Accession Number : ADP010187
Title : Failure Analysis of Modular Lift Link, Lug Mounting, Self-Locking Nuts
Corporate Author : ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
Personal Author(s) : Grendahl, Scott
PDF Url : ADP010187
Report Date : APR 1996
Pagination or Media Count : 13
Abstract : The U.S. Army Research Laboratory-Materials Directorate (USARL-MD) conducted a failure analysis of two self-locking nuts from an army attack helicopter, at the request of the U.S. Army Aviation and Troop Command (ATCOM). Light optical and scanning electron microscopy were utilized to characterize the fracture halves of the broken nuts. The self-locking nuts are governed by Specification MS21042, Nut, Self- Locking, 450 deg F, Reduced Hexagon, Reduced Height, Ring Base, Non-Corrosion Resistant Steel. During phase maintenance on the lift beam in the pylon area, maintenance crews noticed the bolts securing the lift link support lug were not properly seated. Further inspection showed that the left side self-locking nuts were cracked and/or missing. The right side nuts were also cracked.
Descriptors : *SYMPOSIA, *FAILURE(MECHANICS), *LOCKING FASTENER DEVICES, *NUTS(FASTENINGS), MAINTENANCE, ATTACK HELICOPTERS, SCANNING ELECTRON MICROSCOPES, HYDROGEN EMBRITTLEMENT, STRESS CORROSION, CHEMICAL ANALYSIS, METALLOGRAPHY.
Subject Categories : Attack and Fighter Aircraft
Properties of Metals and Alloys
Machinery and Tools
Distribution Statement : APPROVED FOR PUBLIC RELEASE