The Canadian national airline revealed a new technical problem facing the Boeing 737-8 MAX aircraft, two of which crashed in Indonesia 2018 and Ethiopia in 2019;
As a result, 346 passengers were killed.
The Canadian company said in an emailed statement that its Boeing 737-8 Max airliner encountered an engine problem during its flight from Arizona to Montreal, Canada.
The company explained that this problem forced the crew to divert the flight path to Tucson, Arizona.
A company spokesman said that the pilots had a light signal related to an engine failure shortly after take-off, and therefore, "they decided to stop one of the engines."
"The plane then diverted to Tucson, where it landed naturally and is still there," he added.
The incident goes back to December 22.
Aviation24.be, the Belgian aviation news site, said the flight crew had received a signal that the hydraulic pressure of the left-hand engine had decreased, and an emergency had been declared before the flight diversion.
"The modern aircraft are designed to operate with a single engine, and our crews are trained on such operations," the company’s statement added.
Boeing and airlines are preparing for an intense screening process as the MAX returns to service after a 20-month hiatus.
But safety experts say such a defect is common and usually goes unnoticed.
The MAX was decommissioned after two accidents partly related to defects in the cockpit software, and there was no connection with the engines.
The United States last month lifted a 20-month ban on operating flights of the 737 MAX aircraft, after the US Federal Aviation Administration specified details of software, systems and training updates that Boeing and airlines must complete before transporting passengers.