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AN5-13A – Textron Aviation OEM Undrilled Hex Head Bolt
Available now on the Airparts.aero Marketplace.
The Textron Aviation AN5-13A is a high-performance, structural aerospace fastener manufactured to rigorous Army-Navy (AN) standards and certified for use across the Textron family of aircraft, including Cessna, Beechcraft, and Hawker. This 5/16-24 UNF-3A hex head bolt is engineered for primary and secondary structural applications where high shear strength and reliability are non-negotiable. The "A" suffix specifically identifies this bolt as "undrilled," meaning it lacks the safety wire holes in the head and the cotter pin hole in the shank. This design is intended for use with prevailing torque self-locking nuts (such as MS21044 or NAS1352), facilitating a lighter, more streamlined assembly in non-rotating joints.
As an OEM component sourced through Textron Aviation, the AN5-13A guarantees exact metallurgical properties and dimensional tolerances that meet or exceed MIL-B-6812 specifications. A critical aspect of this bolt is its precise 0.938-inch grip length. In aviation maintenance, ensuring the "grip" (the unthreaded portion of the shank) extends through the entire thickness of the joined materials is vital; this prevents the threads from bearing against the hole walls, which would cause significant stress concentration and potential joint failure. From securing engine mounts to primary airframe brackets, the Textron AN5-13A provides the certified strength required to maintain the structural airworthiness of high-utilization aircraft.
Key Features
Aerospace-Grade Alloy Steel: Fabricated from high-carbon heat-treated steel (AISI 4037 or 8740) to ensure a minimum tensile strength of 125,000 psi.
Cadmium II Plating: Finished with yellow dichromate cadmium plating (QQ-P-416) for superior galvanic corrosion protection and a stabilized friction coefficient for accurate torque application.
Cold-Forged Construction: The hex head is cold-headed to create a continuous internal grain flow, significantly increasing the bolt's resistance to fatigue and head-to-shank separation.
Optimized Grip Length: Features a 15/16" (0.938 in) unthreaded shank designed to carry shear loads across the full diameter of the bolt.
Fine Thread Precision: The 5/16-24 UNF-3A threads provide superior vibration resistance and higher clamping forces compared to coarse thread alternatives.
Technical Specifications
Part Number: AN5-13A
OEM Manufacturer: Textron Aviation (Cessna / Beechcraft)
Thread Size: 5/16-24 UNF-3A (Fine Thread)
Bolt Type: Hex Head, Structural, Undrilled5
Material: 4037 or 8740 Chromoly Alloy Steel
Finish: Cadmium Plate, Type II (Yellow), Class 2
Overall Length: 1.469 inches
Grip Length: 0.938 inches
Tensile Strength: 125,000 psi (Minimum)
Shear Strength: 75,000 psi (Minimum)
Governing Specifications: AN5 through AN20 series / MIL-B-6812
Certification: FAA-PMA / OEM Original Equipment
Aircraft Compatibility
Cessna 172, 182, 206, and 210 Series
Beechcraft Bonanza (33/35/36) and Baron (55/58)
Beechcraft King Air 90, 200, and 300 Series
Hawker 400XP / 800XP
Note: Always verify the specific application and part number in the aircraft's Illustrated Parts Catalog (IPC) to ensure correct serial number effectivity.
Applications
Structural Brackets: Securing primary airframe components where vibration is high and shear loads are present.
Control System Linkage: Used in non-pivoting junctions where self-locking nuts are the preferred secondary retention method.
Engine & Accessory Mounts: Providing high-strength clamping for engine-to-airframe interfaces.
Why Choose AN5-13A?
When maintaining Textron aircraft, utilizing OEM-verified hardware like the AN5-13A is essential for safety and regulatory compliance. Commercial "Grade 8" fasteners found in hardware stores do not possess the documented "heat-treat" traceability or the specific "grip-to-thread" ratio required for aviation. An incorrect grip length can lead to "thread-bearing" in a shear joint, which drastically reduces the fatigue life of the assembly. By choosing the Textron OEM AN5-13A, you ensure the fastener aligns perfectly with the engineering design intent, maintaining the aircraft's safety margins and resale value.
The AN5-13A is designed to function within a clamped joint system where the bolt acts as a high-tension spring. The engineering principle relies on Preload, which is the tension created in the bolt when it is torqued. This preload creates a Clamping Force that generates friction between the joined members, allowing the joint to resist shear loads through friction rather than just the physical bearing of the bolt against the hole.
Because this is an undrilled bolt, the cross-sectional area is not compromised by a cotter pin hole, eliminating a major stress riser and improving the bolt's fatigue limit. The material choice of 4037 or 8740 alloy steel provides high hardenability and toughness. The Cadmium plating serves two roles: it prevents galvanic corrosion between dissimilar metals (like a steel bolt in an aluminum airframe) and provides a consistent nut factor ($K$), ensuring that the torque applied by the mechanic translates accurately into the desired clamping force without being lost to friction.
Note: The AN5-13A is a structural fastener. It is an "undrilled" bolt and must NOT be used in applications where a cotter pin or safety wire is required by the maintenance manual. Use only with approved prevailing torque locknuts. Installation must be performed by a certified A&P mechanic using calibrated torque tools in accordance with the Aircraft Maintenance Manual (AMM) and FAA Advisory Circular AC 43.13-1B.
