MS21044N10 - Self-Locking Hexagon Nut

MS21044N10 – Self-Locking Hexagon Nut

Available now on the Airparts.aero Marketplace.

Overview

The MS21044N10 is a military-standard, prevailing torque, self-locking hexagon nut, a heavy-duty and essential piece of hardware for aerospace and high-performance vehicle applications. Commonly referred to as a "nyloc" nut, it is engineered to resist loosening under the severe vibration conditions of flight. This nut features a captive nylon locking collar that provides a consistent, reliable locking action. Manufactured from high-strength steel and plated for corrosion resistance, the MS21044N10 is the industry standard for securing large 5/8-inch bolts and screws in a multitude of non-structural and secondary structural applications.

Key Features

• Nylon Insert Locking Mechanism: The defining feature is an integrated nylon (polyamide) collar at the top of the nut. As a bolt is threaded through, the nylon insert is elastically deformed, creating a powerful, uniform frictional grip on the threads that provides prevailing torque and prevents loosening.
• Vibration Resistance: The prevailing torque created by the nylon insert makes this nut exceptionally resistant to loosening from high-frequency airframe and engine vibration, eliminating the need for secondary locking devices like cotter pins or lock washers in many applications.
• High-Strength Steel Construction: Fabricated from a high-quality carbon steel alloy, providing the tensile strength required to properly preload large-diameter structural bolts.
• Corrosion-Resistant Plating: Plated with a durable cadmium finish per specification QQ-P-416. This protective coating provides excellent resistance to environmental corrosion.
• MS Certified Standard: As a certified Military Standard part, it guarantees the material, dimensions, thread quality, and locking torque performance meet the stringent requirements for use in certified aircraft. It is the superseding part for the legacy AN365-1018 nut.

Technical Specifications

• Standard: MS21044 (Nut, Self-Locking, Hexagon, Regular Height, 250°F)
• Full Part Number: MS21044N10
• Legacy Part Number: AN365-1018
• Material (N): Carbon Steel
• Finish: Cadmium Plated
• Locking Element: Nylon (Polyamide) Insert
• Thread Specification: 5/8-18 UNF-3B
  • Nominal Diameter: 5/8 inch (0.625 inches)
  • Threads Per Inch: 18 (Fine Thread)
• Wrench Size: 15/16 inch
• Maximum Operating Temperature: 250°F (121°C)

Aircraft Compatibility

The MS21044N10 is a universal hardware component used on a wide variety of aircraft where a heavy-duty, 5/8-inch self-locking nut is required for applications that do not exceed its temperature limitations.

• Common Applications:
  • Airframe Assembly: Securing major structural components, brackets, and fittings in cooler areas of the airframe.
  • Landing Gear Systems: Used on various non-heat-critical landing gear components.
  • Wing & Strut Attachments: Securing major attach points where temperature is not a factor.

Applications

The MS21044N10 is the go-to fastener for creating secure, large-diameter bolted joints:

• General-Purpose Heavy-Duty Fastening: The workhorse locknut for the majority of non-structural and secondary structural joints requiring a 5/8" fastener.
• Serviceable Joints: Allows for fasteners to be removed and reinstalled for maintenance while still providing a reliable locking action upon re-torquing (subject to inspection).

Why Choose MS21044N10?

A fastener that has loosened due to vibration can lead to component failure. The MS21044N10 provides a simple, lightweight, and highly effective solution to this problem for large hardware. Using a genuine MS-standard nut ensures that the part has the certified material strength, thread quality, and, most importantly, the correct prevailing torque characteristics to function as a reliable locking device. Substituting with non-certified commercial-grade locknuts is strictly prohibited in aviation as they lack the rigorous quality control and traceability required for flight-critical applications.

Order Your MS21044N10 Nuts Now

Stock your shop with the industry-standard flight-certified locknut for heavy-duty applications. Visit Airparts.aero to order your MS21044N10 self-locking nuts today.

The MS21044N10 self-locking nut functions by creating "prevailing torque." This is a measured resistance to rotation that exists even when the nut is not seated against a surface. The locking action is created as the male threads of the bolt engage the smaller-diameter nylon ring, which elastically deforms and creates a 360-degree frictional grip. This constant pressure on the threads prevents the nut from moving relative to the bolt, even when subjected to intense vibration. The 250°F temperature limit is critical; above this temperature, the nylon insert will soften, lose its elasticity, and its locking ability will be significantly reduced or eliminated. For applications exceeding this temperature, an all-metal high-temperature locknut must be used.

Note: This is a flight-critical component. It must be tightened using a calibrated torque wrench to the value specified in the applicable maintenance manual. While reusable, the nut must be discarded if it can be run down to the seating surface by hand, as this indicates the nylon locking element has lost its effectiveness.

Product Overview

A nut having a flat bottom and 6 sides. An integral feature is incorporated for locking on the threads of a mating member. Excludes nut (1), self-locking, cap.

Specifications

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