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A8K75 NAS1329A08K75 – Textron Aviation OEM Open Ended Keyed Rivnut
Available now on the Airparts.aero Marketplace.
Overview
The Textron Aviation specified NAS1329A08K75 is a flight-critical, keyed blind threaded insert, an essential piece of hardware for modern airframe assembly and repair. Often referred to by the shorthand A8K75 or generically as a Rivnut®, this is not a standard fastener. It is a sophisticated, permanently installed insert designed to provide high-strength, reusable threads in thin sheet metal or composite materials. The key feature of the NAS1329 series is the integrated "key" or lug, which mechanically locks the insert into the structure, providing exceptional resistance to spin-out under torque.
This component is fundamental for attaching interior panels, avionics racks, and systems hardware in areas where access to the backside is impossible. As a genuine OEM-specified part, it guarantees the certified material strength and precise dimensions required for a durable and airworthy structural attachment point.
Key Features
Keyed for Spin-Out Resistance: Features a "key" or "lug" on the body that fits into a corresponding notch in the installation hole. This mechanical lock provides significantly higher resistance to spinning compared to standard round-body inserts, a critical feature for serviceable components where screws are frequently removed and installed.
Provides Permanent, High-Strength Threads: Allows for the installation of durable, load-bearing #8-32 UNC-3B machine threads in materials that are too thin to be tapped directly. The internal threads conform to the highest aerospace tolerance class (3B) for a secure fit.
Blind Installation Capability: Engineered to be installed entirely from one side of the workpiece ("blind installation"). This makes it the ideal solution for adding threads to closed-out structures like fuselage frames, wing ribs, and assembled enclosures.
Lightweight Aluminum Alloy: The "A" in the part number specifies that it is manufactured from a high-strength, lightweight 2024-T4 aluminum alloy. This provides excellent performance without a significant weight penalty, a key consideration in aerospace design.
NAS Certified Standard: Manufactured in strict accordance with the NAS1329 standard, guaranteeing material composition, dimensional tolerances, and performance characteristics for certified aviation use.
Technical Specifications
Part Number: NAS1329A08K75
Component Type: Rivet, Blind, Threaded, Keyed, Open End
Material (A): 2024-T4 Aluminum Alloy
Finish: Anodized
Head Style: Flat Head
Thread Specification: #8-32 UNC-3B
Grip Range (K75): 0.051 to 0.100 inches (This is the material thickness range the insert is designed to be installed in).
Key Style: Single Key
Installation: Requires a specialized Rivnut installation tool with a #8-32 pull-up stud.
Aircraft Compatibility
The NAS1329A08K75 is a universal fastener used across all types of modern aircraft where strong, anti-rotation threaded inserts are required in thin materials. It is specified by Textron Aviation for numerous non-structural and secondary structural applications on their full line of aircraft.
Common Aircraft Platforms:
Textron Aviation (Cessna & Beechcraft): Citation series, King Air series, Caravan, piston fleet.
Common Applications:
Avionics Installation: Mounting avionics trays, shelves, and instruments to thin sheet metal panels.
Interior Completion: Securing interior panels, brackets, cabinetry, and furnishings.
Systems Installation: Providing threaded attachment points for hydraulic, fuel, and electrical line clamps (adel clamps).
Why Choose NAS1329A08K75?
A standard Rivnut can spin in its hole if the mating screw is over-torqued or becomes corroded, leading to a difficult and time-consuming repair. The keyed design of the NAS1329A08K75 mechanically prevents this failure mode, ensuring a reliable and serviceable threaded point for the life of the airframe. Using a certified NAS standard part guarantees that the fastener has the correct material strength, thread class, and dimensional tolerances required for a professional and airworthy installation.
The NAS1329A08K75 is installed through a process of controlled deformation. After being inserted into a pre-drilled and notched hole, a specialized tool engages the threads and exerts a powerful pulling force on the threaded mandrel. This axial force causes the unthreaded shank of the Rivnut to collapse and bulge outward on the blind side of the material, forming a secondary head. This bulge, or "upset," securely clamps the parent material between the Rivnut's flat head and this newly formed flange. The "key" provides the mechanical lock against rotation, while the upset provides the tensile strength, preventing the insert from being pulled out of the structure. The "grip range" is the most critical parameter for selection, as it must precisely match the thickness of the material to ensure the bulge forms correctly and creates a secure clamp.
Note: This is a structural fastener. Installation requires a pre-drilled round hole with a small, straight-sided notch to accommodate the key. The hole size must be precise. Always use the correct installation tool to ensure the Rivnut is properly set without being over-stressed. Do not exceed the specified grip range for the selected fastener.
