AN960-516 - Premium Precision Aerospace Flat Washer

AN960-516 – NASM960 Cadmium-Plated Steel Flat Washer (5/16 Inch)

Available now on the Airparts.aero Marketplace.

The AN960-516 is the definitive, military-specification flat washer engineered for 5/16-inch diameter bolts and screws in critical aerospace applications. Manufactured to the exacting requirements of the NASM960 standard (which supersedes AN960), this component is far more than a simple spacer. It is a precision-engineered bearing surface designed to distribute fastener clamping force over a wider area, preventing damage to softer structural materials like aluminum alloys and composites. Its primary function is to ensure that the specified torque applied to a fastener translates into the correct, uniform preload, which is fundamental to the structural integrity and fatigue life of a bolted joint.

Constructed from high-quality carbon steel and protected by a sacrificial cadmium plating, the AN960-516 provides the necessary compressive strength and corrosion resistance required for the demanding flight environment. The washer's dimensional stability and surface hardness prevent galling and provide a smooth, low-friction surface for the turning nut or bolt head, eliminating the "stick-slip" effect that can lead to inaccurate preload. For A&P/IA mechanics and aerospace engineers, the AN960-516 is the trusted, traceable standard for all 5/16" fastener installations.

Key Features

• NASM960 Certified: Manufactured and inspected to the rigorous National Aerospace Standard, ensuring full traceability and airworthiness.

• High-Strength Steel Construction: Made from carbon steel to withstand high compressive loads without deformation, ensuring consistent clamp force.

• Superior Corrosion Resistance: Protected by a uniform cadmium plating (per QQ-P-416) that provides a sacrificial barrier against galvanic corrosion, especially between steel fasteners and aluminum structure.

• Precision Dimensions: Manufactured to tight tolerances for inside diameter, outside diameter, and thickness, guaranteeing a proper fit and consistent performance.

• Optimized Bearing Surface: Provides a smooth, hard surface that prevents damage to the airframe and ensures accurate torque-to-preload conversion.

Technical Specifications

• Part Number: AN960-516

• Alternate Part Numbers / Specifications: NASM960-516, MS15795-516

• Component Type: Flat Washer

• Material: Carbon Steel

• Finish: Cadmium Plate per QQ-P-416, Type II, Class 3 (Yellow Chromate)

• Nominal Size: 5/16 Inch

• Inside Diameter (ID): 0.344 inches

• Outside Diameter (OD): 0.625 inches

• Thickness: 0.063 inches

• Governing Specification: NASM960 (Supersedes AN960)

Aircraft Compatibility

The AN960-516 washer is a universally specified component used in tens of thousands of applications across the entire spectrum of aviation.

• Applicability: Used in virtually all certified aircraft, including general aviation (Cessna, Piper, Beechcraft), commercial transport (Boeing, Airbus), rotorcraft, and military airframes. Its use is dictated by the specific fastener joint design.

Note: The aircraft's specific Illustrated Parts Catalog (IPC) or maintenance manual is the sole authoritative document for verifying part number applicability for any given fastener location.

Applications

The AN960-516 is the standard washer for use with 5/16" diameter aerospace bolts (e.g., AN5) and screws.

• Primary Use: Installed under the nut and/or the bolt head in structural and non-structural joints to distribute load, span oversized holes, and protect the component surface. It is a required component in most standard torque applications.

Why Choose the Certified AN960-516?

A fastener joint is a complete system, and the washer is a critical element. Using an uncertified, generic hardware store washer introduces dangerous, unknown variables. These parts lack traceability and may be made from incorrect materials with improper hardness, leading to crushing or deformation under load. They often have inconsistent dimensions and lack the specific cadmium plating required to prevent galvanic corrosion, which can compromise the structural integrity of the airframe over time. Sourcing a fully certified and traceable AN960-516 is the only way to guarantee the safety, airworthiness, and long-term reliability of a bolted assembly.

The engineering function of the AN960-516 washer extends beyond simple load distribution; it is critical for managing preload scatter in a fastener stack-up. When torque is applied, the washer's uniform thickness and specified hardness (as dictated by NASM960) provide a consistent frictional interface and prevent localized yielding of the softer substrate material (e.g., 2024-T3 aluminum). This ensures a linear relationship between applied torque and resulting clamp force (preload). From a materials science perspective, its cadmium plating is specifically chosen for its position in the galvanic series relative to steel and aluminum. The cadmium (anodic to steel but typically cathodic or neutral to aluminum in many environments) preferentially corrodes, acting as a sacrificial anode that protects the more noble steel fastener while minimizing the galvanic potential that could cause rapid corrosion of the aluminum airframe structure, a phenomenon that would otherwise occur at the steel-aluminum interface.

Note: The AN960-516 is an essential component of a flight-critical fastener assembly. Always use the correct washer as specified by the maintenance manual. Inspect washers for damage, corrosion, or deformation before installation and discard if any defects are found. Installation must be performed by a certified technician, and the corresponding nut or bolt must be tightened to the correct torque value as specified in the applicable structural repair or maintenance manual.

Documentation

The governing standard NASM960 is a controlled document. However, public-domain reference charts detailing the dimensional and material standards for all AN960 / NASM960 series washers are widely available from aerospace hardware suppliers and in standard reference texts like AC 43.13-1B.

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 40
7. •Bombardier Learjet 45
8. •Bombardier Learjet 55
9. •Bombardier Learjet 60 - all variants
10. •Dassault Falcon 2000 all variants
11. •Dassault Falcon 7X
12. •Dassault Falcon 900 all variants
13. •Embraer Legacy 600-650
14. •Embraer Phenom 300
15. •Gulfstream G-IV/GIV-SP/G-400/G-450/G-300
16. •Gulfstream G-V/G-V-SP/G-550/G-500
17. •Pilatus PC-12
18. •Piper Aircraft PA-42 Cheyenne
19. •Textron Aviation Beechcraft King Air 100 - all variants
20. •Textron Aviation Beechcraft King Air 200 - all variants
21. •Textron Aviation Beechcraft King Air 300 - all variants
22. •Textron Aviation Beechcraft King Air 90 - all variants
23. •Textron Aviation Beechcraft Premier
24. •Textron Aviation Bell 206 Jetranger/Longranger
25. •Textron Aviation Cessna 500 Citation I-ISP
26. •Textron Aviation Cessna 510 Citation Mustang
27. •Textron Aviation Cessna 525 Citation Citationjet
28. •Textron Aviation Cessna 550 Citation I-II-Bravo
29. •Textron Aviation Cessna 560 Citation V-Ultra-Encore-Excel-XLS
30. •Textron Aviation Cessna 650 Citation III-IV-VI-VII
31. •Textron Aviation Cessna 680 Citation Sovereign
32. •Textron Aviation Cessna 750 Citation X
33. •Textron Aviation Hawker 400-400XP
34. •Textron Aviation Hawker 800
35. •Textron Aviation Hawker 800XP-850XP
36. •Textron Aviation Hawker 900XP

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