High intensity radiated field (HIRF) penetration in helicopters

Modern aircraft use digital systems to control life-critical functions. These digital flight control systems are vulnerable to external phenomena such as high-intensity radiated fields (HIRF). Modern integrated circuits with higher densities and speed are more sensitive to HIRF; also, composite materials provide less shielding than aluminum. Hence, the need to avoid digital upsets of electronic systems is of interest. The level of penetration is dependent, among others, on the structure of the aircraft, the size and material of the windshield, the thickness, shape and type of material of the aircraft fuselage, and the type of communication systems installed on the aircraft. The field penetration level also depends on the type of electromagnetic threat striking the aircraft.