PORTLAND, Maine (AP) - U.S. ski resorts are being warned to check more than 100 chairlifts after engineers identified a design flaw believed to have contributed to an accident that injured seven people at Sugarloaf in Maine.

PORTLAND, Maine (AP) U.S. ski resorts are being warned to check more than 100 chairlifts after engineers identified a design flaw believed to have contributed to an accident that injured seven people at Sugarloaf in Maine.

Partek Ski Lifts, based in Pine Island, New York, issued a bulletin Thursday warning operators using Borvig and Partek lifts to check safety components and to pay attention to a particular electrical switch.

Engineers believe the wrong switch was used on a lift, preventing a safety system from locking a 27-year-old Borvig chairlift in place after a mechanical failure last weekend. Seven skiers were hurt.

The National Ski Areas Association believes about 170 lifts could be affected by the design issue. There are about 3,500 lifts in the U.S.