HALIFAX -- A report into an emergency landing by a Sea King helicopter says leaks beneath a dime-sized seal on a hydraulic system caused the aircraft to set down in a parking lot in suburban Halifax last year.
The report by safety officers says the emergency landing last November was the fifth time since 2000 that an O-ring -- a rubber washer -- or packing material beneath it have broken down and started to leak highly pressurized hydraulic fluids. The fluid systems are similar to the power steering in a car, providing the pressure to pistons that control the angle of the aircraft's blades.
The report prepared last fall says three other incidents were noted during maintenance checks and one other was noticed during a flight in 2011, resulting in a landing.
In the case in November, the incident report obtained under freedom of information legislation says air crew noticed red fluid dripping from the ceiling and a warning light went off. The helicopter landed in a gravel lot near a Sobeys grocery store in the Halifax suburb of Bedford in mid-afternoon.
The five-person crew wasn't hurt but workers in a nearby pharmacy and dental office said at the time they were unnerved by the noisy appearance of the helicopter.
The O-rings go over the threaded end of a five-centimetre metal elbow that feeds hydraulic fluid into the system that moves the rotor blades.
The report written by safety officers from Canadian Forces Base Shearwater says "there was a slight flattening/deformation of the packing observed under one side of the O-ring."
It says "a slight deformation of the packing and the resulting small leak over an extended time period is the most probable cause of the primary hydraulic system failure."
Maj. Mark Shelden, a flight safety officer, said the aircraft has a backup system for hydraulic fluids flowing to the rotor, so the pilots faced no risk of a crash as they landed the aircraft.
"Imagine your car with two power steering systems in it. If one of them failed, the other one will still do the job," he said in an interview.
Attempts by the federal government to replace the military's aging Sea Kings have been repeatedly delayed. The military is still waiting for new helicopters from Sikorsky Aircraft Corp., which was selected nine years ago to supply 28 helicopters.
A $5.9-billion contract to acquire the CH-148 Cyclones was signed by the government in 2004, a milestone event in a two-decade search to find a replacement for the CH-124 Sea Kings after former prime minister Jean Chretien cancelled a deal to replace the choppers in 1993.
Shelden said the O-ring failure last November and the leak of about 1.5 litres of hydraulic fluid aren't a serious concern.
"Considering the number of hours we put on these aircraft every year, four (incidents) since 2000 is pretty good," he said, adding that each of the Sea Kings flies about 300 hours a year.
He said the aircraft's maintenance team properly fitted the O-ring, and safety officers concluded that existing inspections and procedures are adequate.
"I really have no concerns about this at all. It's an airworthy aircraft," he said.
"The Sea King has a proud record. It has an enviable record. Considering what we've asked it to do for 50 years, I think she's performed very well."
