Summary
We propose to supersede an existing airworthiness directive (AD) that applies to all Lockheed Martin Corporation/Lockheed Martin Aeronautics Company Model L-1011 series airplanes. The existing AD currently requires repetitive inspections to detect corrosion or fatigue cracking of certain structural elements of the airplane; corrective actions if necessary; and incorporation of certain structural modifications. Since we issued that AD, we have received reports of small cracks in additional areas outside those addressed in the existing AD, prior to the inspection threshold required by the existing AD. This proposed AD would reduce certain compliance times for the initial inspection, and the repetitive inspection interval for certain airplanes. We are proposing this AD to prevent corrosion or fatigue cracking of certain structural elements, which could result in reduced structural integrity of the airplane.