Specifications
Surface Treatments
Certifications
- ISO 9001 - 2015 Certified
- PED 2014/68/EC
- NACE MR0175/ISO 15156-2
- NORSOK M-650
- DFAR
- MERKBLATT AD 2000 W2/W7/W10
A286 NAS Bolts
A286 NAS bolts are the National Aerospace Standard (NAS) precision-hardening superalloy fasteners — TorqBolt manufactures the full NAS 1351 / NAS 1352 (socket head cap), NAS 6203 / NAS 6204 (reduced-shank SHCS), NAS 6603-6620 (12-point bi-hex), and NAS 1303-1320 (short-form aerospace bolts) ranges. NAS standards are issued by the Aerospace Industries Association of America (AIA) and define dimensions, thread tolerance (MIL-S-8879 Class 3), material (A286 / UNS S66286 per AMS 5732), inspection (AS9102 first-article), and marking. Used on every modern US-built jet engine (GE, P&W, Honeywell), every US military airframe (Boeing, Lockheed Martin, Northrop), and most space-launch vehicles. Heat-treated to ASTM A453 grade 660 Class A for 130 ksi tensile / 95 ksi yield, magnetic permeability < 1.005, retained preload to 700 °C. See parent A286 bolts, sister CRES bolts, hex bolts, socket head cap screws, plus the broader MS / MIL-SPEC aerospace fasteners family.
About A286 NAS Bolts
NAS stands for National Aerospace Standard, a series of dimensional and material specifications published by AIA (Aerospace Industries Association). NAS bolts are the dominant precision-hardening fastener on US-built aerospace assemblies — each part number defines the geometry, material grade, thread tolerance, and inspection requirements. TorqBolt is a qualified NAS manufacturer with full AS9100D AQMS coverage, AS9102 first-article reporting, and lot serialization 1-N per BAC 5004 / NAS 100. NAS A286 bolts are forged from A286 bar (AMS 5731 / 5732), solution-treated 1650 °F + aged 1325 °F to ASTM A453 grade 660 Class A, MIL-S-8879 Class 3 thread tolerance, magnetic permeability verified < 1.005 per ASTM A342, head-stamped per the applicable NAS marking convention.
A286 NAS Bolt Series & Their Aerospace Use
TorqBolt produces every common NAS A286 bolt series. Each defines a specific head, drive, and dimensional family:
- NAS 1351 / NAS 1352 — Aerospace socket head cap screws (SHCS) — internal hex drive, cylindrical head, MIL-S-8879 thread. Standard sizes #4 to 1-1/2 inch. The most common CRES A286 fastener.
- NAS 6203 / NAS 6204 — Reduced-shank socket head cap screws — diameter under-head reduced to thread root for fatigue performance. Specified on engine accessory and high-cycle structural bolts.
- NAS 6603-6620 (also 6403-6420) — 12-point (bi-hex) flange bolts — high-torque transmission with reduced under-head height. Compressor disc and turbine wheel-shaft bolting on jet engines.
- NAS 1303-1320 — Short-form aerospace hex bolts — internal-wrenching designs for limited-clearance assembly. Used on engine accessory mounting and structural attach lugs.
- NAS 6603 (12-point) vs MS 21250 (12-point) — NAS 6603 and MS 21250 cover similar 12-point bolt geometry but with slightly different thread tolerance and material spec — NAS 6603 is current; MS 21250 is older MIL spec, now largely superseded.
