The Aerospace Recommended Practices of this document are intended for nitrogen-based Flammability Reduction Means (FRM) implemented on transport category, turbine powered airplanes. The recommended practices herein, therefore, relate only to the transport category aircraft, and focus specifically on contemporary inerting systems equipment. Such systems are referred to a Fuel Tank Inerting Systems (FTIS) in this document. This document does not cover the following:

• Military aircraft applications
• Air separation technologies other than hollow fiber membrane (HFM) and pressure swing adsorption (PSA)
• Inerting of conventional unheated wing tanks or aircraft dry bays
• Expected future technology solutions for the generation of inert gas.

The advice contained in this document is aimed towards providing aircraft manufacturers with guidance on the key issues associated with contemporary aircraft fuel tank inerting systems to supplement the guidance in FAA Advisory Circular AC 25.981-2. This document also provides system and component designers and manufacturers with advice on what aspects must be evaluated and addressed when designing a safe, low risk solution for transport aircraft fuel tank Flammability Reduction Means. As such, the information herein is intended as a guide for some system design aspects, but primarily identifies the issues which must be addressed in designing an inerting system for fuel tank flammability reduction.