NAS1149F0663P - Textron Aviation OEM Flat Washer

NAS1149F0663P – Textron Aviation OEM 3/8" CRES Flat Washer (.063" Thick)

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Overview

The NAS1149F0663P is a precision-manufactured, standard-thickness flat washer that holds dual certification: it is produced to the rigorous National Aerospace Standard (NAS1149) and is supplied as a genuine Textron Aviation Original Equipment Manufacturer (OEM) component. This washer is fabricated from high-quality Corrosion Resistant Steel (CRES), making it the ideal choice for use with stainless steel fasteners to prevent galvanic corrosion and for installations in harsh environments.

While seemingly simple, a certified washer is a critical component in any bolted joint. Its primary engineering functions are to distribute the high compressive load of a torqued fastener over a wider surface area to prevent damage to the structure, and to provide a smooth, hard bearing surface for the nut or bolt head. This ensures that applied torque is converted into consistent and accurate bolt preload (clamping force). As a Textron Aviation OEM part, this washer is the factory-specified component for countless applications across their aircraft fleets.

Key Features

• Textron Aviation OEM Certified: Supplied with the full traceability and quality assurance of Textron Aviation, guaranteeing it is the correct part for their fleet of Cessna, Beechcraft, and Hawker aircraft.

• Corrosion Resistant Steel (CRES): Fabricated from a 300-series stainless steel alloy, offering superior resistance to rust, oxidation, and environmental corrosion.

• Passivated Finish: The CRES material is passivated per aerospace standards, creating a passive oxide layer that enhances its natural corrosion resistance.

• Load Distributing Design: Prevents galling, marring, and crushing of softer structural materials (like aluminum alloy) under the high pressure of a bolt head or nut.

• Standard Thickness: A "-63" designation indicates a nominal thickness of 0.063 inches, the standard-duty washer for a 3/8-inch bolt.

• NAS Standard Compliance: Guarantees adherence to precise dimensional tolerances, material chemistry, and quality required for airworthy hardware.

Technical Specifications

• Part Number: NAS1149F0663P

• Component Type: Flat Washer

• OEM Authority: Textron Aviation

• Governing Specification: NAS1149 (supersedes AN960)

• Material: Corrosion Resistant Steel (CRES), 300-Series

• Finish: Passivated per AMS-QQ-P-35

• Intended Bolt/Screw Size: 3/8 inch

• Inside Diameter (ID): 0.406 inches

• Outside Diameter (OD): 0.812 inches

• Nominal Thickness: 0.063 inches

Aircraft Compatibility

As a Textron Aviation OEM part and a NAS standard, this washer is used ubiquitously across their entire product line and the aerospace industry at large.

• Primary Textron Aviation Platforms:

  • Cessna Citation Series Business Jets

  • Beechcraft King Air, Baron, and Bonanza

  • Cessna Caravan and Piston Aircraft

  • Hawker Business Jets

• General Aerospace Usage: Used under nuts and bolt heads in airframe, powerplant, landing gear, and systems installations on virtually all certified aircraft.

Note: Verification of applicability is the responsibility of the installer. Always consult the current version of the aircraft's Illustrated Parts Catalog (IPC) and maintenance manual to confirm part number eligibility.

Applications

• To provide a smooth bearing surface for accurate torque application.

• To distribute fastener clamp load and protect structural surfaces.

• For use as a shim to adjust the grip length of a bolt in some applications.

• To prevent galvanic corrosion when used with CRES bolts on dissimilar metals.

Why Choose NAS1149F0663P?

The performance of a bolted joint is only as good as its weakest component. Using a certified NAS1149 washer is critical to ensuring the joint achieves the proper preload and maintains it in service. A non-certified washer may be made of an incorrect or softer material, causing it to yield or deform under load, leading to a loss of preload and potential joint failure. Sourcing this as a Textron Aviation OEM part provides the ultimate assurance that you are installing the exact component specified and certified for the aircraft.

A certified washer like the NAS1149F0663P plays a critical tribological role in achieving the correct bolt preload, which is the single most important factor in the success of a structural bolted joint. A significant percentage of the energy from applied torque (up to 50%) is consumed by friction between the turning nut or bolt head and the stationary bearing surface. The hard, smooth, and chemically passive surface of this passivated CRES washer provides a consistent and predictable coefficient of friction. This consistency is vital, as it ensures that the torque values specified in the maintenance manual are reliably converted into the intended axial bolt tension (preload). Using a washer with a different material or finish, or no washer at all, introduces a highly variable coefficient of friction, which can lead to a dangerously under-loaded (insufficient clamp) or over-loaded (yielded bolt) joint, even when using a calibrated torque wrench.

Note: This is a flight-critical hardware component. It is an integral part of the fastener assembly. Washers should be clean and free of burrs or damage before installation. When a washer is called for in the maintenance manual, it must not be omitted. Always use the correct size and material specified for the joint.

Documentation

The base standard for this part is the National Aerospace Standard NAS1149. This is a controlled document managed by the Aerospace Industries Association (AIA). OEM-specific application data is contained within the Textron Aviation maintenance and parts manuals.