Summary
This document proposes the supersedure of an existing airworthiness directive (AD), applicable to certain British Aerospace (Jetstream) Model 4101 airplanes, that currently requires repetitive detailed visual inspections to detect cracking or other damage of certain diaphragm support structures of the forward equipment compartment; and repair, if necessary. This action would continue to require repetitive inspections, but would also require replacement of cracked or damaged diaphragm support structures with improved parts, which would terminate the requirement for repetitive inspections. This action also would add airplanes to the applicability of the proposed AD. This proposal is prompted by the development of improved diaphragms. The actions specified by the proposed AD are intended to prevent failure of the two diaphragms that support the upper structure of the forward equipment compartment, which could accelerate fatigue damage in adjacent structure and result in reduced structural integrity of the airframe.