Transport i lotnictwo · 06/08/1996

Airworthiness Directives; Boeing Model 757 Series Airplanes

This document proposes the adoption of a new airworthiness directive (AD) that is applicable to all Boeing Model 757 series airplanes. This proposal would require the replacement of certain discrepant ram air turbine (RAT) deployment actuator assemblies with units that have been modified and shipped in a specific fashion prior to installation. This proposal is prompted by reports that the RAT deployment actuators have failed to deploy upon command, due to interference in the actuator locking mechanism, which was caused by damage incurred during shipping of the actuator assembly. The actions specified by the proposed AD are intended to ensure that the RAT is deployed when commanded to do so. Failure of the RAT to deploy, specifically during a dual engine failure, would result in loss of hydraulic power, which would adversely affect the continued safe flight and landing of the airplane.