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For Release: August 19, 2004

Katherine K. Martin
Media Relations Office


The first and most extensive set of gaseous and particulate emissions data from an in-service commercial aircraft jet engine was obtained by a team of researchers from NASA, the Environmental Protection Agency (EPA), and the Department of Defense (DOD). This collaborative effort, called the Aircraft Particle Emissions eXperiment (APEX) Project, resulted in successful ground tests earlier this year at Edwards Air Force Base, Calif.

APEX's main objective is to characterize gaseous and particulate emissions of NASA's DC-8 airplane and its CFM-56 engines to advance the understanding of particle emissions from commercial aircraft engines.

Researchers are currently analyzing this set of data and planning a special meeting in November to discuss the preliminary conclusions.

According to Dr. Chowen C. Wey, APEX Project Manager and Environmental Assessment Manager for the Vehicle Systems Project Office at NASA's Glenn Research Center, who led the coordination of the tests, "Never before have so many agencies teamed to examine emissions from so many angles. This is the first step needed to reach a complete understanding of particle emissions from commercial aircraft engines."

In recent years, fine particulate emissions from aircraft have become increasingly important because they are identified as potentially contributing to global climate change and lowering local air quality. Incomplete combustion of hydrocarbon fuel in gas turbine engines results in production of small particles comprised mostly of solid carbon, known as soot, and non-volatile organic compounds. Engine erosion and trace metal impurities in jet fuel also create metal particles that are emitted in the engine exhaust. Additionally, volatile aerosols of sulfur compounds and organics are formed as engine exhaust cools.

The international aviation community is interested in the potential effects of these emissions and it has specified measurement technology and identified possible limitations and controls. Regulatory agencies have likewise begun to examine methods for measuring particle emissions from aircraft gas turbine engines. "Current international regulations regarding visible smoke do not address and are not relevant to the measurement of particles responsible for health effects and environmental impact," said Wey.

APEX had two different sets of goals for the test: for NASA, it was to investigate the engine thrust's effect on particulate emissions. This was done by varying engine operating parameters. At the same time, the EPA used a Landing-Take-Off cycle defined by the International Civil Aviation Organization to simulate aircraft emissions at the airport. In addition, fuel effects on particulate emissions were explored by using three different fuels -- baseline, high-sulfur, high-aromatic.

Researchers at these institutions are taking part in collecting the data: NASA Glenn Research Center, Cleveland; NASA Langley Research Center, Hampton, Va.; NASA Dryden Flight Research Center, Edwards, Calif.; General Electric Aircraft Engines, Evendale, Ohio; The Boeing Company, Seattle; Southwest Research Institute, San Antonio; Arnold Engineering Development Center, Arnold AFB, Tenn.; University of Missouri, Rolla, Mo.; Aerodyne Research, Inc., Billerica, Mass.; EPA, Research Triangle Park, NC; Wright Patterson Air Force Base, Dayton, Ohio; University of California, Riverside, Calif.; and Process Metrics, Inc., San Ramon, Calif.

A majority of funding for these tests and analyses was provided by NASA's Vehicle Systems Program, whose goal is to pioneer and validate ground breaking capabilities to protect the environment, make Americans more mobile, support national security, and enable new missions. Reduced noise and air pollution, as well as higher efficiency and completely new air vehicle concepts, are the key goals of the Program.

For more information on the Vehicle Systems Program on the Internet, visit:



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