Airworthiness Directives; Airbus Model A300 B4-600R Series Airplanes, A300 C4-605R Variant F Airplanes, A300 F4-600R Series Airplanes; and Model A310-300 Series Airplanes

The FAA is adopting a new airworthiness directive (AD) for certain Airbus transport category airplanes. This AD requires replacing the existing vent float valve with a new, improved vent float valve. This AD results from reports of failure of the vent float valve in the left-hand outboard section of the trimmable horizontal stabilizer. We are issuing this AD to prevent, in the event of a lightning strike to the horizontal stabilizer, sparking of metal parts and debris from detached and damaged float valves, or a buildup of static electricity, which could result in ignition of fuel vapors and consequent fire or explosion.