EN 4425:2006

Overview

EN 4425:2006 is a European standard developed by CEN that specifies the characteristics and dimensions of tab washers made of corrosion-resistant steel for aerospace flight control rods. These tab washers are critical components designed to immobilize the rod end relative to the rod body while permitting positional adjustments. This ensures reliable control and safety in aircraft flight control systems.

The standard details precise requirements for dimensions, surface roughness, material specifications, marking, and quality management to maintain consistency and safety in aerospace manufacturing and maintenance.

Key Topics

• Scope and Purpose
  EN 4425:2006 applies specifically to tab washers used in flight control rods. These washers secure the rod end position while allowing necessary adjustment, a vital function in control rod assemblies.

• Dimensions and Masses
  The washers’ configuration must conform to specified dimensions illustrated in the standard's detailed tables and figures. Dimensions such as diameters, thickness, radii, and lengths are controlled with tight tolerances.

• Material Requirements
  The washers are manufactured from corrosion-resistant steel meeting EN 3488 standards, ensuring high durability and corrosion resistance suitable for aerospace environments.

• Surface Finish
  A surface roughness of Ra = 3.2 µm is mandated to reduce friction and wear during adjustment and operation.

• Designation and Marking
  Each tab washer is designated by a code including the standard number and diameter code. Markings on the washer and packaging ensure traceability without compromising component integrity.

• Qualification and Quality Management
  Compliance with aerospace quality management systems such as EN 9100 is required to guarantee manufacturing consistency and performance.

Applications

EN 4425:2006 tab washers are used within aerospace flight control systems, specifically:

• Flight Control Rod Assemblies
  Securing the rod end to the rod body in flight control linkages, preventing unwanted movement without restricting precise positional adjustments.

• Aircraft Maintenance and Manufacturing
  Ensuring standardized components enhance interchangeability, reduce assembly errors, and satisfy rigorous aerospace reliability requirements.

• Safety-Critical Aerospace Components
  The use of corrosion-resistant steel and tight dimensional control supports the high performance and safety demands of the aerospace industry.

These tab washers contribute directly to in-flight control accuracy and the overall safety of aircraft operation.

Related Standards

• EN 3488
  Defines the material grade for corrosion-resistant steel used in manufacturing the tab washers.

• EN 9100
  Specifies quality management systems tailored for aerospace manufacturing and design assurance.

• ISO 9001:2000
  Underpins the quality standards adapted in EN 9100 for general quality management principles.

Standards like EN 4425:2006 integrate with broader aerospace specifications to support high-reliability applications through standardized components and manufacturing best practices.

Keywords: EN 4425:2006, aerospace tab washers, flight control rods, corrosion-resistant steel, washer dimensions, aerospace standards, flight control system components, EN 3488 steel, EN 9100 quality management, aircraft maintenance components.