MEDIA ADVISORY: Sugarloaf Releases Preliminary Findings on King Pine Lift Rollback
Carrabassett Valley, ME (March 22, 2015) - One day after a rollback incident on the King Pine lift at Sugarloaf, investigators from Sugarloaf worked in conjunction with an engineer from the State of Maine Board of Elevators and Tramways to investigate the cause of the accident that resulted in injuries to seven guests.
The investigation began yesterday, shortly after the evacuation of the lift was complete. Though it is ongoing, the investigation's preliminary findings revealed that the trigger for the incident was a major mechanical failure in one of two gearboxes connecting the lift's electric motor to its drive bullwheel. A bullwheel is a large, metal wheel, around which the lift cable - which supports the chairs - is tensioned.
Just one day before the incident, the gearbox passed a sophisticated routine preventive maintenance procedure intended to identify potential problems.
The gearbox failure effectively de-coupled the bullwheel from the lift's primary service brake, which is located on the drive shaft between the two gearboxes, and its anti-reverse brake, which is the first of three redundant backup mechanisms for preventing reverse travel.
At this point, the emergency bullwheel brake, which uses calipers to apply braking pressure to the flange of the bullwheel itself, was applied by the lift attendant. This brake slowed the speed of the rollback and ultimately brought the lift to a stop. The application of the emergency brake by the lift attendant likely prevented a more extensive rollback.
The final braking mechanism, known as a drop dog (a large metal pin that drops into the bullwheel to prevent rotation), apparently failed to deploy as designed.
"The cause of the gearbox failure and the failure of the drop dog to deploy as designed both remain under investigation," Ethan Austin, Sugarloaf's Director of Marketing said. "It is likely that determining the root cause of these failures will require extensive analysis."
Lift mechanics routinely check gearbox oil levels as part of their daily pre-operating checklist. But much like an automobile transmission, the machinery inside of a lift gearbox is not easily observed, so Sugarloaf contracts for routine maintenance tests that can indicate potential problems before they occur.
The tests include oil analysis, which can reveal microscopic particles of metal that indicate undue wear inside the machinery, and vibration analysis, which can reveal gears out of balance and incipient failure.
An oil analysis was conducted on the King Pine lift on January 19, and a vibration analysis was conducted on March 20 - one day before the incident. Both tests were conducted by outside contractors who specialize in gearbox analysis, and neither revealed any irregularities.
The gearbox last underwent major servicing, including the replacement of worn components, just before the start of the 2011-2012 winter season. The work was performed by a contractor who specializes in gearbox maintenance.
"Our first concern remains with those who were injured, and those who went through a truly frightening experience," Austin said. "Based on what we know now, we're grateful that this situation wasn't any worse. It's too soon to say what, if any, changes to operational protocols will be made, and part of that determination will hinge upon what's revealed by the next stages of the investigation."
Austin said the lift will remain closed pending further investigation.
For previous statements release by Sugarloaf regarding this incident, please visit www.sugarloaf.com/media-room.
Director of Marketing