This Aerospace Recommended Practice (ARP) consists of methodologies for the measurement of non-volatile particulate matter (nvPM) emissions at the exit plane of aircraft gas turbine engines. The methods describe means of sampling and measuring particle mass concentration, particle number concentration and reporting of emissions indices through the use of an appropriate sampling system and instrumentation that goes beyond the measurements of visible obscuration as described in ARP 1179 for Smoke Number (SN).
Particulate matter (PM) exhaust from aircraft turbine engines is currently assessed by the measurement of the Smoke Number (SN) as described in ARP 1179. The SN was developed to ensure compliance with an aircraft engine exhaust visibility criterion; however, it has limited use in newer/cleaner engines, and does not address the current need to quantitatively measure the mass and number of PM emitted from the engine. This ARP outlines the requirements for the sampling system, mass and number measurements, provides equations for emission indices calculations and explains how to check for compliance, maintain, and operate a non-volatile PM system.