About this calculator
Measure the stack, choose the diameter, the load and the head: the selector gives the Hi-Lok pin part number with its grip dash, the collars the quick reference pairs with it, the shank size, the pin length and the hex key, and the fit the FAA handbook asks for.
Runs in your browser. Inches or millimetres at the top.
How the part number works
HL18PB8-8: pin series HL18 (protruding shear head, alloy steel), finish PB, first dash 8 = nominal diameter 8/32 = 1/4 in, second dash 8 = maximum grip 8/16 = 1/2 in. The grip tolerance is ±0.005 in and the pin length is the maximum grip plus the B dimension of the drawing.
Oversize pins (HL62 and HL63 at 1/64 in, HL218 and HL219 at 1/32 in) keep the dash of the standard size they replace.
The collar's wrenching end shears off at its torque-off value, which sets the preload: there is nothing to check with a torque wrench afterwards.
Limits — when NOT to use this
- The hole size is not given. The maker's drawings prepare the hole to NAS618, which is not public. Take it from the SRM, the drawing or NAS618.
- The aircraft's drawing or SRM names the exact pin, collar and finish: use those. This selector is for reading and checking them.
- Collars HL83, HL297, HL386 and the HLT900 and HLT912 series are not tabulated here.
Sources
- Hi-Shear / LISI Aerospace drawings HL18 rev. 28, HL10 rev. 43, HL62 rev. 18, HL218 rev. 11 — part number code, shank and thread, head, B dimension, hex socket, strengths, grip tolerance.
- ECAS catalogue, Hi-Lok and collar quick reference — pin series by material, head and load, recommended collars, collar torque-off.
- FAA-H-8083-31A Airframe Handbook Vol. 1, Chapter 4 — Hi-Lok fit: interference not over 0.002 in in aluminium, clearance in steel, titanium and composite (p. 4-51).
- NASA PRC-9007C — grip check and one-step substitution.