Ground Sikorsky helicopters until parts replaced: FAA

The U.S. Federal Aviation Administration has instructed owners of Sikorsky S-92A helicopters to cancel flights until they have replaced a component that has been associated with a fatal crash off Newfoundland.

The emergency directive was issued because of "the failure oftwo main gearbox filter bowl assembly mounting studs [that were] found broken during a fatal accident investigation in Canada," the FAA said in a statement issued late Monday.

The directive had been expected for days, since the Transportation Safety Board of Canada discovered a broken titanium mounting stud in the wreckage of a Cougar Helicopters aircraft that crashed into the Atlantic Ocean on March 12, killing 17 of the 18 people who had been aboard.

The TSB has emphasized that the finding of the broken stud does not necessarily mean itcaused the crash of the Cougar chopper, which had been ferrying workers to two offshore oil platforms off the east coast of Newfoundland.

Minutes before the crash, the crew reported mechanical problems involving the aircraft's gearbox. Investigators believe there was a sudden drop in oil pressure.

In its directive, the FAA noted that U.S.-based Sikorsky was "investigating a July 2008 incident that also involved broken studs. In both cases, the broken studs resulted in rapid loss of oil."

Sikorsky Aircraft Corp. had issued its own advisory on replacing the studs on Friday.

Sikorsky official Paul Jackson told CBC News on Tuesday that 59 of the 91 applicable aircraft have now been retrofitted.

"We expect to have close to 100 per centcompliance by the end of the week. Many operators are commending the speed with which they are receiving the parts and being able to install them," Jackson said in a statement to CBC News.

"It's important to emphasize that no final determination has been made as to whether the broken titanium studs contributed to the accident or were caused by it. As long as there was any possibility of the former, we immediately sent out our All Operators Letter," Jackson said.

Also on Tuesday, the TSB released photographs of the wreckage of the Cougar aircraft, most of which was retrieved from the floor of the Atlantic Ocean. It had been submerged under almost 180 metres of water.

The photographs bear out the descriptions of TSB investigators, who reported that the aircraft had sustained dramatic damages when it crashed on March 12.

Only one person survived the crash. Robert Decker, 27, remains in critical but stable condition at the Health Sciences Centre in St. John's. His family issued a statement on Monday saying that Decker, who worked as an ice tracker, had "turned the corner" and is now expected to make a full recovery.

It's not known how Decker, who was hoisted from the Atlantic Ocean shortly after the crash, and another worker, Allison Maher, wound up outside the helicopter. Maher died in the incident.

The bodies of two crew and 14 other passengers were all recovered later inside the fuselage, which was located about 55 kilometres east-southeast of St. John's.

Before recovering what they could of the aircraft's wreckage, TSB investigators pulled up the cockpit voice recorder and the flight data recorder.

The TSB said it will provide an update on its investigation on Thursday.