A Study of Measuring Indirect Effects of Lightning on Commercial Aircraft Engine Control Systems

Electromagnetic environments induce undesirable electromagnetic responses in control systems that deteriorate the functioning and operation reliability of control systems. Lightning, an external electromagnetic excitation of instantaneously high magnitude, is one of the most extreme electromagnetic environments whose indirect effects should be taken into consideration during control system development processes. As a necessity for flight safety, control systems in commercial aircraft engines are required to be immune to indirect effects of lightning to ensure stable and durable operations such as propulsion generation during the whole flight. This paper studies and measures indirect effects of lightning on commercial aircraft engine control systems in order to obtain control system level lightning transient immunity design requirements. A control system comprised of airborne electrical equipment and interconnecting multi-branched shielded cable harnesses is modeled for induced lightning transient measurement. Numerical case studies are conducted to study indirect effects of lightning and measure lightning transients, i.e. induced cable bundle currents, when the nacelle housing the engine control system is under cloud-to-ground and intra-cloud lightning strikes. The lightning transient measurements resulted from indirect effects of lightning will be defined as system-level design requirements to bridge the gap between lightning transient immunity design and validation processes.