Threaded inserts (key-locked MS51830 / Keenserts, helical coil MS21209), generic-NAS
MS51830CA109L
Durable threads in a tapped hole, installed from one side: key-locked (MS51830, Keensert) or helical coil (MS21209).

- Style Key-locked insert, coarse internal threads
- Internal / external thread internal .4375-14 UNJC-3B, external .5625-12UNC-2A
- Length L length L .562" ±.015
- Material CRES type A286 (CA), heat treated…
- Lead-time risk Medium
| Family | Threaded inserts (key-locked MS51830 / Keenserts, helical coil MS21209) (generic-NAS) |
|---|---|
| Style | Key-locked insert, coarse internal threads (source: MS51830F Table I) |
| Internal / external thread | internal .4375-14 UNJC-3B, external .5625-12UNC-2A |
| Length L | length L .562" ±.015 |
| Material | CRES type A286 (CA), heat treated to 140,000 psi Ftu minimum |
Decoded from the published numbering scheme; not a claim that this exact part number is a stocked SKU, and not a certified design authority. Always verify against the controlling drawing and spec.
Series and loads (datasheet)
MS51830[-|CA|A][dash][L|LM] · e.g. MS51830CA106L (key-locked) · MS21209C0415 (helical coil, screw locking)
Key-locked MS51830, ultimate pullout load lbs (non-locked / internal thread lock part): .190 internal 4,095 / 2,551; .250: 6,401 / 4,660; .375: 11,607 / 9,088; .500: 19,364 / 15,743, where "Pullout load = (Shear engagement area) x (27,000 psi)" (MIL-I-45914A Table III, p.8). Torque out, inch-pounds, MS51830: .250 120; .500 600 (Table VI, p.11). Helical coil screw locking, .250-20: 30 max locking / 4.5 min breakaway, pound-inches at room temperature (MIL-I-8846D Table II, p.5).
Other MS51830 part numbers
Sizes listed in MS51830F w/Amendment 1, Tables I and II, Requirement 7 ↗
Threaded insert · 2 steps
1/2Hole prepared
“Hole preparation in accordance with Tables I, II and III per applicable thread size of part and corresponding dash number.”
MS51835B (key-locked insert hole and assembly), p.5, Figure 2 requirements ↗
Drawing traced from: Figure 1, Configuration for Tables I, II and III.
Source images (3): patent and government drawings
A patent drawing shows the patented design, which can differ in detail from today's catalog part. Each image says why it is tied to this family.



Install tooling: LDS-7 (Howmet Keysert and Keensert catalog, p.11, Miniature and Lightweight Keenserts, Installation and Removal columns)
Decode details
| Series | MS51830 key-locked insert, miniature and lightweight |
|---|---|
| Decode confidence | high |
| Numbering source | MS51830F w/Amendment 1, Requirement 7; Tables I and II |
- "Example: MS51830CA106L indicates -Insert, Screw-Thread, Locked In, Key-Locked, Lightweight, CRES A286, .250-20UNJC-3B internal thread with internal thread lock feature." (Requirement 7)
- L = "internal thread lock for aerospace applications".
- "Installation of inserts shall be in accordance with MS51835." (Note 2)
Lead-time risk for this family (SpecLok sourcing assessment): Medium
Image credits: Howmet Aerospace, Keenserts® General Purpose Inserts (catalog.howmetfasteners.com) ↗. Product images belong to their manufacturers.
Sources
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