Summary
The FAA proposes to adopt a new airworthiness directive (AD) for certain Boeing transport category airplanes. This proposed AD would require determining if the terminal fittings of the spars of the wings are made of 7079 aluminum alloy material. For any positive finding, the proposed AD would require doing repetitive inspections for cracks and corrosion of all exposed surfaces of the terminal fitting bores; doing repetitive inspections for cracks, corrosion, and other surface defects, of all exposed surfaces, including the flanges, of the terminal fitting; applying corrosion inhibiting compound to the terminal fittings; and repairing or replacing any cracked, corroded, or defective part with a new part. This proposed AD also provides for an optional terminating action for the repetitive inspections. This proposed AD results from reports of cracking of the terminal fittings of the spars of the wings. We are proposing this AD to detect and correct stress-corrosion cracking of the terminal fittings, which could result in the failure of one of the terminal fitting connections. Such a failure, combined with a similar failure of one of the other three terminal fittings, could result in the inability of the airplane structure to carry fail-safe loads, which could result in loss of structural integrity of the wing attachment points.