MS9489-06 - Textron Aviation OEM Hex Head Machine Bolt

MS9489-06 – Textron Aviation OEM 1/4-28 x 1/2" High-Strength (160ksi) Drilled Head Bolt

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Overview

The MS9489-06 is a high-strength, military-specification hex head bolt, supplied with the full certification and traceability of Textron Aviation as an Original Equipment Manufacturer (OEM) component. This is not a standard AN bolt; it is an engineered fastener with a significantly higher strength rating, designed for the most demanding, flight-critical structural applications. Its key characteristic is a minimum tensile strength of 160,000 PSI, a substantial increase over the 125,000 PSI of a standard AN bolt.

This fastener is manufactured from a superior grade of alloy steel and features a drilled head for positive locking with safety wire. With a 1/4-inch diameter and a 1/2-inch nominal length, this bolt is specified for high-stress joints where a combination of high clamp load, tensile strength, and vibration resistance is required. As a genuine Textron Aviation part, it is the factory-certified hardware for maintaining the structural integrity of their high-performance aircraft.

Key Features

• Textron Aviation OEM Certified: Guarantees the part is the factory-approved, fully traceable component for the Textron Aviation family of aircraft.

• 160,000 PSI High-Tensile Strength: Heat-treated to a minimum tensile strength of 160 ksi, providing a significantly higher load-carrying capability than standard AN series bolts.

• High-Grade Alloy Steel: Forged from a premium alloy steel (such as 4140 or 4340) selected for its superior hardenability and toughness.

• Drilled Head for Lockwiring: The hexagonal head is cross-drilled to facilitate the installation of safety wire, creating a positive, anti-rotation locking mechanism.

• Cadmium Plated for Corrosion Resistance: Coated with a sacrificial cadmium layer per QQ-P-416 for exceptional protection against environmental corrosion.

• Rolled Threads: Features 1/4-28 UNF-3A threads that are cold-rolled, a superior manufacturing process that increases fatigue resistance exponentially.

Technical Specifications

• Part Number: MS9489-06

• Component Type: High-Strength Drilled Head Hex Bolt

• OEM Authority: Textron Aviation

• Governing Specification: MS9489

• Material: High-Grade Alloy Steel (e.g., 4140, 4340), heat-treated to 160-180 ksi

• Minimum Tensile Strength: 160,000 PSI

• Finish: Cadmium Plate per QQ-P-416, Type II

• Diameter: 1/4 inch

• Nominal Length (under head to end): 1/2 inch (0.500 inches)

• Grip Length (Unthreaded Shank): 5/32 inch (0.156 inches)

• Thread Specification: 1/4-28 UNF-3A

Aircraft Compatibility

As a Textron Aviation OEM part, this high-strength fastener is specified in critical structural locations on their higher-performance aircraft.

• Primary Textron Aviation Platforms:

  • Cessna Citation Series Business Jets

  • Beechcraft King Air Series

  • Hawker Business Jets

• General Aerospace Usage: Used across the industry in primary structural joints where the 125ksi strength of a standard AN bolt is insufficient.

Note: Verification of applicability is the responsibility of the installer. Always consult the current version of the aircraft's Structural Repair Manual (SRM) or Illustrated Parts Catalog (IPC) to confirm part number eligibility.

Applications

• Primary structural joints in wings, fuselage, and empennage.

• Landing gear attachment fittings and trunnions.

• Flight control surface hinge points.

• Engine mount attachments and pylon structures.

• Any high-stress joint where the engineering drawing explicitly calls for a 160ksi fastener.

Why Choose this MS9489-06?

Hardware substitution is one of the most dangerous errors in aircraft maintenance. The MS9489-06 is visually similar to a standard AN4 bolt but possesses a 28% higher tensile strength. Substituting a lower-strength AN bolt where an MS9489 is specified will result in a joint that is incapable of carrying its designed structural load, leading to certain and catastrophic failure. Using the genuine Textron Aviation OEM MS9489-06 is the only way to guarantee you are installing a fastener with the correct material, heat treatment, and quality control necessary to achieve this critical strength rating.

The ability of the MS9489-06 bolt to achieve its 160,000 PSI tensile strength is a direct result of its advanced material science. It is typically fabricated from a nickel-chrome-molybdenum alloy steel like 4340. The addition of nickel increases the steel's toughness and impact resistance, while chromium and molybdenum significantly increase its hardenability. Hardenability is the property that allows the steel to form a hard martensitic microstructure to a greater depth during the quenching process. This deep hardness is critical; it ensures that the bolt is not just hard on the surface but possesses its full strength through the entire cross-section. Following the quench, a precise tempering process is used to reduce brittleness and achieve the final desired balance of ultimate tensile strength and fracture toughness, producing a fastener capable of withstanding the immense loads of primary aircraft structures.

Note: This is a flight-critical structural fastener. It must NOT be substituted with a standard AN bolt. Installation must be performed by a certified mechanic in strict accordance with the Structural Repair Manual (SRM). A calibrated torque wrench must be used to apply the correct torque value to achieve the higher preload associated with its strength. Safety wire must be installed per standard practices.

Documentation

The military standard governing this part is publicly available through the Department of Defense ASSIST database. OEM-specific application and installation data is contained within the Textron Aviation maintenance and structural repair manuals.

• ASSIST Document Summary Page for MS9489: http://quicksearch.dla.mil/qsDocDetails.aspx?ident_number=38501