Special Conditions: Cessna Models 500, 550 and S550 Airplanes; High Intensity Radiated Fields (HIRF)

These special conditions are issued for Cessna Models 500, 550 and S550 airplanes modified by Shadin Company, Inc. These modified airplanes will have novel and unusual design features when compared to the state of technology envisioned in the airworthiness standards for transport category airplanes. The modification incorporates the installation of the Shadin Company dual ADC-6000 Air Data Computer (ADC) which will allow for the removal of the existing encoding altimeters, air data computer, and pneumatic altimeter. 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 provided by the existing airworthiness standards.