COPENHAGEN, Denmark (AP) — Norwegian authorities say the manufacturer of the helicopter that crashed last month in Arctic Norway killing six people is calling for "immediate visual inspection" of recently delivered choppers of the same type following preliminary findings.

Norway's Accident Investigation Board says "the connection between the engine and the main gearbox has led" Airbus Helicopters to issue an alert as "a precautionary measure."

The Airbus AS350 helicopter, which was transporting youth to and from a nearby music festival, crashed southwest of Alta on Aug. 31.

The agency said Wednesday the helicopter that crashed in Norway had "less than 73 flight hours," adding that it "has, at this stage, not concluded whether, or not, failure of the connection between the engine and the main gearbox is a causal factor."