AGEAIR (AGEing AIRcrafts) is a project targeting the effect of engine age on the emission performance of aircraft engines. Data available in the ICAO Engine Emission Database (EEDB) are based on new aircraft engines, and most scientific research on the emission performance of aircraft engines do not pay close attention to the deterioration effect of the tested engines. However, there are indications that the engine age may influence their gaseous and particulate emissions. Such information is important to better understand the impact of aviation on local air quality and global climate. Beyond the engine deterioration effect on local air quality, the emission properties of small to medium-sized helicopter and turboprop aircraft engines (turboshaft, turboprop) as well as of small turbojets remains, despite recent progress, largely unknown. Although the relative share of such small engines is negligible when considering worldwide aviation emissions, measurement of emitted pollutants contributes to a more holistic understanding of aviation’s impact on environment. AGEAIR aims at closing those two knowledge gaps with multiple engine test cell measurements at different locations with the help of SMARTEMIS.

AGEAIR I - Completed

The AGEAIR I project was officially closed in June 2020. AGEAIR I was initiated with the transfer of the Swiss Mobile Aircraft Emission Measurement System (SMARTEMIS) from Empa to ZAV under the stewardship of the ZAV’s Meteorology, Environment and Aviation research unit (METENVIA). The primary objectives of AGEAIR I were to build competence in aircraft emission measurements, emission data handling and interpretation within the research unit. After major maintenance of the SMARTEMIS infrastructure, emission measurements on aircraft engines undergoing maintenance tests at SR Technics were done to gain first insights into engine deterioration effect on emission properties.

Summary of AGEAIR I achievements:

• several SMARTEMIS training sessions alongside measurements at SR Technics,
• upgrade and major maintenance work of the SMARTEMIS system,
• improved documentation of the SMARTEMIS system with the creation of new operation checklists and drafting of a SMARTEMIS handbook
• emission measurements at the sites of external partners, local and international, mainly for engine certification purposes following the ICAO Annex 16, Volume II standard, participation in emission and measurement related meetings and conferences including SAE31 meetings, and
• initial assessment of previous emission data, which showed the complexity of the task of understanding the effect of engine age on emissions due to several confounding factors affecting engine emission

AGEAIR II - ongoing

AGEAIR II was initiated in July 2020. AGEAIR II first continues the work of AGEAIR I, investigating the effect of engine age on the emission performance of turbofan jet engines. AGEAIR II also continues the AGEAIR I task of maintaining and upgrading the SMARTEMIS infrastructure.

AGEAIR II however takes several steps further. AGEAIR II also aims to investigate the emission performance of non-regulated engines including turboshaft, turboprop and small turbofan engines, below the ICAO regulations’ maximum rated thrust limit (26.7kN). The goals of AGEAIR II are complemented by parallel projects of the METENVIA group such as the EU H2020 projects RAPTOR and ACACIA.

Update for AGEAIR II: First period

In 2020, the world of aviation is being hit by the unprecedented COVID-19 event. Though the pandemic also impacted measurements at SR Technics, there has been continuous work on the AGEAIR II project.

• SMARTEMIS expansion: The SMARTEMIS infrastructure has been expanded with the creation of a new gas rack, an extension of the already existing rack
• Work on building SMARTEMIS know-how and improved documentation has continued
• With calibrations conducted in October 2020, SMARTEMIS was out for two weeks in November and December 2020 in an international collaborative measurement campaign as part of the RAPTOR project and on-going training of the METENVIA team on aircraft emission measurements.

Update for AGEAIR II: Second period

2021 was a very successful year for the AGEAIR II project with respect to emission measurements. Following several updates to SMARTEMIS in the first period of AGEAIR II, we have conducted a total of 17 full engine thrust profile emission measurements at SR Technics alongside the maintenance tests on engines. In the meantime, we have a new member to the team working with SMARTEMIS, increasing the distribution of competence in operating, and maintaining SMARTEMIS.

In addition, there were several collaborative measurements with external and local partners. Two campaigns were conducted with a Japanese research group for the Japanese National Institute for Environmental Studies (NIES), involving the collection of exhaust samples on particle filters for composition analyses. In the light of the ACACIA project, in collaboration with a research group at ETH, exhaust particles were collected for experiments on the effectiveness of engine exhaust particles in ice nucleation. Also, in continuation of the RAPTOR project, the second RAPTOR campaign at the Gas Turbine Research Centre (GTRC) in Wales was conducted to close off the year’s emission measurements with SMARTEMIS.

In the following period, continuation of emission measurements is planned with focus on smaller and unregulated engines. We are also looking forward to the next measurement campaign within the ACACIA project and future collaboration within and outside Switzerland towards understanding jet engine emissions and impacts on the environment.

News on AGEAIR II: Third and fourth period

2022 and 2023 were also successful years in the emissions work of METENVIA within the scope of the AGEAIR II project. The emission measurements for the ACACIA project in collaboration with ETH and the APPROPRIATE project in collaboration with PSI were successfully conducted in 2022 at SR Technics.

In 2023, while SR Technics prepared for partial shutdown for renovations, METENVIA went for a field campaign in Payerne. At this campaign, with PSI, FOCA and the Swiss Airforce, emission measurements were conducted on the Swiss Air Force One (Citation campaign), comparing the emission performance of  its engines operating with Jet A1 and 30% SAF/Jet A1 blend (story on this measurement campaign). Preliminary assessment of the data indicates that there was a significant reduction (about 20%) in the particulate matter emissions with the use of SAF in the fuel mix.

AGEAIR II comes to an end in December 2023. To this effect, we are rounding up data analyses. Future publications are planned for final dissemination from the AGEAIR II project.

Outlook:
To continue the emissions research started in the AGEAIR projects, a new FOCA-funded project ADVISAR (Addressing feasibility studies towards cleaner aviation and environmental impacts research with SAF on unregulated engines) is set to start in January 2024. ADVISAR will focus on continuing the work started in the Citation campaign, i.e., assessing the changes in emission performance with the application of alternative fuels. ADVISAR will go further to investigate logistical bottlenecks in importing and distributing SAFs in Switzerland, the health impacts of emissions when using SAFs, and the effects of ambient conditions on emission performance with conventional and alternative fuel/fuel blends.