Accession Number : ADP010186

Title :   Failure Analysis of a Pitch Link Self-Locking Nut MS 17825-10

Corporate Author : ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD

Personal Author(s) : Grendahl, Scott

PDF Url : ADP010186

Report Date : APR 1996

Pagination or Media Count : 13

Abstract : The Aviation and Troop Command (ATCOM) shipped a broken self-locking nut to the Army Research Laboratory-Materials Directorate (ARL-MD) and requested a metallurgical investigation to determine the probable cause of failure. The component was received on 31 October 95, hexagon shaped, castellated self-locking nut, MS 17825-10, was attached to the lower end of the pitch link located on an army attack helicopter. The outside of the nut contained the manufacturer's designation which consisted of the letter 'G' stamped 5 times along a longitudinal section of the part. The nut was fabricated from non-corrosion resistant steel and is to he used at temperatures up to 250 deg F. During assembly while applying torque, the nut cracked and split open. Further inspection revealed that the nut was cracked at one of the castellations.

Descriptors :   *SYMPOSIA, *FAILURE(MECHANICS), *LOCKING FASTENER DEVICES, *NUTS(FASTENINGS), ATTACK HELICOPTERS, MECHANICAL PROPERTIES, SCANNING ELECTRON MICROSCOPES, CHEMICAL ANALYSIS, TORQUE, METALLURGY.

Subject Categories : Attack and Fighter Aircraft
      Properties of Metals and Alloys
      Machinery and Tools

Distribution Statement : APPROVED FOR PUBLIC RELEASE