NAS 1352 A286 Socket Head Cap Screws (NASM 1352)
NAS 1352 is the National Aerospace Standard (now maintained as NASM 1352 / SAE-AS 1352) for coarse-thread internally-wrenching socket-head cap screws cold-headed from A286 (UNS S66286) precipitation-hardening austenitic stainless steel superalloy. The spec defines the head, drive, and thread geometry that turbine-engine and airframe procurement engineers reference when specifying a corrosion-resistant high-strength fastener for use up to 700 degree C (1300 degree F). NAS 1352 ships in inch sizes 8-32 UNC through 1-8 UNC and is interchangeable with the matching MS 16997 design when the material is qualified to AMS 5737. The mil-spec callout is read on every CFM56, V2500, GE9X, F135, and Trent assembly drawing where A286 socket cap screws appear.
Dimensional Reference (per NASM 1352 head profile)
| Thread Size | Head Diameter (max) | Head Height (max) | Hex Socket Size | Body Diameter |
|---|---|---|---|---|
| 8-32 UNC | 0.270 in (6.86 mm) | 0.164 in (4.17 mm) | 9/64 in (3.57 mm) | 0.164 in (4.17 mm) |
| 10-32 UNC | 0.312 in (7.92 mm) | 0.190 in (4.83 mm) | 5/32 in (3.97 mm) | 0.190 in (4.83 mm) |
| 1/4-20 UNC | 0.375 in (9.53 mm) | 0.250 in (6.35 mm) | 3/16 in (4.76 mm) | 0.250 in (6.35 mm) |
| 5/16-18 UNC | 0.469 in (11.91 mm) | 0.312 in (7.92 mm) | 1/4 in (6.35 mm) | 0.312 in (7.92 mm) |
| 3/8-16 UNC | 0.562 in (14.27 mm) | 0.375 in (9.53 mm) | 5/16 in (7.94 mm) | 0.375 in (9.53 mm) |
| 7/16-14 UNC | 0.656 in (16.66 mm) | 0.438 in (11.13 mm) | 3/8 in (9.53 mm) | 0.438 in (11.13 mm) |
| 1/2-13 UNC | 0.750 in (19.05 mm) | 0.500 in (12.70 mm) | 3/8 in (9.53 mm) | 0.500 in (12.70 mm) |
| 5/8-11 UNC | 0.938 in (23.83 mm) | 0.625 in (15.88 mm) | 1/2 in (12.70 mm) | 0.625 in (15.88 mm) |
| 3/4-10 UNC | 1.125 in (28.58 mm) | 0.750 in (19.05 mm) | 5/8 in (15.88 mm) | 0.750 in (19.05 mm) |
| 1-8 UNC | 1.500 in (38.10 mm) | 1.000 in (25.40 mm) | 3/4 in (19.05 mm) | 1.000 in (25.40 mm) |
Dimensions per NASM 1352 head profile, derived from ASME B18.3 socket-head cap screw envelope. Hex socket per ASME B18.3 Table 5.
Material Spec and Heat Treatment
| Property | NAS 1352 Material (A286 per AMS 5737) | Source |
|---|---|---|
| UNS Designation | S66286 | ASTM A453 |
| Bar Stock Spec | AMS 5737 (precision cold-heading bar) | SAE Aerospace |
| Condition | Precipitation-aged after cold heading | AMS 5737 |
| Tensile Strength (min) | 140 ksi (965 MPa) | ASTM A453 Class D |
| Yield Strength 0.2% (min) | 105 ksi (725 MPa) | ASTM A453 Class D |
| Elongation (4D, min) | 12 percent | ASTM A453 |
| Hardness (typical) | 32 HRC | Aged condition |
| Service Temperature (max) | 700 degree C (1300 degree F) | Below eta-phase formation |
NAS 1352 A286 socket head cap screws ship in the cold-headed and precipitation-aged condition. Heat treatment per AMS 5737 controls dimensional and metallurgical tolerance.
