Special Conditions: Avidyne Corporation, Textron Aviation Inc. Model 550, 560, and 560XL Airplanes; Electronic-System Security Protection From Unauthorized External Access

These special conditions are issued for Textron Aviation Inc. (Textron) Model 550, 560, and 560XL airplanes. These airplanes, as modified by Avidyne Corporation, will have a novel or unusual design feature when compared to the state of technology envisioned in the airworthiness standards for transport category airplanes. This design feature is Avidyne Corporation avionics that allow external connection to previously isolated data networks, which are connected to systems that perform functions required for the safe operation of the airplane. This feature creates a potential for unauthorized persons to access the aircraft-control domain and airline information-services domain, and presents security vulnerabilities related to the introduction of computer viruses and worms, user errors, and intentional sabotage of airplane electronic assets (networks, systems, and databases). The applicable airworthiness regulations do not contain adequate or appropriate safety standards for this design feature. 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.