Special Conditions: Raytheon Model BH125 Series 400A and 600A Airplanes; High Intensity Radiated Fields (HIRF)

These special conditions are issued for Raytheon Model BH125 Series 400A and 600A airplanes. 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 modification incorporates the installation of dual Honeywell Model AM-250 digital altimeters. 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.