Summary
The FAA proposes to adopt a new airworthiness directive (AD) for certain Airbus Model A320 series airplanes. This proposed AD would require post-maintenance bleeding of accumulated air from, or ground functional testing of, the ram air turbine (RAT) system; modifying and reidentifying the airborne ground check module of the RAT system; and replacing the RAT reducer assembly if applicable. This proposed AD is prompted by reports of unsuccessful in-flight RAT tests during which a deployed RAT failed to pressurize the blue hydraulic circuit of the RAT system. We are proposing this AD to prevent failure of the RAT during an in-flight emergency, which could lead to loss of hydraulic and electrical power and reduced controllability of the airplane.