ASN Wikibase Occurrence # 202964
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| Date: | Thursday 14 December 2017 |
| Time: | 11:46 |
| Type: |  Eurocopter AS 350B2 Ecureuil |
| Owner/operator: | Hydro One Networks |
| Registration: | C-GOHS |
| MSN: | 3240 |
| Year of manufacture: | 1999 |
| Engine model: | Turbomeca ARRIEL 1D1 |
| Fatalities: | Fatalities: 4 / Occupants: 4 |
| Aircraft damage: | Destroyed |
| Category: | Accident |
| Location: | Tweed, ON -
 Canada
|
| Phase: | Approach |
| Nature: | External load operation |
| Departure airport: | |
| Investigating agency: | TSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
A Hydro One Networks Inc. AS 350B2 helicopter equipped with an external platform, was transporting crews of power line technicians between a staging area and transmission towers in an area located 8 nautical miles north-northeast of Tweed, Ontario.
At 1144 Eastern Standard Time, the pilot picked up a crew of 3 power line technicians near the bottom of a tower for a return flight to the staging area. It had become common practice for power line technicians to attach tool bags and other small items to the external platform for flights to and from work sites. In line with this practice, the technicians attached a few items to the platform while boarding the helicopter, and then took their seats in the aft cabin.
The practice of carrying external loads attached to the platform was not a formalized procedure at the company and, as a result, adequate controls were not in place to ensure that these objects were properly stored or secured. Consequently, an empty canvas supply bag with an attached carabiner that was being carried on the platform was not adequately secured before the helicopter departed for the return flight to the staging area.
When the helicopter was 0.26 nautical miles from the staging area, the canvas bag separated from the platform and struck the helicopter's tail rotor, causing significant damage, severe imbalance, and intense vibration.
Shortly after, while the pilot was attempting to land, the helicopter's tail rotor, tail rotor gearbox, and vertical fin separated from the helicopter. The helicopter became uncontrollable and collided with terrain. The 3 power line technicians were unrestrained and became separated from the helicopter, either slightly before or during the impact, and received fatal injuries from contact with the helicopter or the surrounding terrain. The pilot was fatally injured on impact. The helicopter was destroyed.
TSB Findings as to causes and contributing factors:
1. When the Air Stair was being used for aerial transfers, it was company practice to attach small external loads temporarily to the Air Stair during aerial transfer of personnel and equipment, while the helicopter hovered at the top of transmission towers.
2. There was no formal guidance prohibiting the carriage of small external loads during flights that did not involve the Air Stair. As a result, it became common practice for power line technicians to attach tool bags and other small external loads to the Air Stair for flights to and from work sites.
3. Because this practice was not formalized, adequate controls (e.g. standardized procedures, training, checklists, or peer checks) were not in place to ensure that objects were properly stored in or secured to the helicopter. In this occurrence, part of the external load was not adequately secured.
4. The pilot was likely unable to confirm that the load was stored inside the cabin because he was occupied with controlling the helicopter during the light-on-skids pickup and would have been unable to turn his head to see the entire Air Stair.
5. The power line technicians may not have attached their safety belts after boarding the helicopter because they perceived the risk on the short flight to be low, or because they had difficulty attaching the belts over their cold-weather gear.
6. A preform bag and its attached carabiner that had been on the Air Stair struck the helicopter's tail rotor, causing significant damage, severe imbalance, and intense vibration.
7. As the pilot attempted to land the damaged helicopter near the staging area, the tail rotor assembly failed entirely and the helicopter entered an uncontrolled rotation. Shortly thereafter, the helicopter struck terrain and was destroyed.
8. The power line technicians were unsecured and became separated from the helicopter either slightly before or during the impact, and received fatal injuries from contact with the helicopter or the surrounding terrain.
Accident investigation:
 |
|
Sources:
http://www.cbc.ca/news/canada/ottawa/helicopter-crash-tweed-fatalities-1.4448706
http://wwwapps.tc.gc.ca/saf-sec-sur/2/ccarcs-riacc/ADet.aspx?id=19450&rfr=RchSimp.aspx
https://www.flickr.com/photos/news46/3540566651
http://www.bst-tsb.gc.ca/eng/enquetes-investigations/aviation/2017/a17o0264/a17o0264.asp
https://www.nationalnewswatch.com/2017/12/16/hydro-one-releases-names-of-four-employees-killed-in-eastern-ontario-helicopter-crash/#.WjVpUtLia9I
http://aerossurance.com/helicopters/toolbag-rotor-as350-hydroone/
http://www.tsb.gc.ca/eng/enquetes-investigations/aviation/2017/a17o0264/a17o0264.asp#
Location
Images:
Photo: TSB
Media:
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 14-Dec-2017 18:59 | Anon. | Added |
| 14-Dec-2017 19:00 | harro | Updated [Cn, Operator, Other fatalities, Embed code, Narrative] |
| 14-Dec-2017 19:30 | Iceman 29 | Updated [Embed code, Photo, ] |
| 14-Dec-2017 19:40 | Aerossurance | Updated [Time, Aircraft type, Location, Damage, Narrative] |
| 14-Dec-2017 21:05 | Geno | Updated [Source] |
| 15-Dec-2017 10:49 | Iceman 29 | Updated [Embed code] |
| 16-Dec-2017 09:38 | Anon. | Updated [Phase, Source, Narrative] |
| 16-Dec-2017 18:44 | Iceman 29 | Updated [Source] |
| 18-Dec-2017 20:06 | Iceman 29 | Updated [Embed code] |
| 21-Dec-2017 20:43 | Aerossurance | Updated [Aircraft type, Nature, Source, Embed code, Narrative] |
| 22-Dec-2017 08:52 | Aerossurance | Updated [Source] |
| 01-Nov-2019 09:15 | harro | Updated [Time, Embed code, Narrative, Photo, Accident report, ] |
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