CARRABASSETT VALLEY — A preliminary investigation has determined that a fractured drive shaft in the gearbox on the King Pine chairlift was the initial cause of an accident that injured seven people at the Sugarloaf ski resort last Saturday.

In a statement released Wednesday, the resort said that a review by resort personnel, engineers from parent company Boyne Resorts and a lift operator licensed by the state determined that a fracture on the main drive shaft of the lift’s secondary gearbox initiated a rollback on the chairlift, the report concluded. The report also said that a manufacturer’s design defect also contributed to the accident by failing to stop the chairlift from rolling backwards, resulting in the injuries.

Engineers have identified a retrofit for the system that they said would solve the problem, the report said.

A drive shaft in one of the two gear boxes that transfer power from the lift’s motor to its bullwheel fractured about 11:30 a.m., according to the report.

The gearbox fracture resulted in the loss of both the primary service brake and an anti-reverse brake, but the main emergency brake, referred to in the report as the “bullwheel brake,” activated properly.

However, the bullwheel brake does not kick in instantly, because the shock of the brake being applied could create “sudden and dramatic movement” along the lift’s haul rope, which could cause people to fall off the lift or even cause a separation of the cable from the lift’s guide wheels.

When the driveshaft failed, the lift traveled backward a total of nine chair lengths — about 460 feet — between the time when the bullwheel brake was activated and when the lift actually stopped, the report notes.

A final safety system intended to prevent the lift from rolling backward, called a “drop dog,” was found to have a flawed switch, investigators found.

The switch is intended to activate a drop dog, a device designed to suspend over the lift’s main operating wheel. However, the engineers said, an inappropriate switch was connected to the safety circuit.

“The investigation indicates that, had an appropriate switch been included in the system, the drop dog would have deployed and the rollback would have stopped immediately.”

Resort officials have contacted the lift’s parts manufacturer to share their findings. Other lifts at Sugarloaf that were found to have the same defect were fixed on Wednesday, with the exception of one lift that remains closed, Sugarloaf spokesman Ethan Austin said. The repairs didn’t affect the U.S. Alpine Championships now being held at the resort.


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