?unique=700cc1e)
KP6AFS464 – Timken Fafnir Airframe Ball Bearing
Available now through the AirParts Aero marketplace.
Overview Section
The Timken KP6AFS464 is a high-precision Airframe Control Ball Bearing specifically designed for oscillating and rotating applications within an aircraft's flight control system.1 Manufactured by Timken’s Fafnir division, this bearing is engineered to handle the unique demands of aerospace environments, where low-speed oscillation, high static loads, and exposure to the elements are common.
This bearing is part of the KP series, which features a single-row, deep-groove ball design.2 It is "Double-Shielded" or "Double-Sealed" to retain factory-applied high-temperature grease and exclude contaminants.3 The AFS464 suffix denotes specific aerospace-grade internal clearances and specialized cadmium or zinc-nickel plating on the external surfaces to prevent corrosion in unpressurized areas of the airframe.
Key Features Section
Deep-Groove Geometry: Optimized for radial loads while providing significant thrust (axial) load capability, essential for control linkages.
Corrosion Protection: The outer and inner rings are typically plated with cadmium (or a modern equivalent) to resist oxidation in high-moisture environments.
Factory Lubricated: Pre-packed with MIL-PRF-23827 or equivalent grease, designed to remain stable from -65°F to +250°F.
Integral Seals: Equipped with low-friction contact seals that retain lubricant and protect the internal raceways from dust, de-icing fluids, and moisture.
Compact, Lightweight Design: The thin-section profile allows for integration into tight flight control pulleys, bellcranks, and push-pull rod ends without adding unnecessary weight.
Precision Tolerances: Manufactured to ABEC-3 or higher standards, ensuring smooth control "feel" and eliminating play (slop) in the pilot's input path.
Technical Specifications Section
| Specification | Detail |
| Part Number | KP6AFS464 |
| Manufacturer | Timken (Fafnir) |
| Bore Diameter | 0.3750 in (3/8") |
| Outside Diameter | 0.8750 in (7/8") |
| Width | 0.2812 in (9/32") |
| Bearing Type | Airframe Control Ball Bearing |
| Seal Type | Double Sealed (Contact) |
| Material | High-Carbon Chrome Steel (Plated) |
| Static Load Rating | Approx. 1,000 lbs |
Aircraft Compatibility Section
The KP6AFS464 is a primary component used in the flight control systems of various airframes:
Textron Aviation (Cessna/Beechcraft): Found in rudder pedal linkages, elevator bellcranks, and aileron pulley assemblies on King Air and Citation models.
Piper Aircraft: Utilized in the control columns and stabilizer trim systems of the PA-31 Navajo and PA-42 Cheyenne.
General Aviation: A common replacement bearing for control surface hinges and push-rod ends in a wide range of light twins and turboprops.
Military & Defense: Used in secondary flight control actuators for various transport and utility aircraft.
Technical Applications & Safety
Flight control bearings operate in a "limited rotation" environment, often oscillating only a few degrees back and forth. This can lead to a condition known as Brinelling, where the balls wear microscopic indentations into the raceway.
Safety Warning: Check for "Notchiness." During a 100-hour or Annual inspection, disconnect the control linkage and rotate the bearing by hand. If you feel any "flat spots," "clicks," or resistance (notchiness), the bearing is worn or brinelled and must be replaced. A seized KP6AFS464 can lead to stiff controls or, in extreme cases, a jammed flight control surface. Never attempt to "re-grease" a sealed bearing by puncturing the seal; this allows contaminants in and leads to rapid failure.
Technical Engineering Insight
The engineering value of the KP6AFS464 lies in its Boundary Lubrication performance. Because flight control bearings rarely complete a full 360-degree rotation, they do not develop a "hydrodynamic film" of oil. Timken designs the raceways with a specific surface finish that allows the grease's chemical additives to provide protection even at zero velocity. The AFS464 specification ensures the bearing can handle "static heavy loads"—such as the forces applied to the elevators during high-speed maneuvers—without the balls deforming the raceway.
Installation & Maintenance Addendum
Press-Fit Caution: When installing the bearing into a housing or bellcrank, apply pressure only to the outer ring. Applying pressure to the inner ring during installation will "shock" the balls and damage the raceways before the bearing ever sees flight.
Snap Ring Inspection: Ensure the retaining snap ring is fully seated in the groove. A bearing that "walks" out of its housing can cause the control linkage to bind against the airframe structure.
Cleanliness: Keep the bearing in its protective wax paper until the moment of installation. Even microscopic grit from a hangar floor can penetrate the seals and lead to premature wear.
