U.S. ban on helicopter part involved in N.W.T. crash extends to Canadian operators

A recent U.S. ban on a helicopter part involved in a crash in Fort Good Hope, N.W.T., earlier this year also affects Canadian operators, according to Transport Canada.

The U.S. Federal Aviation Administration (FAA) recently issued an airworthiness directive calling for operators to replace a specific tension torsion (TT) strap for several Bell helicopter models. The directive also prohibits the future installation of those straps.

The directive calls for operators to replace any straps with more than 350 flying hours, within an additional 50 flying hours. Any straps with fewer than 350 flying hours should be replaced before they hit 400 total hours.

The strap in question is manufactured by Airwolf Aerospace. In its preliminary findings, theTransportation Safety Board of Canada determined this type ofstrap was involved in the crash that claimed the life of pilot Tom Frith near Fort Good Hope this summer.

Transport Canada says the FAA ban extends to Canadian operators as well. In an email, Sau Sau Liu, a senior communications adviser with Transport Canada, explained that the FAA was the original organization to approve the straps, therefore Canadian regulations defer to that organization for this directive.

She said that's also why Transport Canada did not issue its own directive.

"Owners and operators of those helicopters with affected TT straps are required to comply with the actions mandated in the FAA AD [airworthiness directive] and therefore, by regulation, a Transport Canada AD is not required," she said.

Safe but costly

Tension torsion straps are what connect a helicopter's rotor blades to the rotor head.

"So [if]one of them lets go, you've only got three blades andcompletely unbalanced and, of course, it will inevitably crash," said Jock Williams, an aviation expert and former safety officer with Transport Canada.

Williams commended the FAA for its directive but also recognized it'll come at a cost for companies.

"I'm a believer that the United States is doing a safe thing, but it may be a horrendously expensive thing," he said.

In its directive, the FAA said the removal and replacement of the straps would affect about 120 registered American aircraft. It estimates that operators would have to replace two straps and cost $18,850 US per helicopter.

CBC has asked Transport Canada how many aircraft it expects would be affected by the directive.

The FAA's directive comes into effect on Oct. 11.