Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Boeing Model 747 series airplanes. This proposal would require repetitive inspections to detect cracks and/or corrosion of the girt bar support fitting at certain main entry doors; and repair or replacement of the support fitting. This proposal would also provide for various terminating actions for the repetitive inspections. This proposal is prompted by reports that, during scheduled deployment tests of main entry door slides, corrosion was found on the floor structure supports for the escape slides of the main deck entry doors on these airplanes. The actions specified by the proposed AD are intended to prevent such corrosion, which could result in separation of the escape slide from the lower door sill during deployment, and subsequently prevent proper operation of the escape slides at the main entry doors during an emergency.