AN3-16A – 10-32 x 1-3/4" Hex Head Bolt, Alloy Steel, Cadmium Plated
Available now on the Airparts.aero Marketplace.
Overview
The AN3-16A is a high-strength, general-purpose aerospace fastener manufactured to the foundational Air Force-Navy (AN) standard. This hex head bolt is engineered from heat-treated alloy steel for use in countless structural and systems applications requiring robust clamping force and reliability. With a 3/16-inch diameter and a 1-3/4-inch nominal length, this bolt is a staple for assembling a wide range of aircraft components, particularly where a long grip is necessary.
Conforming to the "A" designation as specified by the "Undrilled Shank" description, this bolt is designed for use with self-locking nuts or other approved locking devices. Protected by a durable cadmium plating for superior corrosion resistance, the AN3-16A is one of the most common fasteners in aviation. Its adherence to the AN specification ensures complete traceability, uniform quality, and the mechanical performance required for flight-critical installations.
Key Features
High-Tensile Alloy Steel: Fabricated from premium alloy steel (typically 4140 or 8740) and heat-treated to a minimum tensile strength of 125,000 PSI for maximum load-carrying capability.
Cadmium Plating: Coated with a sacrificial cadmium layer per QQ-P-416, providing excellent protection against environmental corrosion and ensuring consistent torque-tension relationships.
Rolled Threads: Features #10-32 UNF-3A threads that are cold-rolled, a superior manufacturing process that increases fatigue resistance exponentially compared to cut threads.
Undrilled Shank ("A" Type): The solid, un-drilled shank is designed for use with a variety of self-locking nuts, providing secure fastening in a wide range of tension and shear applications.
Long Grip Design: A 1-3/8-inch grip length makes this bolt ideal for securing thick material stack-ups, ensuring shear loads are borne by the full-diameter shank.
AN Standard Compliance: Guarantees every aspect of the bolt—from material chemistry to dimensional tolerances—meets the rigorous standards required for airworthy components.
Technical Specifications
Part Number: AN3-16A (conforming to the AN3-16 callout with an undrilled shank)
Component Type: Hex Head Machine Bolt
Governing Specification: AN3 / NASM3
Material: Alloy Steel (e.g., 4140, 8740), heat-treated
Minimum Tensile Strength: 125,000 PSI
Finish: Cadmium Plate per QQ-P-416, Type II, Class 2
Diameter: 3/16 inch (0.1875 inches)
Nominal Length (under head to end): 1-3/4 inches (1.750 inches)
Grip Length (Unthreaded Shank): 1-3/8 inches (1.375 inches)
Thread Specification: #10-32 UNF-3A
Aircraft Compatibility
The AN3-16A is a universal standard hardware item used across the entire spectrum of aviation, from light piston aircraft to the largest transport category jets. It is specified in countless locations on aircraft manufactured by:
Textron Aviation (Cessna, Beechcraft, Hawker)
Boeing
Airbus
Bombardier
Embraer
Piper, Cirrus, Diamond, and all other major OEMs.
Note: Verification of applicability is the responsibility of the installer. The grip length must be correctly matched to the total thickness of the material being joined. Always consult the current version of the aircraft's Illustrated Parts Catalog (IPC) or maintenance manual to confirm part number eligibility.
Applications
Assembly of primary and secondary airframe structures with thick cross-sections.
Engine mount attachments on some light aircraft.
Landing gear component attachment and assembly.
Installation of fairings and inspection panels requiring long fasteners.
Securing of interior components, systems hardware, and brackets.
Why Choose AN3-16A?
The use of certified aerospace hardware is non-negotiable for flight safety. An AN3-16A bolt guarantees the precise material properties, heat treatment, and manufacturing processes (like rolled threads) that are essential for resisting the unique stresses of flight, including vibration and cyclic loading. The substitution of a commercial-grade bolt, which lacks these controlled attributes, would introduce a direct and catastrophic risk of joint failure. This certified fastener is the only choice for an airworthy repair.
The engineering significance of the AN3-16A's long grip length is paramount in shear joint design. For a joint to develop its full bearing and shear strength, the load must be transferred through the full, unthreaded diameter of the bolt shank, not the weaker, stress-concentrating threads. The 1.375-inch grip of this bolt is specified for applications where the total thickness of the clamped material stack-up is approximately that dimension. This ensures that the shear planes are located entirely within the smooth shank. This prevents the threads from acting like a file and elongating the holes in the structure under load, a failure mode known as bearing failure. It also ensures the bolt itself is loaded in pure shear across its nominal 0.1875-inch diameter, allowing it to perform to its maximum certified strength and fatigue life.
Note: This is a flight-critical hardware component. Installation must be performed by a certified mechanic. A calibrated torque wrench must be used to apply the correct torque value specified in the maintenance manual to achieve proper clamp load (preload). This bolt must be paired with a corresponding certified aerospace-grade self-locking nut (e.g., MS21044N3 or MS21045N3) to ensure the joint remains secure.
Documentation
The specifications for this fastener are maintained under the National Aerospace Standards (NASM), which have superseded many of the original AN drawings. Publicly accessible summaries of these standards can often be found through standards organizations and authorized hardware suppliers.