Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain McDonnell Douglas Model MD-90-30 airplanes. This proposal would require measuring the length of the wear indicator on the brake stack of the main landing gear (MLG) brake assembly to determine the degree of wear, and follow-on actions. This proposal also would require eventual replacement of the existing MLG brake assembly with a new, improved or modified assembly, which would constitute terminating action for any repetitive actions being performed per this proposed AD. This action is necessary to prevent failure of the MLG brakes and consequent loss of braking capability, which could result in the airplane overrunning the runway during take-off or landing. This action is intended to address the identified unsafe condition.