Sikorsky chopper grounded over gearbox crack

A Cougar Helicopters Sikorsky chopper has been grounded in St. John's because of a crack near the gearbox, CBC News has learned.

U.S.-based manufacturer Sikorsky said the crack is in a footing that attaches the main rotor's gearbox to the body of the aircraft.

The crack was discovered in the same S-92 helicopter that had been grounded in January with the same problem.

Cougar uses the helicopters to transport crews to fields working in the offshore oilfields east of Newfoundland.

In a separate incident, another Cougar helicopter was grounded in Halifax in November, after a hairline crack was found.

Public scrutiny of Cougar's aircraft has been high since March 2009, when a Sikorsky S-92 crashed into the Atlantic Ocean, killing 17 of the 18 people who were aboard. The Transportation Safety Board has not yet completed its investigation into the crash.

In a statement issued Thursday evening, Cougar Helicopters said it is complying with all directives and that the aircraft will go back into operation as soon as the "maintenance action" is completed.

"As this does not impact the safe operation of the aircraft, this is considered a standard maintenance action and completed as prescribed by the manufacturer (Sikorsky)," the Cougar statement said.

Sikorsky insists that the current issue is not a "flight safety issue," but the European Aviation Safety Agency has said that this problem could lead to loss of control of the helicopter.

Sikorsky said it will replace the gearbox as a precaution. That work was scheduled to start on Thursday. Sikorsky did the same thing after the January and November incidents.

Sikorsky said it is making better gearbox housings to resolve the issue.