Abstract: At 7:15 a.m. on December 1, 2004, Employee #1, an aircraft mechanic for an aircraft manufacturing company, and coworkers were installing a FOD curtain on the inside of the fuselage of an aircraft under construction. During this procedure, the employees were standing on a rolling scaffold, which had been rolled onto the cargo deck of the plane. After the scaffold was rolled into the plane, doors that were hinged to the perimeter of the scaffold were lowered down to provide a working surface that extended to the inside surface of the fuselage. However, a bracket that extended from the edge of the fuselage prevented one of the doors to be completely lowered into place. This left an opening in the working surface. As the employees were installing the FOD curtain, moving sideways along the scaffolding, Employee #1 lost track of the placement of his feet and fell through the opening in the work surface. Employee #1 was hospitalized and treated for fractured ribs and soreness in his shoulders and arms.