Development and Validation Testing of the Collins Ice Differentiator System in App C and App O Icing Conditions

Protecting against atmospheric icing conditions is critical for the safety of aircraft during flight. Sensors and probes are often used to indicate the presence of icing conditions, enabling the aircraft to exit the icing cloud and engage their ice protection systems. Supercooled large drop (SLD) icing conditions, which are defined in Appendix O of 14 CFR Part 25, pose additional risk to aircraft safety as compared to conventional icing conditions, which are defined in Appendix C of 14 CFR Part 25. For this reason, developing sensors that can not only indicate the presence of ice, but can also differentiate between Appendix O (App O) and Appendix C (App C) icing conditions, is of particular interest to the aviation industry and to federal agencies. Developing a detector capable of meeting this challenge is the focus of SENS4ICE, a European Union sponsored project. This paper summarizes the work that was done to develop the Collins Ice Differentiator System, an ice detection and differentiation sensor developed by Collins Aerospace while participating in the SENS4ICE Project. A series of five icing wind tunnel campaigns were completed with the goal of developing the system and refining the underlying detection algorithm. A sixth integration wind tunnel test was then carried out to test all the Collins Ice Differentiator System’s constituent parts together as a complete system. This integration icing wind tunnel test was followed by additional integration testing to ensure that the system would function correctly on-aircraft. Finally, a flight test was completed with the goal of seeking out natural icing conditions to evaluate the performance of the Collins Ice Differentiator System, and that of the other SENS4ICE sensors.