Aircraft Fasteners Glossary: Aviation Hardware Standards

Aircraft fasteners are high-integrity joining hardware manufactured under strict aerospace specifications to secure structural assemblies, control surfaces, engine accessories, and interior panels. Unlike commercial hardware, aviation fasteners are engineered to withstand cyclic vibration, high shear and tensile loads, thermal cycling, and corrosive environments without deformation or loss of clamping preload. Fastener identification requires cross-referencing military standards, national aerospace standards, or manufacturer-specific engineering standards against the applicable Aircraft Maintenance Manual or Illustrated Parts Catalog. When sourcing hardware through American Aviation Parts, technicians must ensure that part numbers, material alloy codes, grip lengths, and cadmium or passivation finishes match certified technical data exactly.

Aviation Fastener Terminology

AN Bolts

Air Force-Navy (AN) standard bolts are general-purpose structural threaded fasteners specified by standard AN3 through AN20 diameter designations (in sixteenths of an inch). Manufactured primarily from cadmium-plated SAE 4037 or 8740 alloy steel, corrosion-resistant stainless steel, or aluminum alloy, AN bolts feature close-tolerance unthreaded grip lengths designed to carry pure shear loads across joined Airframe Parts. Bolt heads are marked with raised crosses or dashes to denote alloy composition and magnetic particle testing.

Blind Rivets

Blind fasteners, such as CherryMAX or Huck rivets, are mechanical fasteners designed for structural assembly where access to the bucking tail is limited to only one side of the structure. A pulling mandrel expands the hollow rivet shank against the blind skin, shears at a predetermined tensile limit, and locks the driving collar into place. Blind rivets must strictly adhere to the manufacturer hole diameter and grip range limits outlined in structural repair manuals.

Camloc Fasteners

Camloc is a quick-release quarter-turn fastener mechanism comprising a stud assembly, grommet, retaining ring, and receptacle. Commonly used on engine cowlings, avionics bay doors, and inspection access plates, Camloc fasteners provide high-frequency access while maintaining flush aerodynamics. Installation frequently requires panel surface preparation and chemical bonding compounds found under Adhesives to seal receptacles against vibration fatigue.

Castle Nuts

A castle nut (such as standard AN310) is a slotted, cylindrical nut engineered to receive a cotter pin or safety lockwire through a drilled hole in an AN or NAS bolt shank. The slotted design provides positive mechanical locking in primary flight control linkages, rod ends, and landing gear attachments where rotational friction could otherwise loosen non-positive locking hardware.

Cotter Pins

Standard AN380 and MS24665 cotter pins are split-shank steel or corrosion-resistant safety pins inserted through castle nuts and drilled bolt shanks. Once inserted, the prongs are bent over the end of the bolt and down across the nut flats according to standard maintenance practices to physically prevent the nut from backing off under dynamic loads.

Dzus Fasteners

A Dzus fastener is a proprietary quarter-turn quick-acting fastener featuring a spiral cam slot on the stud body that engages a stationary spring-wire receptacle mounted to the sub-structure. They are widely applied on removable fairings and non-structural fairing panels where rapid maintenance turnarounds are standard for an active AMT/A&P.

Hi-Lok Fasteners

Hi-Lok fasteners are two-piece structural shear pins featuring a threaded pin and a collar with an integral torque-off hex nut. During installation with specialized pneumatic or manual tooling, the driving hex shears off at a calibrated torque level, guaranteeing consistent preload and eliminating the need for independent torque wrench verification in high-stress wing spars and pressure bulkheads.

Lockwire

Also termed safety wire, lockwire is annealed stainless steel or brass wire (commonly 0.020, 0.032, or 0.041-inch diameter) routed through drilled fasteners in reverse-tension safety patterns. Applied via safety wire pliers, it creates opposing mechanical tension that physically prevents fasteners, turnbuckles, and oil filters from loosening in high-vibration operational zones.

NAS Bolts

National Aerospace Standard (NAS) bolts, such as the NAS6200 and NAS6600 series, are ultra-high-strength close-tolerance fasteners designed for severe tensile, shear, and fatigue installations exceeding AN bolt ratings. Featuring 160,000 to 180,000 psi ultimate tensile strength and precise shank tolerances, NAS hardware is critical for landing gear trunnions, engine mount brackets, and wing-attach fittings. Sourcing genuine hardware through American Aviation Parts ensures adherence to original engineering drawing revisions.

Self-Locking Nuts

Self-locking nuts, conforming to AN364, AN365, MS21042, and MS21044 specifications, secure threaded connections without cotter pins. They utilize either a non-metallic fiber/nylon insert or an all-metal deformed thread pitch that produces continuous prevailing torque. Fiber-insert nuts are restricted to low-temperature installations (below 250°F), while all-metal locknuts are required in high-heat engine and exhaust zones.

Solid Shank Rivets

Solid rivets (including 2117-T4 'AD' and 2024-T4 'D' alloys) remain the primary permanent mechanical fasteners in stressed-skin sheet metal aircraft construction. Driven using pneumatic rivet guns and bucking bars, the expanded shank completely fills the reamed or drilled hole, creating an airtight, high-shear joint. Pre-riveting surface deburring often requires fine Abrasives to eliminate micro-cracks before setting.

Procurement and Verification Best Practices

Never substitute standard commercial grade-5 or grade-8 automotive hardware into an aviation application. Aviation fasteners feature specific thread roll profiles, metallurgical purity, grip-to-thread ratios, and quality certifications governed by FAA regulations. For specialized mounting projects, technicians can browse clean-room items from 3M Products or review certified hardware across All Products to ensure full conformity to manufacturer service documents.