Laminated plastic wings being built by Boeing Co. as replacements for metal wings on the Navy's A-6 carrier-based bomber tend to peel apart, and the company has had problems in attaching the wing to the aircraft, the publication Defense Week reported. As a result, the Navy's schedule for getting the planes back in the air has been delayed, it said. Some have been grounded for two years. The company insisted it was solving the problems. The original wings suffered metal fatigue, and Boeing won a potential $1.2-billion contract to replace them, guaranteeing that its graphite epoxy wings would last almost four times as long as metal wings.