Summary
We propose to adopt a new airworthiness directive (AD) for all Model MD-90-30 airplanes. This proposed AD would require repetitive inspections for cracking of the left and right upper center skin panels of the horizontal stabilizer, and corrective action if necessary. This proposed AD was prompted by a report of a crack found in the upper skin panel at the aft inboard corner of a right horizontal stabilizer. We are proposing this AD to detect and correct cracks in the horizontal stabilizer upper center skin panel. Uncorrected cracks might ultimately lead to the loss of overall structural integrity of the horizontal stabilizer.