Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Boeing Model 757 and 767 series airplanes. This proposal would require inspection to determine the serial number of the hydraulic pump in the ram air turbine (RAT), and corrective action, if necessary. This action is necessary to prevent a cracked hanger arm of the hydraulic pump of the RAT that can fracture under load and lead to failure of the RAT to provide hydraulic power to the primary flight control system during an emergency when both engines have failed. Loss of hydraulic power to the primary flight controls could result in loss of control of the airplane. This action is intended to address the identified unsafe condition.