As sustainability is set to be a driving factor in the design of Boeing’s next new airliner, the testbed has assumed a key role.
Guy Norris
Credit: Boeing
The presence at this year’s Dubai Airshow of Boeing’s 737-9 ecoDemonstrator underscores both the technology testbed’s growing influence on the company’s long term development strategy and the increasing importance of sustainability initiatives to operators in the region.
The new environmental focus in the region is exemplified by Abu-Dhabi-based Etihad Airways which became the first Middle East carrier to announce a target of achieving net zero CO2 emissions by 2050. The airline launched its 787-10 Greenliner program in 2019 and the following year supported Boeing’s ecoDemonstrator campaign.
The Greenliner—also on display at Dubai—has been used to test sustainable technologies toward Etihad’s goal and in October the airline operated the aircraft on a special flight between London and Abu Dhabi to mark the program’s two-year anniversary. The flight used a blend of 38% sustainable aviation fuel (SAF), and the remaining carbon emissions were 100% offset.
The airline is also studying future options for sourcing varying SAF feedstocks as well as hydrogen by partnering with Abu Dhabi-based clean energy firm Masdar, Siemens and Marubeni of Japan. Etihad has also used the Greenliner to evaluate technologies such as Jeppesen’s FliteDeck Advisor—a navigation application to provide optimized routings.
Boeing’s 2020 ecoDemonstrator—which used another 787-10 on loan from Etihad—focused on areas related to measuring and reducing aircraft noise, a four-dimensional live flight demonstration for route optimization, and airspace efficiency and continuing evaluations of SAF. Sound measurement work was undertaken in partnership with NASA and validated processes used to predict community noise impacts.
Together with Safran Landing Systems, Boeing also used the Etihad aircraft to test landing gear modified with flow deflectors, or fairings, to assess the potential for reducing the noise made by the gear on the 787 as well as improve the noise signature of gear designs for future aircraft.
The current 737-9 ecoDemonstrator aircraft, which is expected to conduct flight tests through December, is configured with a variety of new technologies ranging from sidewalls made from recycled composites derived from 777X wing-production waste to a low-noise, aft fan duct design suitable for a compact engine nacelle.
The latest test program marks only the second use of a 737 variant in the ecoDemonstrator program which began in 2012 with a 737-800 loaned from American Airlines. Since then, the initiative has tested an expanding series of technologies on a 787-8, 757-200, Embraer E-170, 777F, 777-200 and the Etihad-loaned 787-10.
The current ecoDemonstrator has continued the program’s long-running evaluation of SAFs, an initiative which gave the manufacturer confidence in its ability to certify all its products to use 100% SAF by 2030, a plan announced in January this year.
The 737-9 has also been used for ground tests of a new fire extinguishing agent for aircraft that is intended to replace Halon 1301, which is no longer being produced. Although non-Halon solutions have been found for cabins and lavatories, the industry is still forced to recycle Halon until effective replacements can be developed for the unique challenges of fire suppression at altitude in engines, APUs and the cargo hold.
While the 2019 ecoDemonstrator tested a new blend of bromotrifluoropropene (BTP) developed by Boeing and fire suppression specialists Meggitt, which showed promise for use in cargo holds, the Alaska 737-9 is specifically testing a Meggitt-developed agent dubbed CF3i (iodotrifluoromethane) for extinguishing engine bay fires. In particular, the ecoDemonstrator has been used to evaluate the flow during ground runs with the left Leap-1B engine at high power which simulate some of the hardest conditions for meeting extinguisher agent concentration requirements.
The program has also tested acoustic lining concepts in the aft fan duct of one of the aircraft’s CFM Leap-1B engines to evaluate potential noise reductions on current engines as well as inform designs for next-generation models. Conducted in conjunction with the FAA’s Continuous Lower Energy, Emissions and Noise (Cleen) program, the tests focused on treated thrust reverser blocker doors as well as specially developed acoustic gloves between the centerbody of the aft fan bifurcation duct and the inner walls of the thrust reverser.
Boeing says flight tests validated the design concept and pave the way for savings of up to 0.6 EPNdB on retrofit packages for current engines, as well as noise reductions of up to 1.2 EPNdB or more for ultra-high bypass engines on future aircraft for 2025 onward.
The 737-9 test work also includes collaboration with the U.S. National Oceanic and Atmospheric Administration to measure greenhouse-gas levels in the atmosphere to support the agency’s climate modeling and long-term forecasting.
As part of the drive to reduce life-cycle environmental impact, the cabin interior is partially configured with sidewall panels made from recycled carbon composite material salvaged from the 777X wing production site in Everett, Washington. Testing has focused on the acoustic properties of the panels which are considered rare examples of recycling for high value aerospace components.
The ecoDemonstrator is also being used for tests of a portable ultraviolet emitting box in the cabin ceiling to sanitize the interior. “We are really focused on the continuation of the confident travel initiative,” says Lutter, who adds the tests build on earlier technology including a Boeing-developed UV wand which was validated on the 2020 ecoDemonstrator. The wand is now manufactured by Florida-based lighting specialists Healthe and Far UV of Missouri. The device uses 222 nanometer UV wavelength light to kill pathogens withMissouri-based Far UV out harming human skin tissue.
The ecoDemonstrator is also being used to evaluate enhanced ai traffic management connectivity with Inmarsat’s Iris datalink satcom system. The current tests follow trials of a baseline internet protocol suite communications management unit on the 2019 ecoDemonstrator, a 777-200, and together represent the first trial of end-to-end cockpit to ground internet protocol satellite communications for more efficient operations.
Touchscreen cockpit display units (CDUs) are also under trial in ecoDemonstrator, building on earlier tests in 2014 which led to the introduction of the technology on the 777X. If all goes well, Boeing says the touch screen CDUs could also enable some other cockpit radio panels to be deleted and the system could form the basis of a future flight deck upgrade for the MAX.
