Special Conditions: Modified Learjet Model 55, 55B and 55C Airplanes; High Intensity Radiated Fields (HIRF)

These special conditions are issued for the Learjet Models 55, 55B, and 55C airplanes modified by Duncan Aviation, Inc., of Lincoln, Nebraska. These models will be equipped with a Flight Visions Corporation, FV-2000 Head-Up Display System (HUD) that will perform critical functions. The applicable regulations do not contain adequate or appropriate safety standards for the protection of the HUD from the effects of high-intensity radiated fields (HIRF). These special conditions provide the additional safety standards that the Administrator considers necessary to ensure that the critical functions performed by this system are maintained when the airplane is exposed to HIRF.