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By Murray Brewster, THE CANADIAN PRESS
OTTAWA - Two of the navy's aging Sea King helicopters suffered debilitating engine fires on the same day aboard different warships under circumstances that flight safety investigators are at loss to explain.
A preliminary investigation suggests the No. 2 engines on both aircraft overheated because they were inexplicably sprayed with fresh water, clogging air compressors with ice.
Why it happened on two ships - dozens of kilometres apart - within hours of each other is the subject a continuing probe.
"I'm baffled with that question myself," Capt. Katherine Ashton, a former Sea King pilot and currently a flight-safety investigator, said Monday.
The mysterious incidents, which took place aboard HMCS Charlottetown and HMCS Athabaskan on March 7 last year, are detailed in documents obtained by The Canadian Press under the Access to Information Act.
Both warships were part of a naval exercise off southern Nova Scotia and were accompanied by the supply ship HMCS Preserver, according to an incident report filed the day of the mishaps.
The weather was frigid when the helicopters lifted off for separate patrols. As a matter of routine when a chopper returns from over-ocean flights, technicians give the engines a hot-water wash to remove potentially corrosive salt spray.
A solution of 60 per cent fresh water and 40 per cent methanol - or anti-freeze - is hosed on the hot engines.
Ashton said investigators have determined that there was no methanol in the mixture. With the air temperature between -11 C and -18 C in both instances, ice quickly formed on the compressors.
Aboard the frigate Charlottetown, flight line crews noticed a blue flame shooting out of the engine, as warning indicators flashed in the cockpit. The pilots immediately killed the engine.
The circumstances were repeated later that evening with a different Sea King aboard the destroyer Athabaskan. In that case, the pilots shut down the engine before flames started flickering out the vents.
The navy has decades of experience launching and recovering aircraft from warships in the icy grip of the North Atlantic.
Ashton says after 10 months, investigators have not been able to determine why the engine wash solution on both ships was not properly set and whether negligence was involved.
No was injured in either incident, but both helicopters were grounded and their engines removed for repairs, which are continuing, she said.
A bill for those repairs has yet to be finalized and Ashton wouldn't speculate on damages. Both helicopters and a third aircraft aboard the supply ship were lifted off the warships by crane once back in port for safety reasons.
"An investigation is still ongoing," Ashton said.
In the meantime, the air force has tightened maintenance regulations, ensuring that methanol is carried aboard ships where helicopters are deployed.
The CH-124 Sea Kings, which have been in service over 40 years, are due to be replaced by new Sikorsky CH-148 Cyclones, starting later this year
OTTAWA - Two of the navy's aging Sea King helicopters suffered debilitating engine fires on the same day aboard different warships under circumstances that flight safety investigators are at loss to explain.
A preliminary investigation suggests the No. 2 engines on both aircraft overheated because they were inexplicably sprayed with fresh water, clogging air compressors with ice.
Why it happened on two ships - dozens of kilometres apart - within hours of each other is the subject a continuing probe.
"I'm baffled with that question myself," Capt. Katherine Ashton, a former Sea King pilot and currently a flight-safety investigator, said Monday.
The mysterious incidents, which took place aboard HMCS Charlottetown and HMCS Athabaskan on March 7 last year, are detailed in documents obtained by The Canadian Press under the Access to Information Act.
Both warships were part of a naval exercise off southern Nova Scotia and were accompanied by the supply ship HMCS Preserver, according to an incident report filed the day of the mishaps.
The weather was frigid when the helicopters lifted off for separate patrols. As a matter of routine when a chopper returns from over-ocean flights, technicians give the engines a hot-water wash to remove potentially corrosive salt spray.
A solution of 60 per cent fresh water and 40 per cent methanol - or anti-freeze - is hosed on the hot engines.
Ashton said investigators have determined that there was no methanol in the mixture. With the air temperature between -11 C and -18 C in both instances, ice quickly formed on the compressors.
Aboard the frigate Charlottetown, flight line crews noticed a blue flame shooting out of the engine, as warning indicators flashed in the cockpit. The pilots immediately killed the engine.
The circumstances were repeated later that evening with a different Sea King aboard the destroyer Athabaskan. In that case, the pilots shut down the engine before flames started flickering out the vents.
The navy has decades of experience launching and recovering aircraft from warships in the icy grip of the North Atlantic.
Ashton says after 10 months, investigators have not been able to determine why the engine wash solution on both ships was not properly set and whether negligence was involved.
No was injured in either incident, but both helicopters were grounded and their engines removed for repairs, which are continuing, she said.
A bill for those repairs has yet to be finalized and Ashton wouldn't speculate on damages. Both helicopters and a third aircraft aboard the supply ship were lifted off the warships by crane once back in port for safety reasons.
"An investigation is still ongoing," Ashton said.
In the meantime, the air force has tightened maintenance regulations, ensuring that methanol is carried aboard ships where helicopters are deployed.
The CH-124 Sea Kings, which have been in service over 40 years, are due to be replaced by new Sikorsky CH-148 Cyclones, starting later this year
