Drawing
Selection table
One row per thread size, with its own link (/parts/nutplates/ms21049/#MS21049-08). The part number shown is the dry film lubricated, plain-hole form; the letters below change finish and holes, not size.
| Part no. | Thread | A max | B max | C | J | H max | Ø K | Ø P ±.005 | V max | Axial, lbf min | lb / 100 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| MS21049L08 | 8-32 | .948 | .422 | .344 | .688 | .272 | .098 | .365 | .047 | 1,720 | .39 |
| MS21049L3 | 10-32 | .948 | .453 | .344 | .688 | .281 | .098 | .411 | .047 | 2,460 | .41 |
| MS21049L4 | 1/4-28 | 1.260 | .619 | .500 | 1.000 | .340 | .098 | .540 | .055 | 4,580 | .88 |
| MS21049L5 | 5/16-24 | 1.292 | .766 | .500 | 1.000 | .422 | .130 | .686 | .065 | 7,390 | 1.17 |
Inches. From Table I of MS21049 Rev. F (15 Feb 1994). C ±.005, J ±.002, K +.005 −.000 as toleranced on the sheet. Ø P is nominal, ±.005 in. Weight is the standard's figure per 100 pieces. Rows shown are the sizes this sheet covers; the standard may list more.
How to read the part number
| Part no. | Meaning |
|---|---|
| MS21049-4 | Plain rivet holes, no dry film lubricant |
| MS21049L4 | Dry film lubricant (L) |
| MS21049-4K | Countersunk or dimpled rivet holes (K) |
| MS21049L4K | Both |
K (countersunk or dimpled rivet holes) is listed for dash 08, 3, 4, 5. Without lubricant the L becomes a dash.
What it is for
Fixed self-locking nutplate with 100° countersunk base for flush installation in dimpled or countersunk skin. Rated to 450 °F.
Rivet hole spacing J differs between nutplate types and sizes: check J before installing on an existing hole pattern.
Choose the size from the screw thread, then confirm J and C against the hole pattern and the edge distance of the flange it rivets to.
Limits — when NOT to use this
- Approved data governs. Use the nutplate and rivets the maintenance manual or IPC specifies.
- The MS sheet is a public-domain revision. These MS standards were later replaced by NASM equivalents. Check the current revision before buying to a drawing.
- Grip with nutplates. Where the proper bolt grip is not available, AC 43.13-1B par. 7-37 says to add shims under the plate, not washers.
- Rivets for the lugs, and their edge distance, come from the repair data, not from this sheet.
Sources
- MS21049 Rev. F, 15 Feb 1994 — Nutplate, Self-Locking, Two Lug, Low Height, 100° Countersunk — Table I, dash numbers and dimensions; notes and requirements. Public domain, distribution unlimited.
- FAA AC 43.13-1B, par. 7-37 — shims, not washers, under plate nuts.