ASN logo
ASN Wikibase Occurrence # 202964
Last updated: 14 September 2021
This information is added by users of ASN. Neither ASN nor the Flight Safety Foundation are responsible for the completeness or correctness of this information. If you feel this information is incomplete or incorrect, you can submit corrected information.

Date:14-DEC-2017
Time:11:46
Type:Silhouette image of generic AS50 model; specific model in this crash may look slightly different
Eurocopter AS 350B2 Ecureuil
Owner/operator:Hydro One Networks
Registration: C-GOHS
MSN: 3240
Fatalities:Fatalities: 4 / Occupants: 4
Other fatalities:0
Aircraft damage: Written off (damaged beyond repair)
Category:Accident
Location:Tweed, ON -   Canada
Phase: Approach
Nature:External load operation
Departure airport:
Destination airport:
Investigating agency: TSB Canada
Narrative:
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.

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#

Accident investigation:
cover
  
Investigating agency: TSB Canada
Status: Investigation completed
Duration: 1 year and 10 months
Download report: Final report

Media:


Images:



Photo: TSB

Revision history:

Date/timeContributorUpdates
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, ]

Corrections or additions? ... Edit this accident description