The Nov. 10 crash took the lives of both pilots and three passengers. Two people survived.
The TSB said the Fairchild SA227 Metro III, a twin-engine turboprop, departed Sioux Lookout normally and had been in communication with the appropriate air traffic officials en route to Red Lake, about 500 km northwest of Thunder Bay.
The crew declared an emergency on its final approach. The plane struck trees and power lines on its way down and crashed at around 6:30 p.m. CST just south of the Red Lake Airport near Hwy 125.
The investigation discovered power loss in the left engine was "near total," and the crew had only 56 seconds between the time it malfunctioned and the time the aircraft struck the trees.
"The crew was unable to identify the nature of the engine malfunction, preventing them from taking timely action to control the aircraft," the report says.
Recovery was impossible
The crew lost control at an altitude where recovery wasn't possible, the TSB says.
The board says the plane's landing gear generated higher drag, which contributed to the aircraft losing speed.
The report says Bearskin Airlines, engine manufacturer Honeywell and Transport Canada have each taken steps to help prevent similar crashes from happening.
The board says the airline has since revised its procedures to ensure that the propeller on a malfunctioning engine does not cause excessive drag.
Honeywell, the engine manufacturer, has increased the inspection frequency on fuel nozzles and clarified inspection procedures.
Ontario Provincial Police identified the two pilots killed in the crash as Aniruddh Sawant, 25, of Mississauga, Ont., and Peter Traczuk, 34, of Winnipeg.
The three passengers who died — Anna Johannesson, 53, Peter Struk, 53, and 64-year-old Sharron Taylor — were all from Red Lake.