Definition
An automatic system on a multi-engine turboprop airplane that senses a sudden loss of power on one engine and, without pilot action, drives that engine's propeller blades to the feathered position to minimize drag.
Plain English
If one engine quits, this system automatically turns the dead engine's propeller blades edge-on to the wind so they stop windmilling and stop creating drag — without the pilot having to do anything.
Context Anchor
Seen in multiengine airplane training, especially when discussing engine failure, propeller drag, and minimum control speed with one engine not producing power.
Derivation
"Auto" from Greek autos meaning self, and "feather" from the propeller term meaning to align the blades edge-on to the airflow — like a feather lying flat in the wind. Together: a system that feathers the prop by itself.
Why Pilots Care
Rapid drag reduction improves single-engine climb performance and helps the pilot maintain directional control after an engine failure.
Grounding Statement
Picture one engine failing and its propeller being turned edge-on to the air so the airplane is no longer dragging a spinning disk through the sky.
Intuition Check
Autofeather does not restart the failed engine or add power. It reduces drag by changing the failed engine’s propeller blade angle.
Example Sentence 1
Before takeoff, the crew armed the autofeather system so it would activate if an engine failed during the climb.
Example Sentence 2
The crew confirmed the autofeather system was armed during the before-takeoff checklist on the twin-turboprop.