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A286 Jet Engine Fasteners — Compressor, Turbine, Casing Bolting

Q: What's the most common A286 fastener in jet engines?

NAS 6603-6620 12-point CRES A286 bolts on compressor disc-to-disc retention. M16-M24 / 5/8-1 inch sizes are the highest-volume aerospace A286 fasteners — used on virtually every modern commercial and military jet engine.

Q: Why A286 instead of Inconel 718 for jet-engine bolting?

Cost — A286 is one-third the price. For service ≤ 700 °C, A286 meets the same temperature ceiling. Inconel 718 reserved for highest-strength applications where 130 ksi tensile insufficient. See A286 vs Inconel 718.

Q: Can A286 bolts be used in the high-pressure turbine?

Up to ~700 °C continuous service — yes. For stage 2-3 high-pressure turbine where temperature reaches 750-870 °C, Waspaloy or single-crystal nickel-base alloys are required. A286 used in stages 1-2 and accessory hardware.

Q: What aerospace QA requirements apply to A286 jet-engine fasteners?

AS9100D Aerospace Quality Management System with AS9102 first-article inspection on every new drawing/revision. Lot serialization 1-N per BAC 5004 / NAS 100. EN 10204 type 3.1 mill cert standard; type 3.2 third-party witness for safety-critical lots. Magnetic permeability < 1.005 verified per ASTM A342 on every coil.

Q: Are A286 jet-engine fasteners single-use?

Aerospace primary structure (compressor disc bolts, turbine attach bolts): NO — single-use only per OEM SRM. Aerospace secondary / accessory mounting: yes with thread-distortion and head-stamp inspection. Replace bolts at OEM-mandated service intervals (typically every C-check, ~6000 flight hours).

Q: What head-stamp on A286 jet-engine bolts?

Per the applicable NAS / MS standard: head-stamped NAS / MS part number + 'A286' material + lot number + manufacturer code 'TB'. Stamp depth 0.05-0.10 mm raised or recessed per drawing.

Q: Can A286 bolts be re-used after engine teardown?

Aerospace primary structure (compressor disc, turbine wheel-to-shaft): NO — single-use only. Aerospace secondary (accessory mounting, casing-split): yes with thread-distortion and head-stamp inspection. ALL aerospace bolts must be inspected per OEM SRM before re-use.

Q: What's the lead time on AMS 5732 NAS 6603 12-point bolts?

Standard sizes M10-M24 / 3/8-1 inch: 8-12 weeks from heat release. Larger sizes M30-M48: 12-16 weeks. Aerospace AS9102 first-article + EN 10204 3.2: add 2-3 weeks.

Q: Do A286 jet-engine fasteners need anti-galling lubricant?

Above 540 °C service: YES — apply nickel or silver anti-seize per AS5272 to thread surfaces only. Below 540 °C: optional, depending on OEM specification. Without anti-seize, A286 austenitic threads gall against austenitic-stainless mating threads above 540 °C.

A286 jet engine fasteners are the dominant precipitation-hardening superalloy bolts and screws used throughout modern jet engines — from low-pressure compressor casing-split bolts to high-pressure turbine wheel attach hardware. TorqBolt manufactures every common A286 jet-engine fastener configuration to NAS 1351 / NAS 6203 (socket head cap screws), NAS 6603-6620 (12-point bi-hex bolts), MS 90725 / MS 90726 (hex bolts), BACB30NW / BACB30LE (Boeing-spec), and AS3239 / IFI-115 (12-point flange) standards. Heat-treated to ASTM A453 grade 660 Class A from AMS 5731 / 5732 / 5737 bar — 130 ksi tensile / 95 ksi yield, retained preload to 700 °C, magnetic permeability < 1.005. AS9100D AQMS with AS9102 first-article inspection on every drawing/revision. See parent A286 stainless steel, related variants A286 bolts, CRES bolts, NAS bolts, hex bolts, socket head cap screws, sister applications gas turbine, aerospace, nuclear.

Why A286 for This Application

A286 jet engine fasteners — compressor disc bolting NAS 6603 12-point

Modern commercial jet engines (CFM56, GE90, GEnx, Rolls-Royce Trent series, Pratt & Whitney PW1000G) have specific fastener material requirements driven by operating conditions: compressor section operating temperatures 400-540 °C; turbine section 540-700 °C; cyclic service from start-up to full power with 2000-5000 cycles between major overhauls. A286's combination of cost-efficiency (one-third the cost of Inconel 718), retained preload to 700 °C, non-magnetic behaviour (compatible with magnetic flux gauges and sensors), cryogenic toughness (LNG fuel pump applications), and NACE MR0175 sour-service compliance (some engine fuel-system bolts) makes A286 the dominant aerospace fastener material globally. See A286 vs Inconel 718 for the cost-performance comparison.

