What it is
Where to buyFAA-H-8083-31B (pp. 4-54, 4-55) names Jo-Bolts, Visu-Lok, Composi-Lok, OSI Bolt and Radial-Lok as drive-nut blind bolts for high-strength joints where the blind side cannot be reached. In all of them the screw advances through the nut body, the sleeve is drawn up over the tapered nose of the nut and forms against the blind side, and the screw fractures in its break groove.
The stem of the OSI Bolt and of the newer Composi-Lok 3 breaks off flush, whereas that of Jo-Bolts, Visu-Lok and Composi-Lok II does not and needs the break-off shaver tool where a flush installation is required (p. 4-55).
Installing a drive-nut blind bolt
| Step | What | Source |
|---|---|---|
| 1 · Hole | To the maker's data for the type | Maker / SRM |
| 2 · Grip | Measure the stack with the grip gauge for the type; the grip is critical | FAA-H-8083-31B p. 4-54 |
| 3 · Insert | Fastener in the hole, tool over the screw and the nut | p. 4-54 |
| 4 · Drive | Hold the nut and apply torque to the screw until the sleeve forms against the blind side and the screw breaks in its groove | p. 4-55 |
| 5 · Finish | The OSI Bolt stem breaks off flush; no shaving | p. 4-55 |
Blind bolts are difficult to remove because of the hardness of the core bolt; a special removal kit is available from the manufacturer for each type (p. 4-52).
Questions people actually ask
Does the OSI Bolt need the shaver tool?
No. Its stem breaks off flush (FAA-H-8083-31B p. 4-55).
Which hole?
The maker's data or the SRM: no public hole table was found for it.
Limits of this guide
What the sources support, and no further.
- No part number, hole, grip or strength table for the OSI Bolt was found in a public text.
- No cross number to an ASNA or NAS standard was found.
- Oversize and titanium versions are not described in the sources used.
- Reference data, not approved data. The SRM, the drawing or the approved repair data governs over every figure here.
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Sources
- FAA-H-8083-31B, Aviation Maintenance Technician Handbook, Airframe, chapter 4 — Pp. 4-52, 4-54, 4-55: blind bolts, drive-nut installation, flush break.