Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Boeing Model 727 series airplanes that have been converted from a passenger to a cargo-carrying (``freighter'') configuration. This proposal would require, among other actions, installation of a fail-safe hinge, redesigned main deck cargo door warning and power control systems, and 9g cargo barrier. This proposal is prompted by the FAA's determination that the main deck cargo door hinge is not fail-safe; that certain main deck cargo door control systems do not provide an adequate level of safety; and that the main deck cargo barrier is not structurally adequate during an emergency landing. The actions specified by the proposed AD are intended to prevent structural failure of the main deck cargo door hinge or failure of the cargo door system, which could result in the loss or opening of the cargo door while the airplane is in flight, rapid decompression, and structural damage to the airplane; and to prevent failure of the main deck cargo barrier during an emergency landing, which could injure occupants.