Special Conditions: Learjet Model 35, 35A, 36, and 36A Series Airplanes; High Intensity Radiated Fields (HIRF)

These special conditions are issued for Learjet Model 35, 35A, 36, and 36A series airplanes modified by Flight Test Associates. 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 installation of a Honeywell Model BA-250 altimeter indicator and a Model AM-250 barometric 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.