Special Conditions: Learjet Model 24/25 Series Airplanes; High Intensity Radiated Fields (HIRF)

These special conditions are issued for the Learjet Model 24/ 25 Series airplanes, modified by Avcon Industries, 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 dual Innovative Solutions and Support, Inc., Air Data Display Units, and a single Innovative Solutions and Support, Inc., Analog Interface Unit that performs 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.