AN7-47A - Textron Aviation OEM Undrilled Shank Machine Bolt

AN7-47A – Textron Aviation Undrilled 7/16" Airframe Bolt

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The AN7-47A is a high-strength, structural airframe bolt manufactured in strict accordance with Army-Navy (AN) aerospace standards. While manufactured to a universal military specification, the AN7-47A is an OEM-specified bolt used by Textron Aviation in numerous high-strength structural applications on their Cessna and Beechcraft airframes. The AN7-47A is defined by its 7/16-inch diameter, 4-7/8-inch length, and the "A" suffix, which designates an undrilled shank for use with a self-locking nut.

Every aspect of this fastener, from its heat-treated alloy steel composition to its superior rolled-thread manufacturing process, is tightly controlled by the AN specification. This ensures a level of strength, fatigue resistance, and reliability that commercial-grade hardware cannot provide. This is not merely a bolt; it is a certified, traceable, and flight-critical structural component essential for airworthiness.

Key Features

• Army-Navy (AN) Specification Certified: Guarantees that the bolt meets the stringent material, manufacturing, and quality control requirements for certified aircraft use, as specified by OEMs like Textron Aviation.

• High-Strength Alloy Steel: Forged from high-grade alloy steel (typically SAE 4140 or 8740) and heat-treated to achieve a minimum tensile strength of 125,000 PSI.

• Undrilled Shank ('A' Designation): Specifically designed for use with self-locking nuts (e.g., nylon insert or all-metal locknuts), providing secure fastening in applications where cotter pins are not used.

• Rolled Threads for Superior Fatigue Resistance: Features UNF-3A threads that are cold-rolled, not cut, creating a continuous grain structure that dramatically increases resistance to fatigue failure from vibration and load cycling.

• Cadmium Plated for Corrosion Resistance: Coated with a sacrificial layer of cadmium per specification QQ-P-416, providing excellent corrosion protection.

Technical Specifications

• Part Number: AN7-47A

• Component Type: Undrilled Airframe Bolt

• Governing Specification: AN7

• OEM Applicability: Textron Aviation (Cessna, Beechcraft), among other major airframe manufacturers.

• Material: Heat-Treated Alloy Steel (e.g., SAE 4140 / 8740).

• Finish: Cadmium Plated per QQ-P-416, Type II, Class 3.

• Dimensions:

  • Shank Diameter: 7/16 inch (0.4375 in)

  • Overall Length (from under head to end): 4-7/8 inches (4.875 in)

  • Threads: 7/16-20 UNF-3A

  • Grip Length (unthreaded portion): 4-3/32 inches (4.094 in)

• Minimum Tensile Strength: 125,000 PSI

• Head Marking: Standard AN marking (cross or asterisk) for positive identification.

Aircraft Compatibility

The AN7-47A is a standard hardware component used across all categories of certified aircraft. It is specified in high-strength structural applications on numerous Textron Aviation airframes, from piston singles to corporate jets, wherever a bolt of this size and strength is required.

Crucial Note: The correct bolt part number, grip length, and required locking method for a specific application must be verified against the aircraft's Illustrated Parts Catalog (IPC) or maintenance manual.

Applications

The AN7-47A is designed for critical structural connections where a self-locking nut is the specified method of securing the fastener. Common applications include:

• Airframe Structural Assembly (wing-to-fuselage, spar attachments)

• Flight Control Surface Attachments

• Landing Gear Component Installation

• Engine Mounts and Pylon Structures

Why Choose AN7-47A?

Choosing a genuine, traceable AN7-47A bolt, as specified by OEMs like Textron Aviation, is a flight-critical decision. Commercial or industrial-grade bolts lack the mandatory material certifications, the superior fatigue life of rolled threads, the specified heat treatments, and the stringent quality control of AN-standard hardware. The failure of a single structural bolt due to material defects or fatigue can have catastrophic consequences. The "AN" designation is the guarantee of quality, ensuring that the fastener has been manufactured, tested, and inspected to the highest standards of the aerospace industry.

The profound fatigue resistance of the AN7-47A bolt is a direct result of its mandatory rolled thread manufacturing process. Unlike machine-cut threads, which sever the material's grain structure and create microscopic stress risers at the thread root, rolled threads are formed by a cold-working process. A precision-ground bolt blank is forced between hardened steel dies that plastically deform the surface, causing the material to flow into the shape of the thread root and crest. This cold-working process induces a state of compressive residual stress at the critical thread root area and creates a continuous, unbroken grain flow that follows the contour of the thread. This compressed, smoothly contoured grain structure is exceptionally resistant to the initiation and propagation of fatigue cracks. As a result, a bolt with rolled threads can exhibit a fatigue life that is 50-75% greater than that of a geometrically identical bolt with cut threads, a non-negotiable engineering requirement for fasteners subjected to the constant vibration and cyclic loading inherent in aircraft operations.

Note: This is a flight-critical structural fastener. CRITICAL: The 'A' suffix indicates an undrilled shank. This bolt MUST be secured with a self-locking nut (e.g., AN365, AN364) or other approved locking means as specified in the maintenance manual. It cannot be used with a castellated nut and cotter pin. The grip length of the bolt must be carefully matched to the total thickness of the materials being joined. It must be torqued to the value specified in the applicable aircraft maintenance manual (e.g., per AC 43.13-1B).

Documentation

The definitive technical requirements for this component are detailed in Army-Navy specification AN7 and its modern successors. These proprietary documents must be sourced directly from the relevant standards organizations for complete engineering specifications.