The Federal Aviation Administration (FAA) has issued in-structions for the inspection of Sikorsky model S-92 helicopters — the same helicopters used to ferry workers to and from the oil rigs off the coast of Newfoundland and Labrador — for a crack in the main gearbox.
The inspections, according to an airworthiness directive issued by the American regulator Tuesday morning, are to be conducted within 10 hours time-in-service or 15 days, whichever occurs earlier.
“This (directive) is prompted by an incident in which a crack in the main gearbox housing ... allowed a measurable amount of oil to leak from the main gearbox,” the FAA states.
“This condition, if not corrected, could result in loss of oil, failure of the main gearbox and subsequent loss of control of the helicopter.”
A spokesman for the manufacturer, Sikorsky, told The Telegram the single case referred to is from December 2011, when a gearbox housing on a single helicopter was found to have oil leaking at a very low rate.
The leak was the result of a “manufacturing anomaly,” according to the company.
The FAA’s directive, a company rep stated, was issued to mandate compliance with two existing service bulletins previously issued by Sikorsky. One, a call for daily inspection, was issued the day the single case of an oil leak was found.
The second was issued when the anomaly was discovered, he said, and it instructed technicians on how to check for the defect.
To date, “the inspections confirmed that the anomaly identified on the seeping main gearbox did not exist on any other inspected main gearboxes,” the Sikorsky spokesman stated in an email.
“The manufacturing process has been reviewed and improved to eliminate a possible repeat of the condition.”
The company had requested all checks for the anomaly be completed by June of this year. The FAA directive now requires the checks to be completed.
Cougar Helicopters has confirmed for The Telegram the helicopters being used in this province are checked and the company responds to all FAA directives applicable to the aircraft it operates.
“Cougar has one hundred per cent confidence in the airworthiness of its Sikorsky S-92 fleet of worldwide aircraft,” a spokeswoman for Cougar stated Tuesday.
On March 12, 2009, a Sikorsky S-92 with 16 passengers and two pilots crashed into the Atlantic Ocean while flying between St. John’s and this province’s offshore oil fields.
Seventeen people died and there was one survivor.
The crash of Cougar Flight 491 was the subject of a formal inquiry established by the Canada-Newfoundland and Labrador Offshore Petroleum Board, a separate investigation led by the Transportation Safety Board and lawsuits on behalf of the victims, subsequently settled.
The helicopter’s main gearbox lost oil during the flight and became a focus for response to the crash.
Sikorsky made modifications to the helicopter following the disaster, ultimately ordering a retrofit of the main gearbox for S-92s in use.
In March of this year, operator Cougar Helicopters sought a replacement of a main gearbox on one of its
S-92s because it had been recommended by the manufacturer to “fully ensure the fidelity of the gearbox,” according to a statement made at the time.
The Telegram has contacted Transport Canada in connection with this story and will provide any further information as it becomes available.
The American regulator’s directive was issued without the FAA having sought comments from Sikorsky or from current operators.
“We are issuing this airworthiness directive because we evaluated all the relevant information and determined the unsafe condition described previously is likely to exist or develop in other helicopters of the same type design,” it states.
Over 150 Sikorsky S-92s are operated in more than 24 countries worldwide.