Summary
This document proposes the supersedure of an existing airworthiness directive (AD), applicable to certain McDonnell Douglas Model MD-90-30 airplanes, that currently requires repetitive fluorescent penetrant and magnetic particle inspections to detect fatigue cracking of the main landing gear (MLG) piston, and repair if necessary. This action would expand the applicability of the existing AD to require the currently required inspections, and corrective actions if necessary, on additional airplanes and MLG piston part numbers, and would require repetitive inspections for evidence of cracking in the paint topcoat of the MLG pistons. This action also would require replacement of certain MLG shock strut piston assemblies with new or serviceable improved assemblies, which would terminate the requirements of this AD. These actions are necessary to prevent fatigue cracking of MLG pistons, which could result in failure of the pistons, and consequent damage to the airplane structure andinjury to flightcrew, passengers, or ground personnel. These actions are intended to address the identified unsafe condition.