Summary
We propose to adopt a new airworthiness directive (AD) for certain Model L-1011 series airplanes. This proposed AD would require repetitive inspections for cracking of the wing rear spar and upper surface zones, and repair if necessary. This proposed AD results from a damage tolerance analysis conducted by the manufacturer indicating that fatigue cracking could occur in those areas. We are proposing this AD to detect and correct such fatigue cracking, which could result in cracking that grows large enough to reduce the wing strength below certificated requirements and possibly cause fracture of the rear spar, resulting in extensive damage to the wing and possible fuel leaks.