Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain McDonnell Douglas Model MD-11 series airplanes. This proposal would require inspections to detect damage of the sidewall vent box diaphragms, and repair, if necessary. This proposal also would require eventual installation of stops on the vent box diaphragm, which would terminate the inspection requirements of the proposed AD. This proposal is prompted by reports of damage to sidewall vent box diaphragms, which can result in non- functional diaphragms during a rapid decompression. The actions specified by the proposed AD are intended to prevent buckling of the floor beams due to insufficient air flow of the cabin sidewall vent box diaphragms during rapid decompression, and subsequent reduction in the controllability of the airplane.