30 CFR 250.511 - Traveling-block safety device.
All units being used for well-completion operations that have both a traveling block and a crown block must be equipped with a safety device that is designed to prevent the traveling block from striking the crown block. The device must be checked for proper operation weekly and after each drill-line slipping operation. The results of the operational check must be entered in the operations log.
Title 30 published on 2013-07-01
no entries appear in the Federal Register after this date.