46 CFR §134.150

1. (a)For this subchapter, liftboat jacking systems are vital systems and must comply with Sections 4/1.13.1 through 4/1.13.3 of the ABS's “Rules for Building and Classing Mobile Offshore Drilling Units” as well as meet the applicable requirements of part 128 of this subchapter.
2. (b)Each control system for a liftboat jacking system must be designed so that loss of power, loss of pressure in the hydraulic system, or low hydraulic-fluid level will activate a visible and audible alarm at the operating station and will not result in the liftboat's uncontrolled descent.