Airworthiness Directives; Airbus Model A300 B4-600, B4-600R, and F4-600R Series Airplanes, and Model A300 C4-605R Variant F Airplanes (Collectively Called A300-600 Series Airplanes)

The FAA is superseding an existing airworthiness directive (AD), which applies to certain Airbus Model A300-600 series airplanes. That 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 new AD extends the applicability to include all Model A300-600 series airplanes that are equipped with a certain RAT. This AD results from reports of holes in the RAT hub cover. We are issuing 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 failure to deploy, loss of hydraulic pressure or electrical power to the airplane, and consequent reduced controllability of the airplane.