A faulty rotor spindle suspected to be the cause of a fatal helicopter crash west of Edmonton last week has grounded some Bell helicopter models across North America.
The main rotor hub strap pins on certain Bell 212, 204B and 205 helicopters need to be inspected and replaced, Transport Canada said. in an emergency airworthiness directive published on Monday.
The advisory warns that the pins may fail, causing the head and rotor blade to separate from the aircraft in mid-flight.
“Failure of a main rotor hub strap pin will cause the main rotor blade to detach and loss of control of the helicopter,” the directive said.
The serial numbers on the rotor hub strap pins of the affected Bell helicopters must be checked against an airworthiness directive list before they can fly again, Transport Canada said.
“During an investigation into a recent fatal Bell 212 helicopter crash in Canada, it was discovered that one of the outboard main rotor hub strap pins was found to be[s] … Sheared during flight, causing the main rotor blade and main rotor head to detach. “
A spokesperson for the Transportation Safety Board of Canada told CBC News that the Transport Canada advisory was triggered by the TSB’s investigation into the fatal crash of a Bell 212 on June 28 near Evansburg, Alberta.
Pilot Heath Coleman, 48, of Prince George, British Columbia, died while battling a wildfire.
Coleman was alone when the helicopter he was piloting crashed in a rural area near the fire front.
The defective part had only accumulated 20 hours of service, according to Transport Canada’s advice. He stated that an inspection of another Canadian Bell 212 revealed that a main rotor hub strap pin was “bent” after approximately 29 hours of service.
The cause of the part’s failure has not been determined, Transport Canada said.
Bell Helicopters issued a “notice of withdrawal from service” on the defective parts Monday evening.
The company said some of the main rotor hub strap pins “may not have been manufactured in accordance with engineering design requirements.”
Bell requires that records be checked before the next flight and that any defective parts be replaced. The company said work on each plane could take 20 hours.
A spokesperson for Bell said company officials could not discuss the details due to the ongoing crash investigation, but offered their condolences to the Coleman family.
If you lose the rotor blades, it is equivalent to an airplane losing its wings.-Jon Lee, BST
Jon Lee, TSB regional operations director for Western Canada, said there were clear signs at the crash site that the rotor axis had failed.
The rotor blades were not with the helicopter wreckage.
“For us as investigators this is a very obvious first signal that something has happened in flight rather than as a result of a ground impact,” Lee said in an interview on Tuesday.
A blade was found 23 meters from the crash site. The other was found on the second day of the investigation, 46 meters from the site.
“When we were able to retrieve the rotor blades, we could see that this retaining pin had sheared,” Lee said.
The parts are currently being examined at the TSB laboratory.
“Gravity takes over”
Lee said the crash was not survivable.
“Basically, with a helicopter, if you lose the rotor blades, it’s equivalent to an airplane losing its wings,” Lee said.
“You’ve lost all ability to maintain lift and gravity takes over.”
The 175-hectare forest fire near Evansburg has been burning since June 22 when it triggered a temporary evacuation of neighboring homes. It is now classified under control.
“Something catastrophic has happened”
Coleman was a longtime employee of Yellowhead Helicopters.
Company CEO Jacob Forman said Coleman was flying to retrieve firefighters from a swamp near the blaze.
Forman, who attended the scene, told CBC News his team helped locate the missing second blade.
“It seemed like the essential piece of evidence that was going to be needed,” he said.
Forman said he never thought the pilot’s error could be to blame. Coleman has been a talented and deeply trusted member of his team for nearly a decade.
“Something catastrophic happened… he was unlucky.”