A chairlift malfunction that injured seven skiers at the Sugarloaf ski area and resort was caused by a broken drive shaft on a mechanical gearbox that took the main braking system offline, and another key braking system failed to work because of a design flaw, investigators said Wednesday.
But the King Pine Quad lift, carrying more than 200 skiers, was brought to a stop by an emergency brake system that activated automatically, contrary to early reports that a worker had to manually activate the brakes.
A team of engineers and a state inspector released the findings of a preliminary review and investigation at the ski resort in Carrabassett Valley. They said they were correcting the design flaw that was identified.
Sugarloaf's general manager said he was grateful to have "a clearer understanding of what occurred."
"Our first thoughts remain with those injured, and our sincere hope for their speedy recovery," general manager John Diller said in a statement.
The Saturday mishap came just days before top skiers began arriving for the national alpine championships, which started Wednesday.
The day before the mechanical failure, workers had checked all lifts at the resort for excessive vibration and found no evidence pointing to any imminent problem with the King Pine lift.
Officials said the fractured drive shaft caused the secondary gearbox to decouple from the main gearbox, knocking the main brakes out of commission and necessitating the emergency brake.
Another brake system, called a drop dog, akin to putting a stick in the spokes of a spinning bicycle wheel, failed to activate because of an electronic switch that was the wrong type for the application, officials said Wednesday.
Sugarloaf was replacing the switch on all similar chairlifts. Sugarloaf and its parent company, Boyne Resorts, have been in touch with the chairlift's parts manufacturer to share the findings, officials said.