Special Conditions: Airbus Model A350-900 Airplane; Lightning Protection of Fuel-Tank Structure To Prevent Fuel-Tank Vapor Ignition

These special conditions are issued for Airbus Model A350-900 airplanes. These airplanes will have a novel or unusual design feature that will incorporate a nitrogen generation system (NGS) for all fuel tanks, to actively reduce flammability exposure within the fuel tanks significantly below that required by the fuel-tank flammability regulations. Among other benefits, the NGS significantly reduces the potential for fuel-vapor ignition caused by lightning strikes. The applicable airworthiness regulations do not contain adequate or appropriate safety standards for this design feature. These special conditions contain the additional safety standards that the Administrator considers necessary to establish a level of safety equivalent to that established by the existing airworthiness standards.