MS9245-25 - Aerospace Cotter Pin

MS9245-25 – Aerospace Cotter Pin

Available now on the Airparts.aero Marketplace.

Overview

The MS9245-25 is a military-standard cotter pin engineered for high-performance aerospace applications where superior corrosion resistance is a primary requirement. Manufactured in strict accordance with the MS9245 specification, this pin is fabricated from high-quality, corrosion-resistant steel (CRES), typically Type 321 stainless steel. It is designed to provide a simple, yet highly reliable, positive locking mechanism for castellated nuts, bolts, and other fasteners, ensuring they do not loosen under the severe vibration and harsh environmental conditions encountered in flight.

Key Features

• Corrosion-Resistant Steel (CRES): Fabricated from high-grade stainless steel (typically T321). This material provides excellent inherent protection against rust and corrosion without the need for plating, making it ideal for external applications or in areas exposed to moisture and corrosive fluids.
• Positive Mechanical Locking: Serves as a definitive locking device for castellated nuts. Once installed, it creates a physical barrier that prevents the nut from rotating loose, a fundamental requirement for safety-of-flight hardware.
• Extended Prong, Chisel Point Design: Features one tine that is slightly longer than the other to aid in separation for installation, and chisel points for easy insertion into drilled holes.
• MS Certified Standard: As a certified Military Standard part, it guarantees the material composition, dimensional accuracy, and quality control required for use in certified aircraft, ensuring full traceability and airworthiness.

Technical Specifications

• Standard: MS9245 (Pin, Cotter, Split, Corrosion-Resistant Steel)
• Full Part Number: MS9245-25
• Material: Corrosion-Resistant Steel (CRES), typically T321 Stainless Steel
• Finish: Passivated
• Nominal Diameter: 1/16 inch (0.063 inches)
• Length: 1/2 inch (0.500 inches), measured from under the head loop.
• Point Type: Extended Prong, Chisel/Square Cut

Aircraft Compatibility

The MS9245-25 is a universal piece of hardware used across all categories of aircraft, from general aviation to commercial transport and military platforms. It is specified in any application where a 1/16" x 1/2" corrosion-resistant cotter pin is required by the manufacturer's parts catalog or maintenance manual.

• Common Applications:
  • Exterior Airframe: Securing fasteners on landing gear, fairings, and inspection panels exposed to the elements.
  • Engine Compartment: Used on firewall-forward components where heat and fluid exposure make corrosion a concern.
  • Flight Controls: Locking nuts on control linkages and bellcranks.
  • Marine/Amphibious Aircraft: An essential hardware choice for aircraft operating in saltwater environments.

Applications

The MS9245-25 is the specified solution for ensuring the long-term integrity of bolted joints:

• Securing Castellated Nuts: Installed through a drilled bolt or stud to secure a castellated nut (e.g., AN310, AN320), preventing rotation.
• Corrosion Prevention: The ideal choice over standard cadmium-plated steel (MS24665) pins in areas where plating may be compromised or where galvanic compatibility with other stainless steel components is required.
• Safety Locking: Provides a simple, visually verifiable confirmation that a critical fastener is properly secured.

Why Choose MS9245-25?

The failure of a cotter pin can lead to the loosening of a critical fastener, potentially resulting in catastrophic failure. Using a genuine MS9245-25 cotter pin guarantees you are installing a part with a certified material composition designed to resist corrosion and failure. While a cadmium-plated pin provides good protection, a stainless steel pin offers superior, inherent corrosion resistance for the entire part, not just a surface coating. For applications demanding the highest level of durability and corrosion protection, the MS9245 series is the professional and airworthy choice.

Order Your MS9245-25 Cotter Pins Now

Stock your workshop with flight-critical, certified hardware for the most demanding applications. Visit Airparts.aero to order your MS9245-25 stainless steel cotter pins today.

The MS9245 standard specifies cotter pins made from corrosion-resistant steel, distinguishing them from the cadmium-plated carbon steel MS24665 series. Type 321 stainless steel is often used due to its excellent resistance to intergranular corrosion and its good strength properties. The pin functions by being inserted through a hole in a bolt shank, nestled within the slots of a castellated nut. The tines are then bent apart using standard aviation practices (one tine over the top of the bolt, one bent down against the nut flat) to create a mechanical lock that physically blocks the nut from turning. This simple, effective, and inspectable system is a foundational element of aerospace safety engineering.

Note: Cotter pins are strictly single-use items. A pin that has been installed and bent must never be straightened and reused, as this can cause unseen stress fractures. Always use a new pin for every installation and verify the correct size from the applicable maintenance manual.