Tool Bag Takes Out Tail Rotor: Fatal AS350B2 Accident, Tweed, ON
Four died when a tool bag came loose and struck the tail rotor of a helicopter carrying workers of an electricity utility company. The accident involved Airbus Helicopters AS350B2 C-GOHS operated by Ontario’s Hydro One Networks need Tweed, ON on 14 December 2017.
The Transportation Safety Board of Canada (TSB) say in an initial report on 21 December 2017 that a single pilot and three Hydro One linesmen were on board, supporting maintenance on high-power electricity transmission lines:
As part of the work being conducted, a few bags used for carrying tools and supplies were carried externally on a platform extending out of the right side of the fuselage. These bags, when carried externally, are normally attached with double-lock carabiners.
Shortly before the accident, the pilot picked up the 3 linemen at the base of a tower and was transporting them to a nearby staging area. While nearing the staging area, one of the bags that was being carried externally blew off the platform and, along with its attached carabiner, struck the tail rotor.
Shortly thereafter, while the pilot was attempting to land, the helicopter departed from controlled flight, all 3 passengers became separated from the helicopter while it was still airborne. The helicopter subsequently crashed nearby.
We have found a heavily damaged white canvas bag, with a damaged carabiner attached, and the tip of a tail rotor blade over 600 meters away from the crash site.
Two of the three linesmen were not wearing seat belts.
TSB have issued a safety advisory:
Cargo must be adequately secured at all times, to prevent it from shifting or departing the helicopter during flight.
Passengers who do not wear seat belts risk serious injury or death in the event of an emergency.
We will follow developments in this accident as the TSB report on their ongoing investigation.
Previous Aerossurance articles include:
- Bell 429 TR Pitch Change Link Bearing Failure: Bell Helicopter issues an Alert SB but it takes 6 months for an ‘Emergency’ AD and compliance by the operator.
- Fatal H500 /369D Low Altitude Hover Power Loss: Power Line Maintenance Project: An engine compressor failure while installing power line markers resulted in an unsurvivable impact and fire.
- Ignoring Corrosive Environment Brings Down B206 Helicopter: The Aviation Safety Council of Taiwan identify a surprising lack of aero engine maintenance knowledge and a series of non-compliances in an aircraft spray washing powerlines.
- The Tender Trap: procuring aviation services
The commercial pilot reported that, after completing an external cargo lift operation, he landed at a remote location to jettison the lift cable and to board the two ground workers for a ferry flight back to their home base.
Shortly after liftoff, the pilot felt a moderate aberration in the cyclic flight control, followed by a significant vertical vibration. The pilot subsequently observed that the main rotor (MR) blade track had a substantial blade spread. Subsequently, the pilot conducted a forced emergency landing…
…examination of the helicopter revealed that one MR blade was missing about 9 inches of its blade tip, consistent with impact with an object of substantial mass…
The pilot reported that he released the lift cable before the flight…[and]…the ground crew placed the coiled cable in the rear compartment that had no doors.
…based on the damage to the MR blades, it is likely that the cable exited the helicopter during liftoff and subsequently impacted the MR, which resulted in the separation of an MR blade tip and the vertical vibration of the helicopter.
This accident, while fortuitously non-fatal, pre-dated the Ontario accident by over a year.