While the American South hunkers down and waits for this week’s blast of snow and icy temperatures to dissipate, a crew of aviation engineers up in central Canada is hoping for just the opposite. “We love subzero weather, and pray for it,” says Eric Hegedus, an engine test engineer with GE Aviation. “It’s the definition of insanity.”

Insanity that keeps your plane safe in the nastiest of weather. Hegedus and his colleagues are temporarily stationed at GE’s Aircraft Engine Testing, Research, and Development Centre, in Winnipeg, Manitoba, where winter temperatures average around 10 degrees Fahrenheit. They’re here to bring the freeze to the world’s largest jet engine, the GE9X.

Developed primarily for the new Boeing 777X, this behemoth is wider than the fuselage of a 737 jet and can generate more than 100,000 pounds of thrust. It wields a 134-inch-wide fan, and is now in late-stage development for its new aircraft. Hegedus, who usually works at GE Aviation’s Cincinnati headquarters, is in Winnipeg to see how well the engine handles when things get icy.

Just to mount the ginormous thing, which just completed other tests (like being shot with bird carcasses and consuming buckets of foreign sand) at GE’s Peebles, Ohio, facility, the team had to expand and rejigger its test stand, rigging up extra fans and nozzles, to simulate the amount of air and water the engine will guzzle at speed.

Once they’ve installed and wired up the engine with a bevy of sensors, the engineers will sit and wait for the right temperature to arrive—somewhere between -6 and -10 degrees Fahrenheit. “We get the coldest weather here at night, of course, so we’ll be on-call 24 hours a day,” Hegedus says. “We might work from 6 pm to 8 in the morning, running the engine through the data points we need to evaluate.”

The tests aren’t meant to simulate high-altitude conditions—the air 30,000 feet up is far colder than anything Canadians suffer—but rather the various kinds of clouds the engine will encounter during ascents and descents, where the air is moist and icing most frequently occurs. The team runs the engine at different speed levels, representing different stages of flight and shoots it with streams of vapor at a range of widths and densities, to simulate the kinds of clouds the airplane might encounter in cold weather.

You might think the planet’s biggest engine runs hot enough to vaporize any ice bold enough to get near it. In fact, apart from the core, most of the engine is cold, including the elements right behind the fan. Ice can accumulate on the spinner cone in front of the fan or on the GE9X’s sixteen enormous blades. That extra weight can throw the engine off balance, or make the blades rub up against the fan case, abrading either. Ice can also form inside the bypass area—the interior wall of the duct surrounding the engine, through which air passes before it’s accelerated out the rear—and on the outside of the core.

Ice formation is inevitable in lots of flight conditions. These tests ensure the engine can tolerate it and continue to run smoothly long enough for the aircraft to pass through the conditions, or for the ice to simply slough off. (Pilots and the engine’s computer can also make changes to the engine speed to mitigate the likelihood or impact of ice formation.)

The GE9X went through engineering tests several years ago (aviation innovation is a lengthy process), so at this stage, the engineers don’t expect much more than minor modifications to how the engine responds to certain conditions. “We’ve applied all the best practices about how to handle ice accretion based on our experience and previous testing, so we expect this to be a smooth process,” Hegedus says. “It should pass on the first try.”

The testing window for the engine will run until about April (Manitoba stays cold late into the year). But if Hegedus and his team get lucky, maybe Old Man Winter will land on Winnipeg and let them knock out their work far sooner than that—so they can hop a safe flight back to the land of warmth.

More Big Ole’ Engines