Summary
The FAA proposes to supersede an existing airworthiness directive (AD) that applies to certain Airbus Model A300-600 series airplanes. The existing AD currently requires an inspection for evidence of chafing between the hydraulic flexible hose and the ram air turbine (RAT) hub, and related investigative and corrective actions if necessary. This proposed AD would extend the applicability to include all A300-600 series airplanes that are equipped with a certain RAT. This proposed AD results from reports of holes in the RAT hub cover. We are proposing this AD to prevent a hole in the RAT hub cover. A hole in the RAT hub cover could allow water to enter the RAT governing mechanism, freeze during flight, and jam the governing mechanism. In addition, the metal particles that result from chafing between the hydraulic flexible hose and the RAT could mix with the lubricant grease and degrade the governing mechanism. In an emergency, a jammed or degraded RAT could result in its failureto deploy, loss of hydraulic pressure or electrical power to the airplane, and consequent reduced controllability of the airplane.