Summary
This document proposes to revise an existing airworthiness directive (AD), applicable to all McDonnell Douglas Model MD-90-30 airplanes, that currently requires replacing the lanyards on the pressure relief door for the thrust reverser with new, improved lanyards, and doing associated modifications. The actions specified by that AD are intended to ensure that the lanyards on the pressure relief door have adequate strength. Lanyards of inadequate strength could allow the pressure relief door to detach from the thrust reverser in the event that an engine bleed air duct bursts, which could result in the detached door striking and damaging the horizontal stabilizer, and consequent reduced controllability of the airplane. This proposed AD is prompted by the fact that a certain paragraph of the existing AD prohibits installation of certain part numbers of lanyards; the numbers listed in that paragraph correspond to new, improved lanyards that are acceptable for installation. This action would correct these part numbers to prohibit installation of suspect lanyards while allowing installation of the new, improved lanyards. This action is intended to address the identified unsafe condition.