A286 NAS Bolt Sizes & Spec Reference
| NAS part number | Size | Thread | Drive | Head ⌀ | Min. tensile (lbf) |
|---|---|---|---|---|---|
| NAS 1351-N3 | #10 (5 mm) | 32 UNF | Hex socket 5/32 | 0.250 inch | 1,800 |
| NAS 1351-N4 | 1/4 (6 mm) | 28 UNF | Hex socket 3/16 | 0.375 inch | 3,200 |
| NAS 1351-N6 | 3/8 (10 mm) | 24 UNF | Hex socket 5/16 | 0.5625 inch | 8,000 |
| NAS 6603-12 | 3/16 (4.8 mm) | 24 UNF | 12-point | 0.281 inch | 2,500 |
| NAS 6604-16 | 1/4 (6 mm) | 28 UNF | 12-point | 0.375 inch | 4,800 |
| NAS 6608-32 | 1/2 (13 mm) | 20 UNF | 12-point | 0.812 inch | 16,000 |
| NAS 6610-40 | 5/8 (16 mm) | 18 UNF | 12-point | 1.000 inch | 23,500 |
| NAS 6612-48 | 3/4 (19 mm) | 16 UNF | 12-point | 1.125 inch | 34,000 |
A286 NAS Bolts Manufacturing Process
Every a286 nas bolts TorqBolt ships traces back to a vacuum-induction-melted plus vacuum-arc-remelted (VIM-VAR) ingot meeting AMS 5731 / 5732 chemistry. The complete process route:
- VIM-VAR melt sourcing: Bar to AMS 5731 / 5732 from approved aerospace mills — ATI A286, Carpenter Pyromet A286, Special Metals Incoloy A286. Qualified per AS9100D.
- Aerospace bar prep: Bar surface inspected per ASTM E45 inclusion rating + 100 % LPI prior to manufacturing release.
- Cold heading (sizes ≤ M16): Aerospace cold-heading press — vacuum-degassed bar input, multi-station head + cone + drive form in single cycle.
- 5-axis CNC machining (M20+): Larger NAS bolts machined from solid bar — 12-point bi-hex geometry cannot be cold-headed at large size.
- Thread rolling MIL-S-8879 Class 3: Roll-formed threads to MIL-S-8879 / ASME B1.13M Class 3A tolerance — tighter than commercial 2A, required for aerospace fatigue.
- Vacuum solution treatment: Vacuum heat-treat 1650 °F (899 °C) per AMS 5737 / ASTM A453 Class A — vacuum environment prevents IGA / oxide contamination.
- Precipitation aging: 1325 °F (718 °C) for 16 hours, air-cool. Aerospace lots receive +/- 5 °C control on aging temperature for hardness consistency.
- Passivation + magnetic permeability check: Pickle / passivate per ASTM A967 Type II + permeability < 1.005 verified per ASTM A342 on every coil.
- AS9102 first-article + lot serialization: First-article on every new drawing or revision per AS9102; lots serialized 1-N for traceability per BAC 5004 / NAS 100.
A286 NAS Bolts Inspection & Certification
Each lot ships with a signed inspection certificate. Aerospace orders are released with AS9102 first-article inspection per AS9100D AQMS. Industrial orders default to EN 10204 type 3.1; sour-service and offshore step up to type 3.2 with third-party witness.
- 100 % thread-gauge GO/NO-GO per MIL-S-8879 Class 3 (tighter than commercial 2A).
- 100 % hex socket dimension check per NAS 1351 / ISO 2936 for SHCS variants.
- 100 % 12-point geometry check per NAS 6603 for 12-point bolts.
- Hardness traverse 4-point Vickers per heat-treat batch — ASTM E384 with NIST-traceable master.
- Magnetic permeability < 1.005 per ASTM A342 on every aerospace coil.
- LPI per ASTM E1417 Class 1 sensitivity on every NAS lot.
- Tensile coupon from each heat per ASTM E8 + elevated-temperature tensile per ASTM E21.
- AS9102 first-article inspection on every new drawing/revision per AS9100D AQMS.
- Salt-spray ASTM B117 96-hour pass per ASTM A967.
- Lot serialization 1-N for full traceability per BAC 5004 / NAS 100.
