Summary
We propose to adopt a new airworthiness directive (AD) for all McDonnell Douglas Model MD-90-30 airplanes. This proposed AD would require repetitive inspections for cracks of the upper aft skin panels on the horizontal stabilizer, and related investigative and corrective actions if necessary. This proposed AD results from a report of cracks found in the aft skin panels on the upper right side of the horizontal stabilizer at the aft inboard corner. We are proposing this AD to detect and correct cracks in the fail-safe structure that may not be able to sustain limit load, which could result in the loss of overall structural integrity of the horizontal stabilizer.