Special Conditions: Raytheon Aircraft Company Model HS.125 Series 700A Airplanes; High Intensity Radiated Fields (HIRF)

These special conditions are issued for Raytheon Aircraft Company Model HS.125 Series 700A airplanes modified by Duncan Aviation. These 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 modifications, under three separate supplemental type certificate (STC) projects, incorporate the installation of a Collins FDS2000 Electronic Flight Instrument System (EFIS), a dual Collins AHS-3000A Attitude Heading Reference System (AHARS), and a dual IS&S Air Data System. 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.