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This SAE Aerospace Recommended Practice (ARP) describes the continuous sampling and analysis of gaseous emissions from aircraft gas turbine engines. The measured gas species include carbon monoxide (CO), carbon dioxide (CO2), nitric oxide (NO), nitrogen dioxide (NO2), hydrocarbons (HC), and water vapor (H2O). This ARP excludes engine operating procedures and test modes, and is not intended for in-flight testing, nor does it apply to engines operating in the afterburning mode. It is recognized that there will probably be major advances in the gas analysis measurement technology. It is not the intent of this ARP to exclude other analysis techniques, but to form the basis of the minimum amount of conventional instruments (those in common industry usage over the last fifteen years) required for the analysis of aircraft engine exhaust.

This Aerospace Information Report (AIR) describes the use of FTIR analyzers for measurements of gaseous emissions from aircraft gas turbine engines and combustion rigs. The use of FTIR analyzers can be demonstrated as a suitable and cost-effective equivalent to NDIR and chemiluminescence analyzers as prescribed in ARP1256 for the measurement of CO, CO2, NO, and NO2, where NOx is closely approximated by the sum of NO and NO2 concentrations. FTIR analyzers may be proven suitable for equivalency of analyzers used in current emission testing. Additionally, FTIR analyzers have potential for equivalent measurements of “total” hydrocarbon (THC) as currently defined in ARP1256.

This report describes the concept and data analysis of the probe factor (pf) scheme. Conclusions are drawn and recommendations made for action to further the requirements for improved methods and procedures in emissions sampling technology.