Flammability Reduction Methods: Compliance Options Federal Aviation Administration Flammability Reduction Methods: Compliance Options AAR-440 Fire Safety Branch Wm. J. Hughes Technical Center Federal Aviation Administration

Reticulated Foam Advantages: 100% protection Passive System No model – no need for flight testing Disadvantages: Weight Fuel displacement Interference with maintenance Haz. Mat. When out of tank Certification issues: Foam pedigree Voiding Durability Interference in tank

Inerting with Stored CO2 Advantages: ? Disadvantages: Must be stored on aircraft Certification issues: Needed O2 concentration not known Fuel solubility Effect on pumps

Inerting with Exhaust Gas Advantages: Already produced on aircraft Disadvantages: How to obtain Certification issues: Needed O2 concentration unknown Contaminants unknown

Catalytic Inerting Advantages: Possible weight Less power from aircraft environmental Disadvantages: ? Certification issues: Needed O2 concentration not known Fuel solubility Effect on pumps

Rapid Ventilation Advantages: Cost Weight Disadvantages: Loss of fuel Environmental Need for in-tank monitoring Certification issues: Tank flammability verification

Misting Fuel Vapor Advantages: Possible weight savings Possible lower cost Disadvantages: Loss of fuel Environmental Safety issues Certification issues: Post crash implications Failure modes In-tank hydrocarbon measurements

Nitrogen Inerting Cryogenic Nitrogen High Pressure Stored Nitrogen Ground Based Nitrogen Two Flow Nitrogen Full Time On Demand Nitrogen

Cryogenic Nitrogen Stored: Too heavy Manufactured: Developing technology

High Pressure Stored Nitrogen Too Heavy

Ground Based Nitrogen Logistics Manpower

Two Flow Nitrogen Present system of Choice

Full Time On Demand Nitrogen Advantages: Less power from aircraft Environmental Disadvantages: Weight Vent valve