Collaborating with industry partners to respond to aircraft icing
Aircraft icing resulting from liquid water in clouds has been a concern of the aviation industry for decades. More recently though, research and technology development has been focused on the risks related to ice crystals in clouds. Even when present in high concentrations, these ice crystals remain invisible to airborne weather radar. Ice crystals can clog or damage engines and block or foul pitot tubes – used to measure aircraft speed –initiating a dangerous sequence of events that at least once ended tragically.
Recently implemented regulations in Europe and North America require aircraft manufacturers to address the issue of ice crystal icing environments. An initial understanding of this problem and its many factors prompted the European Commission to fund the High Altitude Ice Crystal (HAIC) project created by Airbus in 2012. Since preventing aircraft icing is a broad industry necessity, the project engaged many research organizations and industries with the common goal of allowing aircraft to operate safely in these atmospheric conditions. The National Research Council of Canada (NRC), one of 34 partners from 15 countries, had the key task to provide and enhance ice particle detection and awareness technologies for use onboard commercial aircraft.
A 'best in class'
The NRC's Particle Detection Probe began as one of six candidate ice-detection technologies to be put through a rigorous selection process. Each technology had to perform well against certain criteria including weight, size, power consumption and drag. Ultimately, the Particle Detection Probe was one of only two detection probes that passed each stage during the project and operated throughout the entire flight campaign.
The Particle Detection Probe's characteristics are well suited to the commercial aviation industry. As a small, lightweight device that is flush-mounted to aircraft or engine inlet surfaces, it has no deleterious effects on fuel consumption or aerodynamics. In addition, the commercial version is expected to require no more power than a cellphone. None of the other technologies tested compared to the low power consumption or the low aerodynamic penalty of the Particle Detection Probe.
The probe detects particles in the atmosphere around the aircraft by measuring changes in the electrical characteristics of the local atmosphere when in an ice crystal environment. It uses this capability to detect and measure the concentration of ice particles in ice crystal laden clouds. How this information is then used is up to the aircraft manufacturer: to detect and continue, or to detect and react (change route).
Up next ...
The probe has proven its capabilities in ice crystal conditions, having been exposed to over 750 hours of ice crystal altitude tunnel testing, and having successfully completed over 140 hours of flight time with four research flight campaigns on NRC and Airbus research aircraft. It has been verified in a range of natural ice crystal and liquid water conditions at the mid-latitudes around Ottawa and at equatorial latitudes, and has been tested at altitudes above 40,000 ft.
"Part of our project is to accumulate an extensive dataset, and during the last campaign on Reunion Island, significant and critical operational data were obtained. "Looking at all the tunnel and flight testing, the amount and quality of data is exceptional," says Dan Fuleki, Icing Group Project Manager at the National Research Council. "The probe's performance impressed Airbus so much that they requested it be kept on the Airbus 340 for its next flight campaign to detect and measure supercooled liquid water content. This added test, funded by Airbus, is beyond the scope of the original project but expands the testing envelope of the probe. Soon we will have an even more extensive dataset which will now include supercooled liquid water on the same aircraft."
"NRC is very fortunate to have been invited to participate in an international project of this scale," adds Fuleki. "Without the direction from Airbus, the collaboration of all the partners and funding from the European Commission, this kind of project would not happen as it is too costly and requires too many resources for a single organization."
In the face of a major aviation threat such as ice crystals, any ice detection system would have a number of hurdles to overcome. NRC's small, lightweight, low-power probe has proven its worth in addressing these problems. Throughout its icing wind tunnel and flight testing history, the Particle Detection Probe has demonstrated its capability and benefits in ensuring the highest level of aviation safety. It is now ready to leave the laboratory for introduction to the market to be incorporated into new aircraft, ultimately making flight safer for all of us.
The Particle Detection Probe project is supported through NRC's Reducing Aviation Icing Risk research program.