MONTREAL - Update: Air Canada announced on Monday evening that it will extend a $15 million line of credit to Aveos.

"This stabilization should allow Aveos to reopen certain facilities and call back certain employees, giving Air Canada the confidence to add new maintenance work over the next days and weeks," the airline announced.

Air Canada is once again facing disruptions and labour disputes, this time after a company that provides maintenance for the airline announced it was laying off 2,400 employees across Canada.

Hundreds of Aveos employees rallied on Monday morning on Cote Vertu Blvd. near Trudeau Airport, blocking access to Air Canada headquarters.

They were upset that Aveos abruptly announced on Sunday that it was shutting down plants in Vancouver, Winnipeg and Montreal.

"I got called yesterday at 5 o'clock by my manager," said aircraft technician Rehan Sheikh. "He said Aveos has closed down, been shut down."

Roughly 1,800 employees work at the Montreal aircraft maintenance plant, a thousand of whom protested in Montreal Monday morning.

Aveos was created by Air Canada in 2007 when the airline restructured and decided to spin off its maintenance division into a standalone company.

Union representatives say many employees were still being paid by Air Canada until just a few months ago.

"The 18-hundred people that work here in Montreal and the 3,000 around the country, these employees were employees who built Air Canada," said Marcel St-Jean. "They were all Air Canada employees before the 31st of December 2011. It's not even three months that they're losing their jobs after that."

Bankruptcy protection

On Monday Air Canada issued a statement saying that Aveos had filed for bankruptcy protection, which caught employees by surprise.

"It was pretty traumatising to get informed like that. At least give us a two-week notice," said Sheikh.

The news outraged Liberal MP Denis Coderre.

"I'm pissed off today that's for sure and I believe that Aveos should bring some answer to their employees," said the Montreal-area MP. "The savage way they have been treated is unacceptable."

Air Canada said it has contingency plans in place in the event that Aveos is no longer able to perform maintenance on airplanes.

That did not impress Aveos employees.

"It's terrible what is happening. What is Air Canada doing to its employees," said St-Jean.

Flights grounded over weekend

The layoffs come after a weekend of when flights, mostly out of Montreal, were cancelled or delayed when several pilots called in sick.

The airline appears to be back to business as usual Monday, although the departure schedule posted on the Greater Toronto Airport Authority website showed Air Canada flights to Ottawa, Montreal, Winnipeg and Seattle were all cancelled Monday. No other airline indicated cancellations.

Just last week the federal government passed back-to-work legislation intended to prevent labour disruptions at the airline, after Air Canada threatened to lock out pilots and ground crew unions negotiated for a new contract.

If the higher-than-normal number of pilots calling in sick was intended to send a message, aviation analyst Karl Moore says that's done. Now, he expects a cooling off period as the CIRB considers Air Canada's complaint.

"My sense is it will calm down from this point on," said the McGill University business professor. "They've got to deliver good service," he said. "That will be the best calming thing."

The CIRB can levy fines if it determines absences due to illness were in fact job action.

Aveos employees worried in 2009

Workers at Aveos have worried for years that their jobs would be shipped overseas.

In 2009 about 1,000 aircraft maintenance workers staged a one-day protest at Air Canada HQ out of worries the company would send more work to El Salvador.

At that time time Aveos had three hangars in Canada and capacity at a fourth plant in El Salvador was being expanded to work on up to 16 planes at a time.

Union executives at that time were also worried about their pension plan, saying it was billions of dollars in debt.

With files from the Canadian Press