Summary
We propose to adopt a new airworthiness directive (AD) for certain Boeing Model 707 airplanes, and Model 720 and 720B series airplanes. This proposed AD would require repetitive detailed inspections to detect cracks and corrosion on any existing repairs and at certain body stations of the visible surfaces of the wing to body terminal fittings including the web, flanges, and ribs; and applicable related investigative and corrective actions. This proposed AD results from reports of cracks found in the wing to body terminal fittings during routine inspections. We are proposing this AD to prevent cracks and corrosion in the body terminal fittings, which could cause loss of support for the wing and could adversely affect the structural integrity of the airplane.