An investigation into a deadly crash involving an RCMP helicopter near Vancouver two years ago has prompted the Transportation Safety Board to warn that more than 500 similar aircraft across the country are at an increased risk when taking off in cold weather.
The board's report notes procedures for clearing water, snow and ice from the aircraft's engine system weren't followed, despite more than a decade of warnings from the manufacturer, and the board says it's concerned other pilots may not fully understand the risks or be following the proper procedures to mitigate them.
The safety board released a report Wednesday into a January, 2012, crash on Department of National Defence land at Cultus Lake, about 100 kilometres southeast of Vancouver. The pilot died.
The Eurocopter AS350 was in the area conducting training exercises in light snow, with temperatures around -10 C. Heavy snow covered the aircraft during a lunch break. Exercises were cancelled for the rest of the day and the pilot lifted off to return to Vancouver's airport.
"Soon afterward, there was a muffled bang and a puff of grey/white vapour from the exhaust area," the report says.
"At the same time, the customary and familiar sounds from the engine rapidly disappeared, and the regular slapping sound of the rotor blades quieted significantly." The helicopter fell rapidly and hit the ground nose-first, fatally injuring the pilot, who was described as "highly experienced and competent."
The investigation determined water, snow and ice had built up in the helicopter's engine air-intake system, in part because protective covers were not installed when the aircraft was left outside in the snow. When the pilot prepared for takeoff, the system wasn't properly inspected and the buildup wasn't cleared.
France-based Eurocopter and its predecessor, Aérospatiale, issued warnings as far back as 1985 that even small amounts of water can cause the engine to flame out, particularly after takeoff.
Eurocopter has recommended a number of measures to reduce the risk, such as the installation of protective covers and preflight inspections to detect and clear water, ice and snow.
But the Transportation Safety Board report says Eurocopter's most recent warning before the crash, in 2011, didn't appear to be widely distributed to RCMP pilots, though it was included in the aircraft's operations manual.
Such an inspection is complicated and isn't practical for pilots and crews to complete in the field, the report says.
Further, the board says its investigation revealed pilots in various commercial operators across the country appeared to be unaware of the safety notices or misunderstood the nature of the risk.
There are more than 500 Eurocopter AS350 and EC130 helicopters with the same engine intake design in use across Canada.
The board says it held a meeting of AS350 operators, with eight from B.C. attending. "None were aware that ice could form in the plenum between the filter and the engine," the report says.
Transport Canada is currently reviewing the design of the helicopter's engine inlet design.
The safety board report says the RCMP has taken numerous steps since the crash to ensure pilots and crews are aware of the risks and procedures related to operating Eurocopter helicopters in cold weather with the presence of water, ice and snow.
Immediately after the crash, the force issued a reminder to all pilots about the requirements for clean aircraft and were directed to review all operating manuals.
Pilots now receive cold weather and warm weather briefings before the start of each season.