Lightning is a high current and high voltage phenomenon that can statistically struck an aircraft during the flight once a year. It has been categorized by the organs of certification three different lightning effects on the aircraft : Lightning Direct Effects (LDE), Lightning Indirect Effects (LIE) and Fuel System. In particular, the Indirect Effects are the result of interaction of the electromagnetic fields that accompany lightning flash toward the aircraft causing dysfunctions or some damages in the internal electrical/electronic wiring equipments. This thesis focuses on the Lightning Indirect Effects (LIE) on a simplified 3D Digital Aircraft Mock-up model of C-27J in order to calculate the Transient Control Levels (TCL) in correspondence of a reduced to a minimum network wiring .