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Joint Effort Develops New Method to Test Jet Emissions

Navy NewsStand

Story Number: NNS060809-10
Release Date: 8/9/2006 4:16:00 PM

By Victoria Falcon, Naval Air Systems Command Public Affairs

PATUXENT RIVER, Md. (NNS) -- Naval Air Systems Command partnered with government authorities, scientists, and engineers in 2004 to create a new test methodology to measure particulate matter (PM) emissions from aircraft gas turbine engines.

Until the new test is complete, an interim PM emissions test, which is based on lessons learned from tests run in 2004 and 2005, will save more than $1 million, three weeks of test cell time and more than 200 hours of engine run time per test, while providing more accurate data for the further development of a final test procedure.

“We’re working with the global aircraft emissions testing community, including JSF (Joint Strike Fighter), DoD, EPA, the FAA (Federal Aviation Administration), and NASA (National Aeronautics and Space Administration), engine manufacturers GE and Pratt and Whitney, academia and several U.S. and international organizations,” said Curtis Kimbel, program manager for Particulate Matter Test Plan Approval. “We are investigating a new method to test aircraft PM emissions that will be applicable to all jet aircraft – both military and commercial. The new method, in addition to being an improvement scientifically, will save time and money, and is expected to provide a more representative emissions profile than existing test methods.”

The out-dated method previously used to measure PM emissions was a modification to U.S. EPA Test Method 5. “Method 5” was originally developed in the 1950s for testing emissions from smokestacks and is an expensive, time-consuming process that yields questionable and incomplete results when applied to jet aircraft engines.

“A method developed for a stationary source, such as a smoke stack, cannot adequately address a mobile source, such as a military jet,” said Jean Hawkins, the JSF Environmental, Safety, and Occupational Health team lead.

“Because of the large flow area required by the engine and the high velocities of the exhaust flow, there are no existing JSF test cells that can strictly follow the EPA Method 5 requirements,” added Hawkins, who is also charged with insuring that the JSF program is capable of demonstrating compliance with the Clean Air Act. “Right now we’re developing what we expect will be a state-of-the-science measurement protocol for emissions profiling. This joint effort will benefit all stake-holders in the end. By being involved early-on, we are able to make changes along the way as we develop an EPA sanctioned protocol which can become an industry standard.”

Given that the JSF Program is seeking a near term alternative to Method 5 and the measurement and analytical techniques required to fully understand the volatile portion of the exhaust are still several years away, the team is focusing on the development of an interim PM test method.

The EPA has agreed to accept the state-of-the-science for this interim method while the team continues to pursue a permanent methodology.

“The current state-of-the-science with the new test is evolving quickly,” explained Kimbel, “and it is already significantly better than the expensive, time consuming EPA Method 5.”

The new method should be available during Spring 2007, and requires testing of only one engine for a few hours, which is a tremendous savings compared to Method 5, which costs $1.5 million per test, requires three-to-four weeks of test cell time, and the running of three engines 80-100 hours each.

“Our inter-agency team will use peer review and accept the test method and the data as we move forward,” said Kimbel.

That acceptance team has representatives from a wide variety of organizations, including the EPA, the JSF, DOD, NAVAIR, NASA, the FAA and the Society of Automotive Engineers (SAE) Aircraft Exhaust Emissions Measurement Committee (E-31), which is coordinating its work with the United Nations International Civil Aviation Authority (ICAO). The ICAO committee is the global PM testing community responsible for developing test procedures for measuring aircraft PM emissions for gas turbine engines used by commercial and military aircraft engine manufacturers.

According to Andersen, sharing information via the E-31 committee will accelerate the science of PM testing and provide aircraft engine manufacturers with new information that may allow future engines to be more fuel efficient while generating fewer emissions.

“The EPA will accept the experimental test results as satisfying JSF emission validation requirements under the Clean Air Act if EPA’s review and evaluation confirms the scientific validity of the interim methods and resulting data,” said Andersen.

Upon receiving EPA approval of the interim PM test method for the JSF, the Navy will work with the EPA to apply the improved test method to the Navy’s new upgraded H-53 Heavy Lift helicopter, a multimission antisubmarine aircraft (P-8A MMA) and an upgraded T-45 Trainer jet that will also require PM data.

“Our goal is to be able to scientifically demonstrate our emissions contribution to air quality,” said Hawkins.

“The work we are doing will enhance our understanding of a jet engine’s combustion chemistry,” Kimbel agreed, “and will eventually lead to the development of cleaner, more efficient aircraft engines for both military and commercial applications.”

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