NAS 1352 vs NAS 1351 (Coarse vs Fine Thread)
| Attribute | NAS 1352 (this page) | NAS 1351 |
|---|---|---|
| Thread Series | UNC coarse (8 to 13 TPI typ) | UNJF fine (10 to 28 TPI typ) |
| Typical Use | General airframe + accessory | Critical preload + repeated assembly |
| Head Style | Socket head cap (hex socket) | Socket head cap (hex socket) |
| Material Callout | A286 per AMS 5737 | A286 per AMS 5737 |
| See Also | MS 16997 | MS 16995 |
NAS 1352 and NAS 1351 share the same head geometry, A286 material spec, and aerospace-quality requirements. Thread series and intended application differ.
Typical Applications
NAS 1352 A286 socket cap screws are specified on commercial-aerospace turbine engines (CFM56, V2500, GE90, GEnx, GE9X, Trent 700, Trent 1000), military-aerospace platforms (F135 for F-35, F119 for F-22), gas-turbine industrial engines (LM2500, LM6000, SGT-800), and on airframe accessory hardware where corrosion resistance matters more than the absolute strength of alloy-steel 12-point bolts. The fastener is also the default for jet-engine bracket-to-casing joints, accessory gearbox housing closures, and bleed-air valve attach points, where A286 non-magnetic behaviour and 700 degree C service capability eliminate the alternative materials (17-4 PH max 315 degree C, Inconel 718 over-spec for this stress range, alloy steel needs Cd plating that flashes above 230 degree C).
Frequently Asked Questions
What material is NAS 1352?
NAS 1352 socket head cap screws are cold-headed from A286 (UNS S66286), an iron-nickel-chromium precipitation-hardening austenitic stainless steel superalloy. The bar-stock feed material is procured to AMS 5737 (precision-aged bar with tight dimensional and heat-treatment tolerance suitable for cold heading). After cold heading the screw is solution treated and precipitation aged per AMS 5732 or AMS 5737 to deliver 140 ksi tensile / 105 ksi yield (ASTM A453 Class D).
What is the difference between NAS 1352 and NAS 1351?
NAS 1352 uses UNC coarse thread (8 to 13 threads per inch in typical sizes) and is the general-purpose airframe and accessory screw. NAS 1351 uses UNJF fine thread (10 to 28 threads per inch typical) and is preferred where the joint is repeatedly assembled and disassembled or where high preload precision is required. Both use the same socket-head cap geometry and the same A286 (AMS 5737) material. Cross-reference MS 16997 (NAS 1352 equivalent) and MS 16995 (NAS 1351 equivalent).
What torque is recommended for NAS 1352 fasteners?
NAS 1352 torque values depend on diameter, joint material, and lubrication. Per ASME PCC-1 Appendix A typical dry-thread torque for A286 socket cap screws in aluminium joints: 1/4-20 UNC = 8 ft-lb, 5/16-18 UNC = 16 ft-lb, 3/8-16 UNC = 28 ft-lb, 1/2-13 UNC = 65 ft-lb, 5/8-11 UNC = 130 ft-lb. Apply 70 percent of these values when nickel-bearing anti-seize is used on the threads, since friction is reduced and the same preload is achieved with lower input torque. Always verify against the assembly drawing torque callout, which supersedes these typical values.
Are NAS 1352 socket cap screws magnetic?
No. NAS 1352 cap screws are non-magnetic with relative magnetic permeability of approximately 1.005 in the precipitation-aged condition. This is a function of the underlying A286 austenitic structure, which retains the face-centred-cubic lattice and the corresponding non-magnetic behaviour after heat treatment. The non-magnetic property qualifies NAS 1352 for use in instrument housings, magnetic-resonance imaging hardware, and military electronic-warfare equipment where ferritic fastener inclusion would distort the magnetic field.
What is the equivalent military specification for NAS 1352?
MS 16997 is the closest mil-spec equivalent for NAS 1352. Both specs define a socket-head cap screw with the same hex-socket drive, head diameter, and head height profile. The material callout on MS 16997 also points at A286 per AMS 5737. NASM 1352 (the current SAE-Aerospace-published version of NAS 1352) supersedes the original NAS 1352 reference but the dimensional and material requirements are unchanged.
Related A286 Products and Specifications
Cross-reference within the A286 fastener family: NAS 1351 A286 fine-thread screws, A286 NAS-series bolts hub, A286 socket head cap screws, A286 aerospace fasteners, A286 jet engine fasteners, AMS 5737 precision bar (the feedstock), ASTM A453 Grade 660 (the bolting standard).
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