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
We have previously written:
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.
UPDATE 14 November 2018: The NZCAA has issued a safety alert on loose article. This is reported by the press to be after a specific fatal accident (Hughes 369D ZK-HOJ 18 Oct 2018) were witnesses reported seeing clothing fall from the helicopter and become wrapped around the tail rotor. The alert points to a Robinson Helicopter safety video:
There is evidence that a pair of over-trousers that had been packed in the cabin came out of the helicopter and became entangled in the tail rotor. Paint marks on the over-trousers matched the colour and profile of the tail rotor blades, and marks on a tail rotor blade match a zip and dome connector on the over-trousers. …evidence also revealed three incidents in the month prior to the accident in which doors on this helicopter opened in flight. Effective safety management depends on such incidents being reported and investigated, but none of these occurrences was recorded in the operator’s incident reporting system.
UPDATE 10 June 2019: Troublesome Tiedowns: The Sequel A Robinson R22 suddenly fails to respond to control inputs and descends and impacts the sea. Investigators find a tie-down wrapped around the main rotor head.