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Canada is making changes to the way it approves new aircraft in the wake of the Boeing 737 Max disasters, and will look to close key regulatory gaps that allowed the plane to escape proper scrutiny before it was cleared to fly.

Senior Transport Canada officials said Ottawa is working with the U.S. Federal Aviation Administration to target regulatory blind spots that resulted in design flaws going undetected.

“You could call them loopholes that were taken advantage of,” David Turnbull, Transport Canadas’s director of National Aircraft Certification, told a House of Commons committee hearing Tuesday night.

In particular, Transport Canada officials are zeroing in on FAA regulation 21.101-1B, otherwise known as the Changed Product Rule. It states that any alterations to a new aircraft model that are significant enough to alter how it operates require the plane to be certified as an entirely new design.

However, when Boeing was bringing the 737 Max to market in 2017, the company was in a battle with rival Airbus to sell the newer fuel-efficient model, and wanted to avoid triggering an onerous certification process. Despite installing complex software on the aircraft that changed how it operated, Boeing withheld key details about the design from regulators.

A 737 Max crashed off the coast of Indonesia in October, 2018, killing 189 people, after the plane’s new software forced it into an irreversible nosedive. Five months later, another 737 Max fell from the sky in Ethiopia, killing 157 people, including 18 Canadians. In both cases, the software, known as the Maneuvering Characteristics Augmentation System, or MCAS, was found to be at fault by crash investigators.

A Globe and Mail investigation detailed how Boeing had misrepresented the software’s functions to regulators to skirt the Changed Product Rule, which allowed the Max to be cleared as a new iteration of a 737, rather than a completely different aircraft design. The Globe investigation also showed that in 2001, the FAA knew that the Changed Product Rule was flawed, since it was open to “varying interpretations” by aircraft designers, who treated the rule subjectively.

Mr. Turnbull told the hearing that Transport Canada and the FAA are tightening that rule. “We are going to be working with the FAA,” he said.

Under international agreements, new Boeing aircraft designs are certified by the FAA, while Transport Canada validates the U.S. regulator’s work to see whether there are any areas the federal government wants to investigate further on its own. Mr. Turnbull said Transport Canada was in the dark on the MCAS software, because details of how it operated hadn’t been fully revealed to the FAA.

“The full functionality of MCAS was not disclosed to us,” Mr. Turnbull said. “Clearly there was an information breakdown in the process between Boeing and the FAA, which we ended up getting caught up in when we came to do our validation. That’s the main concern.”

Mr. Turnbull called the Changed Product Rule “one of the most prominent” regulatory issues that needs to be addressed. Transport Canada officials said there are several changes to how aircraft are scrutinized that are being looked at, though some of those details have not yet been finalized.

“Our validation process will be much more thorough in a number of different areas,” Nicholas Robinson, director of civil aviation for Transport Canada, told the committee hearing.

The 737 Max was removed from service after the second crash in early 2019, and stayed grounded for nearly two years. It was only recently cleared to return in several countries, including Canada, after design changes by Boeing and a revamp of the MCAS software.

Transport Canada has also required additional measures to be put in place before the plane returned to Canadian skies, such as extra pilot training and the ability to disable a cockpit alarm in the event it is being fed erroneous information by sensors. Mr. Robinson and Mr. Turnbull both said they believe the problems with the Max have been fixed and the plane is safe.

However, Gilles Primeau, an expert in flight control systems, told the hearings in November that he believes the plane needs closer scrutiny. Boeing installed larger fuel-efficient engines that had to be repositioned on the wing. This changed how the plane flew, causing it to pitch up in certain cases. The MCAS, relying on a sensor that measures the plane’s angle of attack, then pushes the nose down to correct this. Some pilots have told The Globe the 737 Max’s aerodynamics make it less stable, while other pilots have disputed this argument.

The debate over the 737 Max has found its way into the hearings several times, including on Tuesday when Mr. Turnbull and Mr. Robinson took issue with a guest column in The Globe in January, written by Brian Barsky, a professor of the Graduate School in the College of Engineering at the University of California, Berkeley. Mr. Barsky, who teaches a course on the 737 Max, argued among other things that the plane’s design changes made it unstable compared with older 737 models. Mr. Turnbull called this “simply untrue” and “false.”

Reached Tuesday night, Mr. Barsky said he wasn’t clear what the Transport Canada officials were alleging was incorrect. “Is David Turnbull saying that it is not true that the 737 MAX has a propensity under certain conditions to pitch up and that [the angle of attack] sensor data is used to automatically engage MCAS to adjust the horizontal stabilizer trim and push the nose down?”

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