FAA Announces Sustainable Aviation Research Contracts

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The FAA has issued research contracts worth more than $100 million to six aerospace partner companies and teams under the third phase of its long-running Continuous Lower Energy, Emissions and Noise (CLEEN) Program.

Launched in 2010, the CLEEN initiative forms the FAA’s main environmental effort to accelerate the development of technologies to reduce aircraft noise, emissions and fuel burn. According to the U.S. Transportation Department, technologies already developed under the first two phases will save the industry an estimated 36 billion gal. of fuel by 2050.

The latest contracts, which are public-private partnerships under which each company contributes at least a 100% cost share to the program, are aimed at environmental targets which build on the earlier phases. The noise reduction goal for Phase III is a 25 dB cumulative noise cut relative to Stage 5 limits—the same as Phase II—but adds reductions in community noise exposure. The fuel burn goal is 20% below the latest CAEP/10 CO2 international standard and the target for nitrogen oxide (NOx) emissions reduction is a 70% margin to CAEP/8 landing and take-off limits. 

As well as adding targets for reducing community noise exposure, Phase III also introduces the goal of cutting back emissions of particulate matter relative to the CAEP/11 standard. For the first time the program also includes reduced landing and take-off noise levels for civil supersonic aircraft as well as a target for reducing absolute NOx emissions over the aircraft’s mission.

Phase III also includes a significant new focus on new and sustainable jet fuels that could provide reductions in emissions or improvements in efficiency, including fuels—and blends of fuel—that enable advancements in aircraft and engine design. The FAA says this includes both conventional and alternative jet fuels. “The CLEEN Program is interested in fuels that are drop-in compatible with the existing pipeline and airport fueling infrastructure but have changes in their composition that could help an aircraft meet the CLEEN Program goals,” says the agency.

All the technologies for meeting these goals are targeted at entry-into-service in 2031. Technologies developed under CLEEN II are targeted at service entry in 2026, while various technologies tested under Phase I—ranging from advanced combustors and acoustic treatments to optimized flight path navigation—have already entered operation.

Contract Awards

Specific contracts have been awarded to Boeing for evaluation of alternative fuels as well as for further development of airframe and engine inlet noise reduction technology. The company will also continue on-going development of new algorithms that enable quieter, more fuel-efficient routes. Boeing is currently flight testing a quieter aft fan nacelle duct developed under Phase II for the CFM LEAP-1B on its latest ecoDemonstrator, a 737-9.

General Electric will focus on an advanced engine propulsion system and advanced acoustic improvements to reduce noise and fuel consumption building on acoustic liner, fan noise research and combustor work from earlier CLEEN phases. The CLEEN contract also includes additional research on electric and hybrid-electric systems as well as thermal management systems already underway as part of GE’s Mestang (more electric systems and technologies for aircraft in the next generation) program. GE will also continue evaluation of alternative jet fuels under Phase III.

Under Phase III, Honeywell Aerospace will develop a more efficient engine fan, combustion system, compressor, and turbine. The work builds on Phase II work, much of it still underway, which focused on tests of a compact lightweight combustor, development and endurance evaluation of a low leakage turbine air seal, tests of a new low-noise fan and liner, and an advanced high-pressure compressor.

Pratt & Whitney will develop an ultra-quiet engine fan and an advanced combustion system to reduce noise, emissions, and fuel consumption. The fan work for Phase III will leverage the advanced fan system testing for the PW1000G geared turbofan completed in 2017 under the original Phase I. The company already plans to integrate elements of Phase II technology into the PW1000G family, including improved high-pressure compressor and turbine aerodynamics and cooling.

A team involving Delta TechOps, GKN Aerospace, MDS Coating, and America’s Phenix will work together to develop erosion-resistant fan blade coatings to reduce fuel consumption over the life of an engine. The new contract continues evaluations of advanced coatings which were flight tested under Phase II on a Pratt & Whitney JT8D-powered MD-80, and which were estimated to have saved up to 0.4% fuel savings during cruise and over 1% at maximum power. In addition to the JT8D, coatings were also tested at component level on PW2037 and GE CF6 engines.

Rohr, a wholly owned unit of Raytheon’s Collins Aerospace division, will develop acoustic technology to reduce the engine exhaust noise under Phase III. The company previously worked with Raytheon (formerly United) Technologies Research Center under Phase II on new acoustic liners, low drag ducts and liner designs and a short, reduced drag inlet.   

The FAA says it is also “pursuing agreements” with Rolls-Royce and Safran Nacelles. Under Phase II, Rolls developed and tested an enhanced low NOx emissions combustor design and evaluated fully synthetic jet fuels. It also completed ground tests with Boeing of a short duct nacelle on a Trent 1000 which paved the way for flight tests this year on the engine company’s 747-200 flying testbed.

Guy Norris

Guy is a Senior Editor for Aviation Week, covering technology and propulsion. He is based in Colorado Springs.