Special Conditions: Boeing Model 747-100/200B/200F/200C/SR/SP/100B/300/ 100B SUD/400/400D/400F Airplanes; Flammability Reduction Means (Fuel Tank Inerting)

These special conditions are issued for the Boeing Model 747- 100/200B/200F/200C/SR/SP/100B/300/100B SUD/400/400D/400F series airplanes. These airplanes, as modified by Boeing Commercial Airplanes, include a new flammability reduction means that uses a nitrogen generation system to reduce the oxygen content in the center wing fuel tank so that exposure to a combustible mixture of fuel and air is substantially minimized. This system is intended to reduce the average flammability exposure of the fleet of airplanes with the system installed to a level equivalent to 3 percent of the airplane operating time. The applicable airworthiness regulations do not contain adequate or appropriate safety standards for the design and installation of this system. These special conditions contain the additional safety standards the Administrator considers necessary to ensure an acceptable level of safety for the installation of the system and to define performance objectives the system must achieve to be considered an acceptable means for minimizing development of flammable vapors in the fuel tank installation.