Special Conditions: Cessna Model 501 and 551 Series Airplanes; High-Intensity Radiated Fields (HIRF)

These special conditions are issued for Cessna Aircraft Company Cessna Model 501 and 551 series airplanes modified by ElectroSonics. These modified airplanes will have a novel or unusual design feature when compared to the state of technology envisioned in the airworthiness standards for transport category airplanes. The modification incorporates the installation of dual air data display unit systems that perform critical functions. The applicable airworthiness regulations do not contain adequate or appropriate safety standards for the protection of these systems from the effects of high- intensity-radiated fields (HIRF). These special conditions contain the additional safety standards that the Administrator considers necessary to establish a level of safety equivalent to that established by the existing airworthiness standards.