The MS20002-4 Washer is a military-standard countersunk aerospace washer designed for flush fastener installations in aircraft structural, aerodynamic, and interior assemblies. It is used with countersunk screws or bolts to ensure a smooth surface profile while distributing clamping loads and protecting the underlying material.

This washer is commonly used in aviation applications where aerodynamic efficiency or clean interior finishing is required, preventing fasteners from protruding above the surface. It is supplied in a 100-piece pack for maintenance, repair, and production operations.

Its primary features include:
Manufactured to MS20002 aerospace military standards
Countersunk design for flush-mounted fastener applications
Used with countersunk screws and bolts
Helps distribute load and reduce surface stress
Suitable for aircraft structural and aerodynamic surfaces
Durable metal construction for aviation environments
Packaged in a 100-piece maintenance set
Compatible with aircraft assembly and repair procedures

Washers like the MS20002-4 are widely used in aerospace systems because they help maintain smooth surface geometry, improve fastening reliability, and reduce localized stress concentrations in aircraft structures.