S1131-1 - Textron Aviation OEM Nylon Insert

S1131-1 – Textron Aviation OEM Nylon Insert for MS21047-06 Anchor Nuts

Available now on the Airparts.aero Marketplace.

Overview

The S1131-1 is a genuine Textron Aviation Original Equipment Manufacturer (OEM) replaceable nylon locking insert. This is not a complete nut, but a critical service component for specific types of self-locking anchor nuts. Its primary application is to restore the self-locking capability of the MS21047-06 series of lightweight, floating anchor nuts. This component allows the prevailing torque feature of the nut to be renewed without the need to perform a structural repair by drilling out and replacing the entire riveted anchor nut assembly.

Identifiable by its red color, the S1131-1 is designed for anchor nuts that accept a #6-32 screw. The nylon material provides a consistent, reliable friction grip on the screw's threads. As a genuine Textron OEM part, this insert is manufactured from the correct, certified polymer and to the precise dimensions required to restore the original locking performance of the host nut assembly.

Key Features

• Genuine Textron Aviation OEM Part: Guarantees the part is fabricated to the exact Textron engineering drawing for material, dimensions, and locking performance.

• Replaceable Locking Element: A cost-effective service part that allows for the renewal of an anchor nut's locking feature, dramatically reducing maintenance time and cost.

• Restores Prevailing Torque: A new insert restores the nut's ability to resist loosening from vibration, ensuring the joint remains secure.

• For MS21047-06 Anchor Nuts: Specifically designed as the replacement insert for the common MS21047-06 floating anchor nut, which is used for #6-32 screws.

• Color Coded for Identification: The red nylon material provides positive identification for the specific part number and size.

• 250°F Temperature Rating: The nylon polymer is suitable for general airframe applications where temperatures will not exceed 250°F (121°C).

Technical Specifications

• Part Number: S1131-1

• Component Type: Replaceable Self-Locking Nut Insert

• OEM Authority: Textron Aviation

• For Use In: MS21047-06 floating anchor nuts and equivalent series.

• For Screw Size: #6-32 UNC/UNF

• Material: Nylon (or equivalent polyamide), Red.

• Maximum Operating Temperature: 250°F (121°C)

• Governing Specification: Textron Aviation Engineering Drawing S1131.

Aircraft Compatibility

This replaceable insert is used on Textron Aviation aircraft that employ the MS21047-06 series anchor nut.

• Primary Textron Aviation Platforms:

  • Cessna Piston Aircraft

  • Cessna Caravan Series

  • Cessna Citation Business Jets

  • Beechcraft and Hawker models

Note: Verification of applicability is the absolute responsibility of the installer. The aircraft's current Illustrated Parts Catalog (IPC) for its specific serial number is the final authority for confirming part number eligibility.

Applications

• Sole Application: To be installed into the nut element of an MS21047-06 anchor nut (or equivalent) to restore its self-locking, prevailing torque capability. These anchor nuts are commonly used for securing:

  • Inspection panels and access covers

  • Fairings and non-structural components

  • Interior panels and upholstery

Why Choose S1131-1?

The prevailing torque of a self-locking nut is a flight-critical safety feature that prevents fasteners from backing out under vibration. Over time and with multiple uses, this locking ability degrades. The S1131-1 is the only certified replacement insert guaranteed to restore the original, specified locking performance of the host nut assembly. Using a non-certified insert or failing to replace a worn one negates the self-locking feature entirely, creating an unairworthy condition where a panel or component could come loose in flight.

The S1131-1 is a key component in an advanced, serviceability-focused fastening system. The MS21047 anchor nut, for which this insert is designed, is a "floating" nut plate. Its nut element, which contains the S1131-1 nylon insert, is not rigidly fixed to the riveted base but is allowed to move radially within a cage by a specified amount (e.g., .015" to .030"). This "float" is a critical design feature that accommodates the small misalignments that are inevitable in a large assembly of sheet metal panels and structures. It allows the screw to easily engage the nut threads without cross-threading or binding, which would otherwise damage the screw, the nut, or the structure. The replaceable S1131-1 insert is the final piece of this design, allowing the primary wear item—the nylon locking collar—to be quickly and inexpensively replaced without disturbing the riveted, structural part of the nut assembly.

Note: This is a flight-critical component. The 250°F temperature limitation of the nylon material must be strictly observed. Installation of the insert into the nut element must be done carefully to ensure it is fully seated. After installation, the prevailing torque of the renewed nut assembly should be checked with a bolt or screw to ensure it meets the minimum "run-on" torque specified in the aircraft maintenance manual. If a screw can be turned through the insert by hand, it is unserviceable.

Documentation

All technical data, installation procedures, and torque specifications are proprietary to Textron Aviation. This information is contained within the official Maintenance Manual and Standard Practices documents for the applicable aircraft model. No public-facing documentation is available.