0841004-3 – Textron Aviation OEM Main Landing Gear Axle Key Washer
Available now on the Airparts.aero Marketplace.
Overview
The 0841004-3 is a flight-critical, positive locking device, specifically the genuine Textron Aviation (Cessna) Original Equipment Manufacturer (OEM) key washer for the main landing gear axle nuts. This is not a standard flat washer; it is an engineered component designed to mechanically lock the wheel bearing retainer nut in place. Its function is absolutely essential for safety, as it prevents the axle nut from backing off due to rotational forces and vibration, thereby ensuring that the correct wheel bearing preload is maintained at all times.
Manufactured from a high-strength yet ductile steel alloy, the washer features an inner key that engages with a slot on the axle and one or more outer tabs. After the axle nut is torqued to the precise specification to set the bearing preload, a tab is bent up against a flat on the nut, creating a positive, physical lock. As the genuine OEM part, this washer is guaranteed to be fabricated to the exact engineering drawing, ensuring a perfect fit and reliable function.
Key Features
Genuine Textron Aviation OEM Part: Guarantees the part is fabricated to the exact Textron engineering drawing for material, thickness, and dimensional tolerances, ensuring a perfect fit and reliable function.
Positive Mechanical Lock: Provides a physical barrier that prevents the axle nut from rotating, a more secure method than friction-based locking for critical rotating assemblies.
Keyed/Tabbed Design: Features an inner key to prevent washer rotation and outer tabs that are bent to lock the nut, providing a simple, robust, and visually verifiable lock.
High-Strength Formable Steel: Manufactured from a specific steel alloy that is strong enough to resist shear and fatigue, yet ductile enough to be bent into its locking position without fracturing.
Locks Wheel Bearing Retainer Nut: Specifically designed for the main landing gear axle application on a vast range of Cessna aircraft, a critical safety-of-flight function.
Technical Specifications
Part Number: 0841004-3
Component Type: Key Washer / Tab Washer / Lock Washer
OEM Authority: Textron Aviation (Cessna)
Application: Main Landing Gear Wheel Bearing Retainer Nut Lock
Material: Steel, Plated. The exact alloy and finish must be confirmed by Textron Aviation documentation.
Governing Specification: Textron Aviation Engineering Drawing 0841004.
Aircraft Compatibility
This OEM key washer is the specified component for the main landing gear axle on numerous Cessna single-engine aircraft.
Primary Textron Aviation Platforms:
Cessna 172
Cessna 177
Cessna 180, 182, 185
Cessna 206, 207
Cessna 210
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 and absolute authority for confirming part number eligibility.
Applications
Sole Application: To provide a positive, mechanical lock for the main landing gear axle nut on specified Cessna models, thereby securing the wheel and bearing assembly.
Why Choose 0841004-3?
The safe operation of an aircraft's landing gear is non-negotiable. The failure of a wheel bearing assembly due to an improperly secured axle nut can be catastrophic, potentially leading to a wheel departing the aircraft during takeoff or landing. The 0841004-3 key washer is the specified safety device to prevent this. Only the genuine Textron OEM part is guaranteed to have the correct material properties (strength and ductility) and precise dimensions for this critical, high-stress application. The use of a non-certified part would create an unacceptable risk of landing gear failure.
The engineering principle behind the use of a key washer like the 0841004-3 in a wheel bearing application is the necessity of a positive lock to maintain a precise preload setting, rather than a friction lock designed to maintain a high clamp load. The axle nut on a tapered roller bearing is not tightened to a high torque value; instead, it is torqued through a specific procedure (e.g., torque to seat the bearings, then back off and re-torque to a much lower value) to achieve a minute amount of bearing end-play or a light preload. This setting is critical for the longevity of the bearings. A prevailing torque locknut is unsuitable as its friction can interfere with accurately feeling the bearing preload. The key washer allows the nut to be precisely positioned and then physically locked in that position by bending the tab. This ensures the critical bearing preload setting is maintained, preventing bearing overheating (too tight) or wheel wobble and brinelling (too loose).
Note: This is a flight-critical, single-use hardware component. A new key washer must be used every time the axle nut is removed and re-installed. The tabs are not designed to be bent more than once. Installation must be performed by a certified A&P mechanic in strict accordance with the aircraft maintenance manual, which provides the detailed, multi-step procedure for torquing the axle nut to set the correct bearing preload before the lock tab is bent.
Documentation
All technical data, installation procedures, and torque specifications for the 0841004-3 key washer are proprietary to Textron Aviation. This information is contained within the official Maintenance Manual for the applicable Cessna model. No public-facing documentation is available.