Safety officials determine cause of Hydro One chopper crash near Tweed, Ont.

Thu, Dec 21: Though their investigation is still considered preliminary, the Transportation Safety Board says a cloth tool bag was blown off a platform attached to the side of the chopper during mid-air power line maintenance work and hit the helicopter’s tail rotor. Mark Carcasole reports.

• Tool bag may have caused Ontario helicopter crash that killed 4: Transportation Safety Board