A286 NAS Bolts Torque & Assembly Practice
NAS A286 bolts torque per the airframe or engine assembly manual (Boeing 737 SOPM, GE Aviation engine manual, etc.) — never use commercial DIN / SAE J429 tables. MIL-HDBK-60 provides default aerospace torque values when assembly manual is absent. Aerospace OEMs (Boeing, Airbus, GE, P&W) typically mandate single-cycle replacement of NAS bolts on primary structure — re-use only on secondary structure with documented torque history. Above 540 °C apply nickel anti-seize per AS5272 to threads. Aerospace torque is typically 60-65 % of room-temperature yield for cycling joints, 70-75 % for static.
A286 NAS Bolt Applications by Industry
NAS A286 bolts dominate US-spec aerospace and defence assemblies:
- Jet-engine compressor: NAS 6603-6620 12-point CRES A286 bolts on compressor disc-to-disc retention and stator-vane attachment. The recurring Tier 1 OEM standard. A286 jet engine fasteners.
- Jet-engine turbine: NAS 6610-6620 on turbine wheel-to-shaft and inducer attach. 540-700 °C cyclic service.
- Aerospace structure: NAS 1351 / 6203 SHCS on Boeing 737-787, F-15, F-16, F-22, F-35 wing-spar internal bolting and engine-mount lugs.
- Defence helicopter: AH-64 Apache, UH-60 Black Hawk, V-22 Osprey use NAS 1351 / 6603 A286 bolts on rotor head, transmission, and engine mounts.
- Space launch: NAS A286 bolts on SpaceX Falcon 9, Blue Origin New Glenn, ULA Atlas / Vulcan upper-stage and engine assemblies — 700 °C ceiling + non-magnetic + cryogenic.
- Naval gas turbine (LM2500 / LM6000): NAS 6603 12-point on naval LM2500 / LM6000 hot-section bolting where salt-fog corrosion + 700 °C combine.
Governing Standards & Material Specifications
Every A286 fastener is released against the applicable industry standard. EN 10204 type 3.1 mill certificates ship with every order. See the consolidated A286 AMS / ASTM specifications hub for full spec scope.
| Authority | Specification | Coverage |
|---|---|---|
| ASTM | A453 grade 660 Cl. A/B/C/D | High-temperature bolting material |
| ASTM | A638 grade 660 Type 1/2 | Forged bolting stock |
| AMS | 5731 | Bar / forging — solution-treated |
| AMS | 5732 | Bar / forging — solution-treated and aged |
| AMS | 5737 | Bar — solution-treated and aged (precision) |
| UNS | S66286 | Material designation |
| DIN | 1.4980 / X5NiCrTiMoVB25-15-2 | European designation |
| EN | 10204 3.1 / 3.2 | Mill / third-party-witness certification |
| NACE | MR0175 / ISO 15156-3 | Sour-service hardness limit ≤ HRC 35 |
A286 NAS Bolts vs Alternative Materials
When selecting a fastener material engineers compare A286 against three alternatives: A286 vs Inconel 718 (top-end performance, 3× cost), A286 vs 17-4 PH (cheaper but limited to 315 °C), and A286 vs Waspaloy (sustained service > 700 °C). A286 is the cost-performance leader for non-magnetic precipitation-hardening service in the 540-700 °C envelope. See the consolidated A286 equivalent grades reference for full alloy alternatives.
How to Specify A286 NAS Bolts
A complete a286 nas bolts callout should include: material spec, heat-treatment condition, dimensional standard, size, thread tolerance class, surface finish, marking, inspection certificate. Example callout:
NAS 1351-N6, A286 (UNS S66286), ASTM A453 grade 660 Class A, ST+A, 3/8-24 UNF × 1.50 inch length, MIL-S-8879 Class 3 thread, magnetic permeability < 1.005, passivated per A967, head-stamped ‘NAS 1351-N6’ + ‘A286’ + lot + ‘TB’, AS9102 first-article on lot, lot serialized 1-N per BAC 5004.
