AN960-916L - Flat Carbon Steel Aerospace Washer Overall Diameter 1.057 Inches

AN960-916L – Aeronautical Standards Group Flat Aerospace Washer (Light Series)

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The AN960-916L is a high-reliability, flight-certified structural flat washer manufactured in strict compliance with Aeronautical Standard Group parameters and the legacy MIL-W-5083 military standard specifications. Featuring a nominal hole size of 9/16 inches ($0.5625\text{ in}$) and a precision-ground overall outside diameter of 1.057 inches ($1.062\text{ in}$ nominal), this high-density hardware component is explicitly engineered for integration beneath the nuts and bolt heads of primary airframe joints, landing gear attach points, and high-load engine mounts. The "L" suffix designates the "Light" series variant, which features a reduced thickness profile compared to standard AN960 washers, optimizing weight and providing precise stack-up height control in tight structural clearances.

Fabricated from high-grade, carbon structural steel or low-alloy steel matrix, the AN960-916L undergoes precision stamping and flattening operations to eliminate microscopic surface burrs and dimensional warping. The washer is finished with an electro-deposited cadmium plating (QQ-P-416 Type II, Class 2 or equivalent) topped with a gold chromate conversion strike. This specialized surface engineering serves a critical dual purpose: it acts as a sacrificial corrosion barrier to prevent localized atmospheric oxidation, and it provides a smooth, low-coefficient boundary layer that prevents galvanic corrosion when a carbon steel bolt clamps tightly down on non-ferrous aluminum or magnesium airframe sheets.

The AN960-916L represents the industry baseline standard across general aviation fleets, commercial transport networks, and defense aerospace sustainment programs. By distributing the heavy compressive clamping preload of a torqued fastener over a wider structural surface area, it prevents the bolt head or nut from gouging or embedding into the softer airframe metals. For structural repair engineers, A&P mechanics, and aviation logistical buyers, deploying fully traceable AN960-916L hardware guarantees that structural repairs match original factory type-certificate limits, maintaining structural torque retention over extended cyclic operational profiles.

Key Features

• Optimized Light Series Thickness: Features a slim 0.032-inch profile designed for tight-clearance stack-ups, allowing precise control over bolt grip and thread extension limits.

• Symmetrical Clamping Distribution: Widens the compressive load footprint of 9/16-inch fasteners, effectively preventing surface marring, embedding, and stress concentration cracking.

• Sacrificial Cadmium/Chromate Surface: Plated per QQ-P-416 parameters to maximize protection against environmental oxidation and galvanic breakdown when connecting dissimilar metals.

• Precision Defect-Free Edge Stamping: Manufactured under rigid quality parameters to ensure perfect flatness and concentricity, eliminating edge burrs that could score airframe skin.

• Genuine Airframe Structural Baseline: Matches open military standard and NASM960 hardware configurations, dropping cleanly into pre-certified standard structural repair configurations.

Technical Specifications

• Part Number: AN960-916L (Cross-Reference: NASM960-916L, MS27183 series matching metrics)

• Component Type: Flat Airframe Structural Washer (Light/Thin Series)

• Governing Specification: AN960 Standard / MIL-W-5083 (Superseded by NASM960)

• Nominal Screw/Bolt Size Matching: 9/16 Inch ($0.5625\text{ in}$)

• Inside Diameter (I.D.): 0.578 Inches nominal ($0.578\text{ in}\ \pm 0.005\text{ in}$)

• Outside Diameter (O.D.): 1.057 Inches nominal ($1.057\text{ in}$ to $1.062\text{ in}$ operational envelope)

• Nominal Thickness: 0.032 Inches ($1/32\text{ in}$ Thin / Light classification limit)

• Material Composition: Medium Carbon Steel / High-Tensile Low-Alloy Structural Steel Matrix

• Finish Treatment: Cadmium Plated (QQ-P-416, Type II, Class 2) with Chromate Conversion Strike

• Hardness Rating: Standard structural airframe hardware baseline limits

• Certification Status: Certificate of Conformance (CoC) / Full Material Traceability Profile

Aircraft Compatibility

• General Aviation & Utility Transports: Cessna 185 Skywagon, 206 Stationair, 208 Caravan, 210 Centurion Series; Piper PA-31 Navajo, PA-42 Cheyenne Series; Beechcraft Bonanza, Baron, and King Air 90/200/300/350/360 Twin-Turboprop Series.

• Commercial Transport & Corporate Commuters: Embraer ERJ 135/145 regional fleets, Bombardier CRJ series, ATR 42/72 turboprops.

• Heavy Agricultural Powerplants: Air Tractor AT-502, AT-602, AT-802 Series; Thrush Aircraft S2R Series structural engine mounts and landing gear attach blocks.

