Definition
The range of material thickness a fastener (such as a bolt, rivet, or Hi-Lok) is designed to clamp together. Grip range is specified as a minimum and maximum total thickness of the parts being joined, measured along the fastener's shank between the underside of the head and the start of the threads or tail.
Plain English
How thick a stack of parts a particular bolt or rivet is built to hold together. Each fastener works only within a specific thickness window — too thin and it won't clamp properly, too thick and the threads or tail won't reach.
Context Anchor
Seen in aircraft maintenance when selecting rivets, blind rivets, or other fasteners for sheet-metal or structural repairs.
Derivation
Grip refers to the part of the fastener that actually holds the joined materials, distinct from the threaded or upset portion. Range expresses the allowable minimum-to-maximum thickness the grip can accommodate.
Why Pilots Care
A fastener used outside its grip range will not clamp the structure correctly. Too short and the threads bear load they weren't designed for; too long and the joint won't pull tight. Either condition can lead to structural failure, so correct grip selection is critical during maintenance and inspection.
Intuition Check
Grip range does not mean how strong your hand grip is, or how tightly the fastener squeezes. It means the thickness span of material the fastener is made to fit.
Example Sentence 1
The mechanic measured the combined thickness of the skin and doubler, then selected a Hi-Lok with the correct grip range.
Example Sentence 2
Using a rivet outside its grip range can leave the joint loose or damage the materials.