SIST EN 4050-4:2014

Overview

The SIST EN 4050-4:2014 standard is part of the Aerospace series established by CEN, focusing on the ultrasonic inspection of metallic materials such as bars, plates, forging stock, and forgings. Specifically, this standard sets out the acceptance criteria for such products after ultrasonic testing as per EN 4050-1. Its purpose is to define clear, uniform acceptance levels to ensure material integrity and safety in aerospace applications.

This standard is essential for manufacturers, quality control engineers, and inspectors involved in aerospace material testing. It provides a consistent framework for interpreting ultrasonic inspection results with emphasis on defect detection and categorization.

Key Topics

• Scope and Application
  EN 4050-4 specifies the acceptance criteria following ultrasonic inspection methods outlined in EN 4050-1. It applies to metallic aerospace materials including bars, plates, forging stock, and forgings.

• Acceptance Criteria Classes
  The standard introduces seven classes (1 to 7) defining maximum permissible discontinuities, both single and multiple, measured by Full Beam Height (FBH) in millimeters:

  • Single and multiple defect limits are categorized by class
  • Limits control both linear and non-linear indications seen on ultrasonic inspection
  • Defect spacing and size thresholds are clearly specified to reject unacceptable materials

• Inspection Techniques
  The choice of ultrasonic inspection techniques depends on the class of product:

  • Classes 1 to 6: immersion, mechanized contact, or manual contact inspection methods
  • Preferential use of immersion or mechanized contact for classes 5 and 6, ensuring precise defect detection
  • Class 7 inspection involves immersion or mechanized contact for sheets, bars, and forged parts

• Evaluation Parameters
  Alongside size limits, the standard restricts:

  • Loss of back wall echo (a key ultrasonic response) measured either in dB/mm or as a screen height percentage
  • Noise levels during inspection, which must remain below the designated monitor threshold

Applications

• Aerospace Material Quality Assurance
  EN 4050-4 is widely used by aerospace manufacturers to validate the quality of metallic billets, bars, plates, and forged components meeting strict aerospace safety regulations.

• Non-Destructive Testing (NDT) Procedures
  Ultrasonic inspection stakeholders utilize the acceptance criteria to determine if a part meets specifications or requires rejection or rework, guaranteeing structural integrity.

• Supplier and Vendor Compliance
  Raw material suppliers in aerospace industries adopt EN 4050-4 acceptance criteria to certify that materials delivered to manufacturers conform to aerospace standards.

• Inspection Technique Optimization
  Enables aerospace quality inspectors to select appropriate ultrasonic testing methods aligned with product classes, enhancing inspection efficiency and reliability.

Related Standards

• EN 4050-1: Provides the general requirements for ultrasonic inspection methods applied to aerospace metallic materials, serving as the technical foundation for EN 4050-4 acceptance criteria.

• ASD-STAN Aerospace Standards: EN 4050-4 is developed by the Aerospace and Defence Industries Association of Europe (ASD-STAN), aligning with other aerospace material and testing standards.

• Other Ultrasonic NDT Standards: While EN 4050-4 focuses on aerospace, it complements international ultrasonic testing guidelines used in various industries, ensuring harmonized quality controls.

By following SIST EN 4050-4:2014, aerospace industries maintain high reliability and safety standards in metallic components through rigorous ultrasonic inspection and defined acceptance criteria. This standard is invaluable for consistent quality assurance, advancing the structural integrity of aerospace materials globally.