Less than two months before a twin-engine Beechcraft King Air 100 crashed in Richmond, B.C., killing the pilot and injuring eight others on board, American aviation officials issued an emergency air worthiness directive for the same type of engine that was in the downed plane.

But a spokesperson for Northern Thunderbird Air said its plane had been inspected, and was not operating with the affected faulty engine part.

General manager Bill Hesse said his company received the U.S. Federal Aviation Administration's Sept. 15th emergency directive on Sept. 16.

"We had all of our planes inspected and they were compliant by the 23rd," Hesse said.

"And just to be clear, the series of parts that were at issue in this directive were not found on our aircraft at all."

The U.S. Federal Aviation Administration (FAA)'s directive required owners and operators of several Pratt & Whitney Canada engine models to replace gear assemblies that may have been serviced since Feb. 3, 2010 using faulty replacement parts.

The U.S. Federal Aviation Administration (FAA) issued the directive in mid-September. It gave required owners and operators of several Pratt & Whitney Canada engine models 15 days to replace gear assemblies that were serviced since Feb. 3, 2010 using a specific faulty line of replacement parts.

"We are issuing this AD [airworthiness directive] to prevent failure of the shaft portion of the sun gear, which would result in an engine in-flight shut down, possible uncontained engine failure, aircraft damage, and serious injuries," the FAA wrote in the directive.

The FAA estimated that 5,000 planes in the U.S. alone would have to be inspected, but only 40 or 50 of them would need the gearboxes changed.

It said that 80 gearbox replacement parts are suspected of being defective due to a "manufacturing anomaly," and about half of those had already been taken out of service by Sept. 15.

Plane suffered 'engine oil' problem

NT Air Flight 204, bound for Kelowna, B.C., on Thursday had turned back shortly after departing from Vancouver after an indicator light alerted the pilots that there was a problem with one of the engines.

A note written by Transport Canada officials into its aviation incident database says that "the left engine oil pressure gauge showed fluctuations."

The aircraft did not make it back to the airport and crashed on Russ Baker Way in Richmond, about 900 metres short of the runway. The plane burst into flames shortly after it crashed and the pilot, Luc Fortin, died hours later in hospital.

Bill Yearwood, an official with the Transportation Safety Board said it's far too early to determine if any faulty part played a role in the crash of a plane in Richmond, but investigators will be considering all possibilities.

"We're exactly at that stage where we are identifying equipment in the plane. We will have manufacturers with us as we disassemble components that make up the aircraft," he said.

The Beechcraft 100 was built in 1970 and was using a Pratt & Whitney Canada PT6A-28 engine, according to Transport Canada records available online.

Transport Canada records also indicate that Northern Thunderbird Air had owned the plane, with mark GXRX, since 2006.

With files from the CBC's Bob Keating