The first Aircraft Particle Emissions Experiment (APEX) test was conducted in April 2004 to collect a set of gaseous and particulate emissions data from an in-service commercial engine. APEX is a collaborative research effort of NASA, EPA, and DoD. Its main objective is to advance the understanding of particle emissions by characterizing gaseous and particulate emissions of NASA's DC-8 with CFM-56-2C1 engines. Gaseous and particulate emissions were acquired by researchers and engine operating parameters were defined with assistance from manufacturers. The various participants in the APEX project have undertaken numerous activities such as (a) examining the effect of engine thrust on particulate emissions, (b) simulating emissions at airports, and (c) studying fuel effects on particulate emissions by varying fuel composition. APEX2 was conducted in August 2005, and APEX3 was conducted in October-November 2005. In APEX2, the aircraft-engine combinations tested were two B737-700s with CFM56-7B24 engines and two 737-300s with CFM56-3B1 engines. In APEX3, the aircraft and engines tested were a Learjet25 with CJ610 engines, an A300-600 with PW4158 engines, two B757s with RB211-535E4B Phase 5 engines, an ERJ14-XR with AE3007-A1E engines, an ERJ with AE3007-A1P engines, and a B737-300 with CFM56-3 engines.
In addition to the gas and particle emissions measurements from static aircraft tests, there were two occasions when emissions were measured far downstream on the side of an active runway during aircraft taxi and take off. One of these was at Oakland International Airport during the JETS-APEX2 test, and the other was during a test at an Unnamed Airport with an Unnamed Airline (UNA-UNA)*. These sets of data provide various snapshots of a wide range of different airplanes under normal airport operations.
Substantial gaseous and particulate emissions data have been obtained from in-service aircraft in this series of tests, collected at a cost of almost $4 million. The current volume of data is extensive and additional interpretation is required in order for it to be used appropriately by the airport community and general public.
Aviation emissions contribute toward ambient levels of air pollutants identified under the Clean Air Act that are considered harmful for public health and the environment. In order to assess the potential impacts of aviation emissions, characterization and quantification of aircraft engine emissions are essential. While conducting airport health and environmental risk assessments is outside of the scope of this project; it will provide foundational data and analyses that will help to clarify how these data can and cannot be used.
The objective of this research is to summarize, analyze, and interpret the scientific data available from the Aircraft Particle Emissions Experiment (APEX) 1-3 and the Unnamed Airport-Unnamed Airline (UNA-UNA)* experiment. The results will be presented in a comprehensive report to help the airport community and general public understand the data's ability to contribute to developing better air quality assessments in the airport environment.
Status: The revised final report for this project is published as ACRP Report 9: Summarizing and Interpreting Aircraft Gaseous and Particulate Emissions Data.
* UNA-UNA is now known as the Atlanta Hartsfield International Airport-Delta Airlines test