A286 NAS Bolts — Frequently Asked Questions
What does NAS stand for in NAS bolts?
NAS = National Aerospace Standard, a series of dimensional and material specifications published by AIA (Aerospace Industries Association of America). NAS bolts are the dominant precision-hardening fastener on US-built aerospace assemblies.
What's the difference between NAS 1351 and NAS 6603 A286 bolts?
NAS 1351 = socket head cap screw (SHCS) with internal hex drive and cylindrical head. NAS 6603 = 12-point (bi-hex) flange bolt with external 12-point drive and lower-profile head. NAS 1351 used for compact joints; NAS 6603 used for high-torque jet-engine compressor and turbine bolting.
Are all NAS A286 bolts magnetic-permeability < 1.005?
Yes — NAS standards require magnetic permeability < 1.005 verified per ASTM A342 on every aerospace coil. This is preserved through cold heading, thread rolling, and aging. Critical for nav-system and proximity-sensor isolation.
What head marking is on a NAS A286 bolt?
Per the applicable NAS standard: head-stamped NAS part number (e.g. 'NAS 1351-N6') + 'A286' material + lot number + manufacturer code 'TB'. Stamp depth 0.05-0.10 mm raised or recessed per drawing.
Can NAS A286 bolts replace MS A286 bolts?
Generally yes for the same form-fit-function, but specific drawing call-outs must be checked. NAS standards are the current AIA-issued standard; MS standards are older MIL specs, many superseded by NAS. Always verify with cognisant engineering authority before substitution.
What thread tolerance applies to NAS A286 bolts?
MIL-S-8879 / ASME B1.13M Class 3A (inch) — tighter than commercial 2A. Required for aerospace fatigue performance per NAS 1351 / 6603 acceptance criteria.
Are NAS A286 bolts AS9100D-certified?
TorqBolt's AS9100D AQMS is current; AS9102 first-article inspection performed on every NAS A286 lot, and lot serialization 1-N maintained per BAC 5004 / NAS 100. Customer source-surveillance witnesses welcomed; recent witnesses include Tier 1 jet-engine OEM and US defence integrator audit teams.
Can NAS A286 bolts be re-used after disassembly?
Aerospace primary structure (engine mount, wing spar, fuselage frame, compressor disc): NO — single-use only per OEM SRM. Secondary structure with documented torque history: yes, with thread-distortion and head-stamp inspection per NAS 100.
What's the difference between NAS 6603 and NAS 6403?
NAS 6603 = standard 12-point bolt; NAS 6403 = 12-point bolt with reduced underhead transition (improved fatigue performance for high-cycle joints). Material identical (A286 / UNS S66286 per AMS 5732). Choose 6403 for cycling joints, 6603 for static.
Why TorqBolt for A286 NAS Bolts
Three reasons aerospace and gas-turbine OEMs place a286 nas bolts orders with us:
- Vertically integrated supply — VIM-VAR melt sourcing from approved AMS-conforming mills, in-house cold heading + thread rolling + vacuum heat-treatment.
- Aerospace AQMS — AS9100D-certified factory in Mumbai with published quality manual covering A286 fastener-specific failure-mode analysis.
- Lead time discipline — 4-6 weeks for ASTM A453 grade 660 standard sizes, 8-12 weeks for custom-drawing aerospace parts.
Three decades of fastener manufacturing experience; current certifications: ISO 9001:2015, AS9100D, PED 2014/68/EU, NORSOK M-650 QTR.
Recent A286 NAS Bolts Order Patterns
Recurring NAS A286 bolt orders: NAS 6610-6620 12-point compressor-disc retention, NAS 1351-N4 to N8 SHCS on aerospace accessory gearboxes, NAS 6603-12 to 6604-16 12-point on fighter-jet turbine bolting, and NAS 6612 12-point on helicopter transmission. All shipped with AS9102 first-article + matched-pair lot serialization per BAC 5004.
Satisfaction Survey
