Brake Drum Wheel Cylinder problems of the 1998 Mercury Grand Marquis

Consumer stated while driving a chatter noise could be heard, upon inspection of the vehicle, consumer noticed that the right rear brake caliper piston was almost fully out of its cylinder and jammed slightly in a cocked position, the inner brake pad lining was completely worn away with its metal mount grinding away into the brake disc, consumer took the vehicle to the dealer and had the 2 rear disc and right rear caliper replaced, consumer believes there is a serious design flaw with the abs-trac control brake system that would cause such a failure.