turned edge-on to the wind. It lets instructors safely practice engine-out flying without really stopping the engine.
Context Anchor
Encountered in multiengine training when practicing engine-out procedures while keeping the engine running for safety and convenience.
Derivation
Zero thrust' means the engine is producing no net forward push -- the small amount of thrust it makes is just enough to offset the drag of the slowly windmilling propeller. 'Feather' comes from the idea of turning the propeller blades to slice the air edge-first, like a feather lying flat in the wind, so they create as little drag as possible.
Why Pilots Care
It lets pilots practice engine-failure handling and aircraft control with realistic drag while keeping the engine running and ready for immediate power if needed.
Grounding Statement
Picture one engine still running, but set so it no longer gives the airplane useful forward pull during practice.
Intuition Check
Zero thrust does not mean the engine is off. It means the engine is running but adjusted so it produces little or no useful forward pull, to imitate a feathered propeller for training.
Example Sentence 1
During the multi-engine checkride, the examiner reduced the right engine to zero thrust to simulate a feathered propeller, and the applicant identified, verified, and flew the airplane on the remaining engine.
Example Sentence 2
With zero thrust set on the right engine, the pilot maintained directional control and climbed at blue line.