Failure Analysis to Directional Control Pedal Assemblies of a Crashed Helicopter

Technical Article---Peer-Reviewed
  • 97 Downloads

Abstract

In investigation to a helicopter crash accident, a pedal for pilot’s yaw control input was found to be separated from pedal pivot arm by fracture through two fillet welds. Fractographic and metallurgical studies were carried out on these two welds. Fatigue striations on the fracture surfaces of the welds were found and the failure was determined to be result of fatigue of the two welds. Furthermore, weld defects including insufficient weld leg, incomplete fusion, overlap on the base metal and porosity were found and evaluated against applicable standards. It was concluded that the welds were not in compliance with the standards and are root cause of the fatigue fracture. Recommendations of revising manufacturer’s production specification and/or redesigning the assembly were made.

Keywords

Fatigue Aluminum alloy Argon arc welding Weld defect Helicopter 

References

  1. 1.
    AWS A3.0-2010: Standard Welding Terms and Definitions. American Welding SocietyGoogle Scholar
  2. 2.
    Properties and Selection: Nonferrous Alloys and Special-Purpose Materials, ASM Handbook, vol. 2, 10th edn. American Society for Metals (1990)Google Scholar
  3. 3.
    AMS 2658C: Hardness and Conductivity Inspection of Wrought Aluminum Alloy Parts. Society of Automotive Engineers (2009)Google Scholar
  4. 4.
    ASTM E 1004-02: Standard Practice for Determining Electrical Conductivity Using the Electromagnetic (Eddy-Current) Method. American Society for Testing and Materials (2002)Google Scholar
  5. 5.
    MIL-STD-2219A: Fusion Welding for Aerospace Applications. Department of Defense (2005)Google Scholar

Copyright information

© ASM International 2011

Authors and Affiliations

  1. 1.China Academy of Civil Aviation Science and TechnologyBeijingChina

Personalised recommendations