Failure Analysis of a Cracked CH-47 Swashplate Rotating Ring, S/N BCW-1379

Report No. ARL-TR-3826
Authors: Scott Grendahl; Russell Yocum
Date/Pages: June 2006; 28 pages
Abstract: The U.S. Aviation and Missile Command sent the U.S. Army Research Laboratory?s Weapons and Materials Research Directorate three swashplate rotating rings from the CH-47 helicopter for investigation. The components were examined due to the presence of cracks found during routine overhaul. These cracks were on and adjacent to the bearing retention shoulder. One of these rotating rings, S/N BCW-1379, was included for a detailed failure analysis to determine the cause of the cracking. This component was QDR exhibit number W45N7V-04-0307. The components were required to be forged from aluminum alloy 2014-T6. The focus of this investigation, BCW-1379, was characterized by ondestructive inspection, chemical analysis, optical microscopy, scanning electron microscopy, and mechanical testing. The holes of the rotating ring were numbered 0?36 around the perimeter, consistent with the convention of the MELRs from Boeing helicopters.
Distribution: Approved for public release
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Last Update / Reviewed: June 1, 2006