View all text of Subjgrp 87 [§ 250.400 - § 250.409]
§ 250.404 - What are the requirements for the crown block?
You must have a crown block safety device that prevents the traveling block from striking the crown block. You must check the device for proper operation at least once per week and after each drill-line slipping operation and record the results of this operational check in the driller's report.