Summary
The FAA proposes to adopt a new airworthiness directive (AD) for certain McDonnell Douglas airplanes, identified above. This proposed AD would require a one-time inspection to determine the configuration of the airplane (tee or angle doubler installed on the left and right side of the flat aft pressure bulkhead from Longeron 9 to Longeron 13). This proposed AD would also require repetitive inspections for cracking of the tee or angle doubler, and corrective actions if necessary. This proposed AD results from a report indicating that numerous operators have found cracks on the tee. We are proposing this AD to detect and correct stress corrosion cracking of the tee or angle doubler installed on the flat aft pressure bulkhead. Cracking in this area could continue to progress and damage the adjacent structure, which could result in loss of structural integrity of the airplane.