Special Conditions: Boeing 747-200/-300 Series Airplanes; High-Intensity Radiated Fields (HIRF)

These special conditions are issued for Boeing Model 747-200/-300 series airplanes modified by Hollingsead International, Inc. These modified airplanes will have a novel or unusual design feature when compared to the state of technology envisioned in the airworthiness standards for transport category airplanes. The modification incorporates the installation of new Liquid Crystal Flight Instruments as Attitude Directional Indicators (ADI), the Horizontal Situation Indicators (HSI) and Engine Display Interface System (EDIS). The liquid crystal flight instruments will utilize electrical and electronic systems that perform 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 tothat established by the existing airworthiness standards.