An Air North flight had to return to Vancouver this week after its electrical system failed.
On Monday, an Air North Boeing 737 was en route to Whitehorse when a circuit breaker tripped.
Multiple electrical failures occurred while the airplane was climbing, according to a Canadian Transportation Safety Board report on Wednesday.
The crew completed its checklists and found a transfer bus circuit breaker had tripped.
“The procedure is you can reset a circuit breaker once, which they did,” said Air North president Joe Sparling.
But 10 minutes later, it tripped again.
The flight had reached cruising altitude and was 351 kilometres north of Vancouver when it tripped the second time.
The circuit breaker was for a bus bar that provided power to some fairly essential systems, including flight instruments, the autopilot and the automatic cabin pressurization, said Sparling.
“So when that happens you have to turn around and land as soon as you can.”
The plane turned around and headed back to Vancouver.
The electrical failure didn’t interfere with the flying of the plane, said Sparling.
“There is redundancy for all of those things, but you can’t rely on redundancy to carry on to your destination.
“When something like that happens you have to land fairly promptly.”
The plane burned off fuel and landed about 75 minutes after it lost its electrical system.
During the descent, the cabin altitude horn activated. But the crew completed its checklist and was able to regain control of the cabin pressure.
It’s not the most serious thing that’s ever happened, said Sparling.
But it was an “unusual and unique problem.”
Air North, which has four 737s (the newest a 737-400), was able to reassign its flight relatively quickly.
The malfunctioning Boeing 737-200, which was built in the 1980s, spent all day Tuesday on the ground while they were troubleshooting the problem, said Sparling.
“They couldn’t duplicate the problem on the ground, and they did a test flight and changed the circuit breakers.
“They believe it was probably a faulty circuit breaker,” he said.
“The plane flew last night and its flying again tonight and we haven’t had any further issues with it.”
Contact Genesee Keevil at gkeevil@yukon-news.com