ST. JOHN'S, N.L. - Families of the victims of a tragic helicopter crash off Newfoundland are putting pressure on Ottawa to act in the aftermath of a report into the accident.

The request comes in a lawyer's letter to Transport Minister Chuck Strahl on behalf of the families of the 15 passengers who died in the crash of Cougar Flight 491 in March 2009, as well as the sole survivor.

The Transportation Safety Board released its final report earlier this month, citing a number of factors in the crash of the Sikorsky S-92 including a severe loss of oil affecting the main gearbox.

The letter dated Feb. 18 calls on Strahl to investigate Transport Canada's initial certification the S-92 helicopter.

"While the TSB report is extensive and detailed in many respects, it does not satisfactorily address critical questions pertaining to the manner in which the Sikorsky S-92 helicopter was initially certified by Transport Canada ...." says the letter from the legal offices of Camp Fiorante Matthews.

The families also want Strahl to probe Transport Canada's response to an incident involving the same type of chopper in Australia in July 2008. In that case, pilots of the helicopter arrived safely on land after losing oil pressure to the main gearbox.

Strahl has asked his department to respond to the TSB's recommendations as soon as possible.

The families say they are looking for answers to questions about a number of issues in the interest of aviation safety and are not advancing a case for compensation.