Definition
A phrase used in mechanical and aviation maintenance specifications to describe how a fastener, nut, or component must be tightened to the point where it rotates together with the part it secures, with no relative movement between the two. It indicates a snug, drag-free fit rather than a torqued or locked condition.
Plain English
Tighten the part just enough that, if you move it, the thing it's attached to moves with it as one piece. Not loose, not cranked down hard — just snug enough that they act together.
Context Anchor
Seen in aircraft maintenance descriptions of shafts, gears, pulleys, propeller parts, and other rotating assemblies.
Why Pilots Care
Misreading this instruction can lead to over-tightening (which binds moving parts) or under-tightening (which allows play and wear). On flight controls and rigging, getting this fit right preserves smooth, free movement while eliminating slop.
Intuition Check
Do not read this as simply “near a part that is turning.” It means the parts are connected so the turning motion is carried from one part to the other.
Example Sentence 1
The manual instructed the mechanic to tighten the castellated nut so that it turns with it, then back off to the next slot for the cotter pin.
Example Sentence 2
Install the collar and tighten the setscrew so that it turns with it during engine operation.