• Note: Fastener and washer stack-up selection must be verified strictly by referencing the target aircraft's specific Illustrated Parts Catalog (IPC), Structural Repair Manual (SRM), or approved standard hardware indices.

Applications

• Primary Structural Clamping: Placed under 9/16" hex bolts and castle nuts on landing gear pivot brackets, wing attach fittings, and structural airframe torque tubes.

• Grip Length Fine-Tuning: Shimming structural joint spaces to achieve exact bolt-grip layout alignment, ensuring threads do not rest within a primary bearing shear plane.

Why Choose AN960-916L?

Selecting a trace-certified AN960-916L flat washer prevents joint relaxation and structural relaxation associated with unverified or commercial hardware store equivalents. Automotive or basic industrial washers lack the structural flatness tolerances, strict inner/outer concentricity limits, and certified cadmium thickness boundaries mandatory for aerospace flight applications. Commercial zinc-plated washers driven into an aircraft structure frequently cup or deform plastically under high installation torque loads, reducing initial clamp preload and forcing the joint to work loose under alternating aerodynamic vibrations. This degradation risks severe hardware fretting, bolt shearing, or hole ovalization. Sourcing fully traceable AN960 series parts guarantees uniform material stiffness, maintaining precise torque values and preserving structural airframe safety margins.

The performance mechanics of the AN960-916L washer focus on the principles of compressive stress distribution and frictional torque isolation within highly tensioned mechanical joints. When a 9/16" aerospace bolt is torqued, the localized clamp load creates a high axial force. If this load rests directly against soft non-ferrous metal, it causes the material to surpass its proportional limit, leading to brinelling or physical gouging. The AN960-916L resolves this by serving as a rigid, low-deflection plate that transfers the load across its 1.057-inch surface area footprint, keeping the bearing stress well within the safe elastic range of the surrounding structure.

Concurrently, during the torque application sequence, the cadmium plating functions as a solid-film lubricant that stabilizes the torque-to-tension relationship. This optimization prevents the rotating nut from galling or scuffing the airframe finish. The thin 0.032-inch geometry allows technicians to adjust the installation layout precisely. This ensures that the thread runout stays completely clear of the internal shear planes while maintaining the required one-to-three thread extension past the self-locking nut element.

Note: The AN960-916L is a structural, flight-governing hardware component. Utilizing corroded or cupped washers, stacking more than the maximum permitted number of washers (typically three per joint per FAA guidelines unless explicitly engineered otherwise), or using uncertified industrial hardware can lead to rapid loss of bolt preload, joint degradation, or catastrophic fastener failure. Fastener integration, structural shimming validation, and joint assembly inspection must be conducted exclusively by a certified A&P/IA mechanic in strict accordance with the aircraft Structural Repair Manual (SRM) and FAA Advisory Circular AC 43.13-1B Chapter 7. Always verify thread clearance limits before completing final torque specifications.

Documentation

• AIA/NAS NASM960 General Specification Sheet for Washers, Flat, Aircraft

• FAA Advisory Circular AC 43.13-1B: Acceptable Methods, Techniques, and Practices - Aircraft Inspection and Repair (Chapter 7: Aircraft Hardware)

• No direct standalone standalone OEM manufacturing blueprint PDF download is available for this generic military standard item sequence; precise dimensional limits should be checked using authorized standard military technical index layouts or a licensed Textron/AIA hardware reference publications chart.

Description:   WASHER
Part number:   AN960-916L
Alternate part number:   NAS1149F0932P
Industry Standard Specification:   AN960

Flat Washer - Size: 9/16", Thickness: 1/32", Carbon Steel, Cadmium Plated Finish


AN960-916L   FEATURES

This part is used on the following aircraft:

• 1. Bombardier Challenger 300
• 2. Bombardier Challenger 601
• 3. Bombardier Challenger 604
• 4. Bombardier Challenger 605
• 5. Bombardier Global Express
• 6. Bombardier Learjet 55
• 7. Bombardier Learjet 60 - all variants
• 8. Embraer EMB 505 Phenom 300
• 9. Textron Aviation Beechcraft King Air 100 - all variants
• 10. Textron Aviation Beechcraft King Air 200 - all variants
• 11. Textron Aviation Beechcraft King Air 300 - all variants
• 12. Textron Aviation Beechcraft King Air 90 - all variants
• 13. Textron Aviation Cessna 500 Citation I-ISP
• 14. Textron Aviation Cessna 525 Citation Citationjet
• 15. Textron Aviation Cessna 560 Citation V-Ultra-Encore-Excel-XLS
• 16. Textron Aviation Cessna 650 Citation III-IV-VI-VII
• 17. Textron Aviation Cessna 680 Citation Sovereign
• 18. Textron Aviation Cessna 750 Citation X
• 19. Textron Aviation Hawker 400-400XP
• 20. Textron Aviation Hawker 800XP-850XP

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