Summary
This document proposes the supersedure of an existing airworthiness directive (AD), applicable to certain McDonnell Douglas Model DC-9-80 series airplanes and Model MD-88 airplanes, that currently requires a one-time inspection to detect cracking of the main landing gear (MLG) pistons, and repair or replacement of the pistons with new or serviceable parts, if necessary. This action would require, among other actions, repetitive dye penetrant and magnetic particle inspections to detect cracks of the MLG pistons; repair and replacement of discrepant parts; and installation of a preventative modification; as applicable. This action also would provide for an optional terminating action for certain MLG pistons. This proposal is prompted by additional reports of failure of the MLG pistons during towing of the airplanes. The actions specified by the proposed AD are intended to prevent fatigue cracking of the MLG pistons, which could result in failure of the pistons and subsequent damage to the airplane structure or injury to airplane occupants.