The investigation into the fatal crash of a Yellowhead Helicopters Bell 212 last week has implicated a defective main rotor hub strap pin, according to an emergency airworthiness directive (AD) from Transport Canada.
Pilot Heath Coleman of Prince George, British Columbia was killed on June 28 when his helicopter went down during firefighting operations near Edmonton, Alberta. He was the only person on board.
According to the AD effective July 5, investigators discovered that one of the outboard main rotor hub strap pins sheared off during flight, leading to detachment of the main rotor blade and rotor head. The failed pin had reportedly accumulated just 20 hours in service.
Inspection of another Canadian Bell 212 helicopter found a main rotor hub strap pin made by the same manufacturer, with the same serial number prefix “FNFS,” to be deformed after less than 30 hours in service.
Although defective main rotor hub strap pins were only reported on Bell 212 helicopters, strap pins of the same part number can also be installed on Bell 204B, 205A-1 and 205B helicopters. As a precautionary measure, the AD — following an alert service bulletin (ASB) from Bell — mandates that operators of these models determine the serial numbers of installed strap pins, and replace any with the prefix “FNFS” before further flight.
“While we’re not at liberty to discuss details of the Transport Safety Board investigation, all of us at Bell are extremely saddened by this loss,” a Bell spokesperson told Vertical by email. “Our heartfelt thoughts go out to those onboard the aircraft as well as their family and loved ones. Even though the investigation is still in progress, to insure fleet safety, the main rotor strap pins identified in the ASBs should be removed from service before the next flight.”
Transport Canada was the first regulator to issue an emergency AD on the subject. Even in advance of the AD, however, the U.S. Department of Agriculture Forest Service on July 4 initiated a temporary stand down of its Bell 205, 210, and 212 helicopters as a safety precaution. The Forest Service relies on a number of these aircraft for firefighting activities, including the transport of personnel.
“The USDA Forest Service then implemented the actions outlined in the Bell Helicopter alert service bulletin (issued July 5) for all affected helicopters. Most of these contract aircraft have already returned to service and we expect to have all of the inspections completed soon,” a Forest Service spokesperson told Vertical on July 6.
Update: On July 8, a Forest Service spokesperson told Vertical that the stand down impacted a total of 40 helicopters (34 on exclusive use contracts and six on call-when-needed contracts). “All of the affected helicopters were then inspected and returned to service with minimal impact to our wildland fire operations. Safety is the highest priority in all USDA Forest Service aviation operations,” the spokesperson said.
The Federal Aviation Administration has also now issued its own emergency AD.
