US Patent 7556221 Aircraft ice protection method

A method of removing a delay-induced ice accumulation (e.g., an ice cap) from an airfoil's leading-edge region with a zoned electrothermal device. The method comprises delay-rectifying steps which are performed prior to routine-deicing steps. The delay-rectifying steps comprise continuously heating the parting strip (PS), continuously heating the upper fore zone (UF1), and continuously heating the lower fore zone (LF1). These steps efficiently and effectively remove the delay-induced ice accumulation, whereby routine deicing can be resumed.