A winter’s day in Winnipeg is a far cry from the stormy tropics. But for Brent Ostermann that makes it the perfect place to wreak havoc on aircraft engines in a way that could prevent disaster thousands of feet up and half a world away.
“What we’re testing for is how ice buildup can happen … and how that ice is shed,” said Mr. Ostermann, program director for a Winnipeg-based facility that specializes in freezing jet engines while they are in full throttle.
The idea that chunks of ice as large as 15 centimetres can grow on and then flake off a fan blade spinning inside a jet engine at 5,000 revolutions a minute is hard to imagine. But it has increasingly come to be recognized as a genuine hazard in the aviation industry, particularly at latitudes closer to the equator where massive storms can produce the high-altitude ice crystals that are thought to be the cause of the problem.
Now, a meteorological report that points to engine icing as a possible factor in the crash of AirAsia Flight 8501 is throwing a spotlight on an active field of research, including the Canadian site that was built specifically to re-create the phenomenon and test how new engine designs respond.
Opened by General Electric just two years ago, the Winnipeg facility is too recent to have been involved in the testing of the engine design used on AirAsia’s Airbus A320-200, which had 162 on board. But it is currently conducting tests on a design that is slated for a new generation of A320s – along with virtually every other engine General Electric is working on – with the goal of seeing how each engine responds to icing.
For proprietary reasons, Mr. Ostermann is circumspect about exactly how the ice buildup is accomplished, though the cold Manitoba air is a key ingredient.
“Sometimes we want to see if the engine is going to stall, because then we learn,” he said. “But to pass the test, the engine needs to keep flying.”
More than 200 examples of ice-induced “power-loss” have been reported in the past quarter-century, with at least one aircraft gliding into a “dead-stick” landing, without any power, its pilots unable to restart the engines. Most of the incidents have occurred in the south-east Asia region, near large convective storms like the ones AirAsia Flight 8501 encountered on its flight path Dec. 28.
It is not known what caused the jet to crash into the Java Sea, though Indonesia’s Meteorology, Climatology and Geophysics Agency said Sunday that bad weather could have been a “triggering factor.”
“The most probable weather phenomenon was icing which can cause engine damage due to a cooling process,” said a report from the agency, which added this was just one of the possibilities of what happened to the doomed jet.
On Monday, better weather allowed ships and divers to resume efforts to recover bodies and continue their search for Flight 8501’s black boxes. Until the digital flight data and cockpit voice recorders are found, it remains impossible to conclude with certainty what happened to the plane.
But what is clear from research like that done at GE’s Winnipeg site is that under the right conditions, the core of a jet engine that normally operates at hundreds of degrees Celsius can be so badly frozen it slows, or shuts down altogether.
This kind of icing involves clouds of ice particles, some as small as a grain of flour, and is different from the traditional kind of wing and engine icing that Canadian flyers are familiar with, after seeing aircraft sprayed with a chemical solution to prevent problems in wintertime.
Unlike thunderstorms, ice particles are largely invisible on aircraft radar and can be located as far as 50 kilometres from a cloud mass. They don’t crust wings with ice and don’t trigger aircraft ice detectors, making them even harder to spot. They aren’t even always associated with the worst possible weather: Pilots who have encountered them have said their flight conditions were unremarkable, with only light turbulence and something that looked like rain, when engines suddenly shut down.
Industry and government began studying the problem a decade ago, after a raft of unexplained losses of power – some of them severe, including one where the pilot re-started engines only 1,300 feet above the ocean.
It remains unclear precisely how ice-particle icing happens, however, or how to prevent it. Scientists, including some from Environment Canada, have used a Gulfstream business jet to look for ice particles off the coast of Australia, but that is expensive work – and difficult. The particles can act like a sandblaster on measuring instruments. The National Research Council in Ottawa has also done lab tests on ice particles, and major manufacturers have done their own research; Airbus itself has flown an A340 on numerous flights to collect data.
It wasn’t until 2013 that a specialized NASA research facility in Ohio was able to recreate the high-altitude icing conditions that shut down a running test engine. But the pace of discovery remains slow: “The fundamental physics of that we don’t really know,” said Michael Oliver, a research engineer who has led the NASA ice-particle tests.
Until recently, no rules have existed mandating that aircraft makers test their product’s ability to withstand ice particles. The first such rule was published by the Federal Aviation Administration in November, 2014, and will apply only to new aircraft. Europe has yet to issue its own rule; a $32-million EU-sponsored research project is not expected to finish until 2016.Report Typo/Error
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