Modern aircraft are well equipped to safely fly in almost any kind of weather. But some hazardous conditions have gone unnoticed for a few decades, resulting in several unresolved accidents. Supercooled large droplets (SLD) and ice crystals were discovered as the culprit following 2 such accidents, prompting authorities to issue new certification requirements in 2015 to address aircraft safety concerns.
The NRC's Altitude Icing Wind Tunnel is one of few wind tunnels in the world capable of simulating supercooled large droplets and ice crystal conditions. It makes it an ideal facility for assessing the effects of icing on the performance of aircraft sensors and ice detectors, aircraft surfaces, components and probes. With these capabilities and the NRC's Aerospace Research Centre's internationally renowned expertise, the SENS4ICE project sought out the NRC's participation in testing and validating new icing condition detection techniques in assessing the risk of icing conditions on aircraft safety. The NRC joined the consortium in January 2021 and has already conducted tests on sensors with 4 different partners.
SENS4ICE, which stands for sensors and certifiable hybrid architectures for safer aviation in icing environments, is focussed on developing reliable techniques for detecting icing conditions. The consortium comprises 20 international partners. The project addresses the development, testing, validation and maturation of individual detection principles, as well as the combination of different ones. It also assesses demonstrations of the technology capabilities in relevant natural icing conditions. The consortium works closely throughout the project with regulators to ensure that the new technologies meet the regulatory requirements.
The SENS4ICE project also works with 4 other wind tunnel facilities around the world: the Collins Aerospace Icing Wind Tunnel (USA), the Technical University of Braunschweig Icing Wind Tunnel (Germany), and the 2 Russian TsAGI facilities, the Climatic-type Icing Wind Tunnel AHT SD and the Year-round Icing Wind Tunnel.
The NRC's in-house sensors
Not only is the NRC's Aerospace Research Centre testing third-party sensors, but they also developed some of their own! A team led by Dan Fuleki, Project Manager at the NRC's Gas Turbine Lab, is working on 2 such prototypes.
The first sensor, called the ultrasound ice accretion sensor (UIAS), is the result of an innovative collaboration between the NRC's Aerospace and Energy, Mining and Environment Research Centres. It uses ultrasound waves to detect ice on a surface. It is non-intrusive, lightweight, consumes very low power, and can quantify the build-up of frost and ice at, and between, each sensor. The second one, called the particle detection probe (PDP), uses local electrical conditions to detect ice crystals in the air. So far, it has been tested for over 90 hours on 3 different aircraft: the Airbus A340, the NRC Convair 580 and the NRC T33.
Both of these sensors are being tested in the NRC's Research Altitude Test Facility, which reproduces atmospheric ice crystal icing (ICI) conditions. The facility has been running atmospheric ice crystal icing tests since 2008 and is used to study loss in performance and damage experienced by aircraft instruments and engines when exposed to icy conditions.
The development of these 2 sensors allowed the NRC to fully understand the issues and challenges associated with the measurements of supercooled large droplets and ice crystals. The particle detection probe and ultrasound ice accretion sensor both address the needs of a large market that includes everything from commercial aircraft to regional and business jets to turboprop aircraft, urban air mobility and unmanned air vehicles. The NRC is now looking for partners and collaborators to commercialize these new technology offerings.
Capitalizing on the NRC's research and development capabilities puts Canada in the perfect position to be the international industry's premier research partner in accelerating the race towards safer flight technologies.