A half-ton air conditioning duct collapsed onto cafeteria tables at an charter school in New Orleans this week. The duct, which stretches across the length of the cafeteria, fell from the ceiling about 6 p.m. Monday, damaging an entire row of cafeteria tables. No children were present at the school and no one was injured. It appears that the duct, weighing between 800 and 1,000 pounds, was incorrectly secured to the ceiling with drywall screws, and did not have adequate support. The installation may have taken place five years ago when the building was managed by the Orleans Parish School Board.