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81783-1018 – Textron Aviation OEM Wing Attachment Nut
Available now on the Airparts.aero Marketplace.
Overview
The Textron Aviation 81783-1018 is a flight-critical, OEM Aft Wing Attachment Nut. This is a primary structural fastener, specified for use in the main wing bolt installation kits (e.g., 101-4026-3 S, 101-4026-7) on Beechcraft King Air 200 and 300 series aircraft. Its sole and essential function is to secure the aft main wing bolt (e.g., P/N 81786-10-20), which is one of the primary fasteners holding the wing to the fuselage.
This is a high-performance, self-locking, flanged nut engineered for a "no-fail" mission. It is manufactured from Inconel 718, a nickel-chromium superalloy, and finished with a cadmium plating. This material is specified for its immense tensile strength, exceptional fatigue life, and superior resistance to corrosion and high temperatures. The double-hexagon (12-point) head allows for high-torque application and secure engagement, while the integrated flange distributes the clamp load over a wider area, preventing damage to the airframe structure.
Key Features
Genuine Textron Aviation OEM Part: The only factory-certified nut for this primary structural application, guaranteeing material, strength, and performance.
Flight-Critical Structural Fastener: A primary component in the wing-to-fuselage attachment, engineered to carry immense flight loads.
Inconel 718 Superalloy Construction: Manufactured from one of the strongest and most resilient aerospace superalloys, providing exceptional strength and fatigue resistance at all temperatures.
Double-Hexagon (12-Point) Head: Allows for reliable, high-torque application without the risk of stripping that a 6-point nut would have at this torque level.
Self-Locking & Flanged Design: Features an integrated all-metal locking mechanism that is immune to high temperatures and a flange that provides a wide, secure load-bearing surface.
Cadmium Plated: Provides a sacrificial layer of corrosion protection.
Technical Specifications
Part Number: 81783-1018
Component Type: Nut, Double Hexagon, Flanged, Self-Locking
OEM Manufacturer: Textron Aviation (Hawker Beechcraft)
Application: Aft Wing Attachment Bolt
Thread Size: 5/8" (0.625 inch)
Material: Inconel 718 Nickel-Chromium Superalloy
Finish: Cadmium Plated
Aircraft Compatibility
Beechcraft (Textron Aviation): King Air 200, B200, 300, B300 (350)
Note: This is a primary structural fastener. The aircraft's specific Illustrated Parts Catalog (IPC) and Structural Repair Manual (SRM) are the final and absolute authorities for determining part applicability and installation procedure. This part is typically replaced as part of a complete wing bolt kit.
Applications
Primary Wing Attachment: The sole application for this nut is to secure the aft main wing attachment bolt, a critical structural joint.
Why Choose 81783-1018?
There is no substitute for a genuine, certified wing attachment nut. The 81783-1018 is an engineered component designed to handle the combined, multi-axial loads that the wing experiences in flight—from lift and turbulence to G-loads and landing impacts. Using a non-certified, "will-fit," or commercial-grade nut would be a catastrophic risk. The genuine Textron OEM part is the only component guaranteed to be made from the specified Inconel 718 superalloy, with the correct heat treatment and manufacturing processes required to ensure the structural integrity of the aircraft.
The engineering significance of the 81783-1018 nut is its Inconel 718 superalloy construction. This material is a precipitation-hardenable nickel-chromium alloy. Unlike standard steel, its strength is derived from microscopic intermetallic precipitates (
phases) that are "grown" within the metal's crystal structure during a precise heat-treatment process. These precipitates act as powerful obstacles to deformation, giving Inconel 718 an incredibly high tensile strength (often exceeding 185,000 PSI) and, most critically, exceptional fatigue strength. The wing joint experiences millions of microscopic load cycles during every flight from vibration and flex. This nut is specifically engineered to resist the initiation and propagation of fatigue cracks for the entire life of the airframe, a property that standard steel fasteners cannot guarantee.
Note: The 81783-1018 is a flight-critical structural fastener. Installation is a major airframe maintenance task that must be performed by a certified A&P/IA mechanic in strict accordance with the Textron Aviation King Air maintenance manual. It must be paired with the correct bolt (81786-10-20) and washers, and tightened to the specific, high torque value listed in the manual. These are often "replace on removal" items.
Documentation
No public-facing OEM specification sheet was located for this proprietary part number. All authoritative technical data, installation procedures, torque specifications, and life limits are contained within the official Textron Aviation King Air Series Maintenance Manual and Illustrated Parts Catalog (IPC).