A286 Components Used in This Application

Compressor disc-to-disc bolting: NAS 6603-6620 12-point CRES A286 bolts hold compressor discs together — typical M16-M24 / 5/8-1 inch sizes, matched-pair lots, AS9102 first-article on every new drawing. Compressor stages 1-5 use A286 NAS 6603 12-point as the dominant choice.
Turbine wheel-to-shaft attach: NAS 6610-6620 12-point bolts on turbine wheel attachment to compressor shaft. Operating temp 540-700 °C — at the upper limit of A286 capability. For higher-temperature turbine stages 2-3, Inconel 718 used.
Casing-split flange bolting: Hex bolts (DIN 933 / MS 90725 / NAS 1303) on engine compressor and turbine casing-split flanges. M12-M30 sizes typical. Spiral-wound gaskets between flange faces.
Augmentor case bolting: NAS 1351 SHCS on military-spec engine augmentor (afterburner) casing — operating temp 700-820 °C. A286 used on cooler portions; Waspaloy or single-crystal alloys for hot-side.
Accessory gearbox attach: NAS 1351 / NAS 6203 SHCS attach the accessory gearbox to engine main casing. Hosts fuel pump, oil pump, alternator, hydraulic pump, vacuum pump.
Fuel-system manifold bolting: BACB30NW / BACB30LE Boeing-spec bolts on fuel manifold attach. Wet-fuel-side environment requires NACE MR0175 hardness verification (≤ HRC 35) for corrosion resistance.
Bearing housing retention: SHCS NAS 1351 retain main-bearing housings inside compressor and turbine sections. Magnetic permeability < 1.005 critical to prevent magnetic-flux interference with engine speed sensors.
Combustor liner attachment: NAS 1351 SHCS attach combustor liner to outer casing. Operating temp 700-1000 °C; A286 acceptable on cooler portions but Hastelloy X / Inconel 625 for hot-side.

Governing Standards & Specifications

NAS 1351 / NAS 1352 (socket head cap screws) — Aerospace SHCS — internal hex drive, MIL-S-8879 thread, magnetic permeability < 1.005.
NAS 6603-6620 (12-point bi-hex bolts) — 12-point external drive for high-torque compressor / turbine bolting. Standard for primary structural attach.
NAS 1303-1320 (short-form aerospace hex bolts) — Short-form internal-wrenching designs for limited-clearance engine assembly.
MS 90725 / 90726 (hex bolt MIL-spec) — MIL-spec hex bolts on US military aerospace structure where MS-spec is invoked.
BACB30NW / BACB30LE (Boeing internal-spec) — Boeing CRES bolt patterns for 737-787 maintenance, overhaul, and re-engineering.
AS3239 / IFI-115 (12-point flange) — Aerospace 12-point flange bolt — high-torque transmission with reduced under-head height.
AS9100D AQMS — Aerospace Quality Management System requirement — applies to all jet-engine fastener manufacture.
AS9102 first-article inspection — Required on first part of any new drawing or revision for AS9100D AQMS lots.

Manufacturing & Quality Process

VIM-VAR melt sourcing: Bar to AMS 5731 / 5732 chemistry from approved aerospace mills — ATI A286, Carpenter Pyromet A286, Special Metals Incoloy A286.
Aerospace cold heading: Vacuum-degassed bar input. Multi-station cold-heading press forms head + cone + drive geometry in one cycle. Aerospace lots run with closed-loop force monitoring.
Thread rolling MIL-S-8879: Roll-formed threads to MIL-S-8879 / ASME B1.13M Class 3A tolerance — required for aerospace fatigue performance.
Vacuum solution treatment: 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 ±5 °C control for hardness consistency. Hardness 277-302 HBW (29-32 HRC).
Magnetic permeability + LPI inspection: 100 % magnetic permeability check < 1.005 per ASTM A342 + LPI per ASTM E1417 Class 1 sensitivity.
AS9102 first-article + lot serialization: First-article on every new drawing / revision per AS9100D; lot serialization 1-N per BAC 5004 / NAS 100.
Passivation per ASTM A967: Type II passivation. Optional silver / nickel anti-galling coat on threads for above-540 °C service per AS5272.

Material Selection by Service Condition

Operating temperature 400-540 °C: A286 dominant — cost-efficient at one-third Inconel 718. Use A286 NAS 6603 12-point bolts for compressor discs, NAS 1351 SHCS for casing.
Operating temperature 540-700 °C: A286 acceptable but at upper limit. For high-stress applications Inconel 718 specified by OEM. See A286 vs Inconel 718.
Operating temperature 700-870 °C: Waspaloy required — A286 cannot maintain strength. See A286 vs Waspaloy.
Cryogenic LNG-engine fuel pump bolts: A286 retains 85 % toughness at -196 °C. Standard for LNG-engine bolted hardware.
Non-magnetic instrumentation bolts: A286 NAS 1351 SHCS — permeability < 1.005. Critical near magnetic-flux sensors and speed gauges.
NACE MR0175 sour-service (engine fuel system): A286 grade 660 with ≤ HRC 35 hardness for fuel-system bolts exposed to sour gas content. Specify on PO.