The busy North Sea oil and gas rig transportation sector lost nearly a third of its capacity on October 23, after CHC Helicopter suspended all flight operations using the Eurocopter EC 225. The ban, pending further investigation, came after a company Super Puma ditched in the North Sea off the coast of Scotland the day before. CHC competitors Bond and Bristow also grounded their Super Pumas after the incident.

The UK’s Air Accident Investigation Branch has indicated that a cracked gearbox shaft appears to be a probable factor.

The CHC crew helicopter performed “a controlled ditching” 32 miles south of the island of Shetland at approximately 3:30 p.m. local time on October 22. All 17 passengers and both pilots aboard were rescued unharmed by a standby ship. The aircraft was traveling northeast from Aberdeen at the time of the incident.

The company says plans are already under way to recover the Super Puma, which remained floating at the time of the rescue.

CHC operates a fleet of more than 250 aircraft in 30 different countries. On October 26, the oil and gas industry’s Helicopter Safety Steering Group cleared AS 332L, L1 and L2 variants of the Super Puma to resume operations. This covers nine helicopters used in the North Sea, leaving 25 EC 225 aircraft still grounded.