Transport Canada orders Boeing 737 jet operators to limit use of anti-icing system amid safety concerns

Airlines flying the 108 Boeing 737 MAX jets operating in Canada will have to limit the use of an engine anti-icing system to avoid possible catastrophic damage to engine housings, according to a new directive from Transport Canada. 

The change stems from a directive released by the Federal Aviation Administration (FAA) in the U.S., which was prompted by the results of in-flight tests that showed using the engine anti-icing system in dry air for more than five minutes in certain conditions can cause overheating and result in "severe engine inlet cowl damage." The system prevents ice from forming inside the engine during use.

The damage could result in parts of the engine cover coming loose, potentially causing damage to the fuselage and windows of the airplane. This could cause decompression of the cabin and pose a hazard to window-seated passengers behind the wing. The FAA says so far there have been no reports of these types of failures with planes in service. 

The planes are all equipped with the LEAP 1B engine made by CFM International, a joint venture between GE Aviation and Safran Aircraft Engines. 

The directive, which was published on Aug. 10, comes into effect on Aug. 25 and was issued under a provision that allows for immediate adoption of a new rule without providing notice or seeking comment prior to it being issued.

Transport Canada tells CBC News that they have "reviewed and accepted this Federal Aviation Administration Airworthiness Directive for Canadian registered aeroplanes, and it is applicable to Canadian registered products."

Directive latest issue facing 737 MAX jets

Of the 108 737 MAX jets in Canada, 40 are operated by Air Canada and two are under lease to Air Transat. Flair Airlines operates 18 737 MAX jets. WestJet and Swoop did not respond to the CBC before publication with the number of planes affected in their fleets.

Air Canada, WestJet and Flair Airlines acknowledged the directive and said the changes would not have any effect on passenger service. Air Transat is working with the lease provider of their two planes and also said that the changes would have no impact on their schedule.

The directive is just the latest issue faced by the 737 MAX, which Canadian airlines now refer to as the 737-8. The plane was grounded worldwide in 2019 after two crashes.

During the grounding, Boeing redesigned the plane's Manoeuvring Characteristics Augmentation System, which was blamed for two high-profile crashes. The FAA allowed the plane to return to service in 2020 and Transport Canada followed in 2021.