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Aircraft Rivets
Solid and blind rivets, alloy codes and ice-box rivets, sizing and edge distance, defects and removal.
Aircraft rivets — summary notes
FreeMain ideas
- Solid rivets are the classic airframe fastener, set by forming a shop (bucked) head opposite the manufactured head. Heads are either universal (protruding) or countersunk (100°, flush for aerodynamic surfaces). Alloy/temper is shown by a head marking (e.g. plain, dimple, raised dot).
- Rivet codes: 2117 ('AD') is driven as received; 2024 ('DD') 'ice-box' rivets are solution-treated and kept refrigerated to stay soft, and must be driven within a time limit before they age-harden.
- Sizing rules of thumb: rivet diameter ≈ 3× the thickness of the thicker sheet; length gives a formed head about 1.5× diameter across and 0.5× diameter high; minimum edge distance ~2× diameter, with pitch/spacing limits to prevent tear-out.
- Blind (pop) rivets are set from one side where a bucking bar cannot reach — a mandrel pulls up the blind head (Cherry, etc.). Special fasteners include Hi-Lok, Hi-Shear, lockbolts and rivnuts; interference-fit fasteners improve fatigue life.
- Defects and removal: a 'smoking' rivet (dark smear) is working loose; tipped, clinched, cracked or over/under-driven heads are rejectable. Remove by drilling the head with a drill the size of the shank and snapping it off — without enlarging the hole.
- ⚠ Exam trap: 2024-DD 'ice-box' rivets are refrigerated to delay age-hardening so they stay drivable; once aged past the limit they must be re-heat-treated. Edge distance is measured from the hole CENTRE to the sheet edge (~2× diameter minimum).
Solved examples
An inspector finds a rivet in a wing skin surrounded by a dark, smudged halo. What does it indicate and what is the action?
That is a 'smoking' rivet — the dark trail is fretting debris from a rivet that has worked loose and is moving in its hole, a sign of a failing joint under fatigue. It must be investigated: the loose rivet(s) are removed by drilling out the head without enlarging the hole, the hole and structure inspected, and correctly replaced per the SRM.
Rivets concept map
FreeAircraft Rivets
Aircraft rivets quiz
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