Dome shutter failure causes longest shutdown (67-nights) ever recorded by CFHT Observatory

The dome shutter drive system for the CFHT observatory experienced two, separate, catastrophic failures recently (15 DEC 11) and (14 APR 12); leading to a full-blown, company-wide investigation to understand and determine the root cause of both failures. Multiple resources were utilized to detect and reveal clues to help determine the cause of failure. Former colleagues were consulted, video footage investigated, ammeter plots dissected, solid models developed, forensic analysis of failed parts performed, controller mock-up established; all in an attempt to gather data, better understand the system, and develop a clear path solution to resurrect the shutter and return it to normal operation. My paper will attempt to describe in detail the problems encountered, investigations performed, analysis developed, and solutions integrated.