As large commercial aircraft continue to attempt to decrease their bleed air demands and smaller aircraft look for more efficient and higher performing ice protection systems (IPS) the industry must look at new solutions.
One method used to improve upon current system IPS is to combine the strengths of multiple ice protection methods to create a hybrid system which offsets the disadvantages of the various system types. This paper looks at the creation of a hybrid system by combining a freezing point depressant (FPD) system with an electrothermal de-ice system.
The use of freezing-point depressant and electrothermal ice protection systems have been well established in the aviation industry. Both types of systems have been certified on Part 23 and Part 25 aircraft and are in use today. One of the major challenges for an electrothermal IPS is the power generation required to achieve certifiable performance over the entire FAR Part 25 Appendix C Icing Envelope. This is especially critical in the coldest temperature areas of the Icing Envelope. For an FPD system one of the perceived challenges is the weight of the fluid required to be carried to meet regulatory requirements and ensure appropriate system endurance.
The benefits of combining freezing point depression with electro-thermal is evident in the net savings of electrical power versus the overall requirement of fluid for protection, making it an efficient and practical solution for commercial aircraft.