Definition
The position a movable component, control surface, or mechanism naturally settles into when no external force, control input, or system pressure is acting on it. It is the neutral or default state of the part before any operating load is applied.
Plain English
Where the part sits when nothing is pushing or pulling on it. Its resting, untouched position.
Context Anchor
Seen in aircraft maintenance manuals, system descriptions, and troubleshooting steps when a part’s normal starting position must be known.
Derivation
At-rest combines “at” with “rest,” meaning a state of not moving. The hyphen shows the words work together as a describing phrase: an at-rest position is the position a part has while it is at rest.
Why Pilots Care
Many rigging measurements, control travel checks, and system inspections start from the at-rest position. If the at-rest position is wrong, every measurement taken from it will also be wrong.
Intuition Check
Do not assume at-rest means “safe,” “stored,” or “ready for flight.” It simply means the position the part has when no operating force is moving it.
Example Sentence 1
With the hydraulic system depressurized, the technician measured control travel from the aileron's at-rest position.
Example Sentence 2
The constant-speed propeller unit is designed so the blades move to a higher-pitch at-rest position when oil pressure is lost.