While washing down the 7” liner assembly on 5 ½” DP which weighed 364,000 pounds (total l65 metric T) in open hole the Driller heard a loud bang. This was immediately followed by loss of the electric auxiliary brake’s control over the assembly’s descent. The Driller vigorously applied the manual brake to slow the descent and called for the slips. The string descended approximately 52 ft (16 m) before a Floorman managed to set the slips. The blocks came to rest about 28 ft (4.6 m) above rotary table.