Instrumentation and automated control of aircraft leading edge temperature

During the process of flying an aircraft at an altitude in excess of 20,000ft, environmental conditions can lead to ice being accumulated on the control surfaces of the aircraft with temperature extremes that are lower than -40°C being a large contributing factor. Anti-icing systems in dated aircraft predominantly apply hot engine bleed air to regulate the temperature on the aircraft control surfaces. The Royal New Zealand Air force (RNZAF) P-3K Orion aircraft utilizes a manually activated control system for controlling and monitoring the leading edge anti icing requirements. This manually activated system is becoming unreliable and difficult to maintain, the aircrew are required to manually activate the control circuit and in some instances constant monitoring is required. This paper discusses an automated solution that applies a fuzzy logic control circuit to control flow control valves which in turn regulate the amount of bleed air passed through a wing cavity. The control for the system is provided by a mixed-signal field programmable microcontroller, the Silicon Laboratories C8051F020. Automatic regulation of the bleed air flow provides temperature stability at the required set point. This solution reduces the aircrew interaction, achieves efficient control of the engine bleed air, and provides additional data to the user.