Special Conditions; Twin Commander Aircraft Models 690C, 690D, 695, 695A, and 695B; Protection of Systems for High Intensity Radiated Fields (HIRF)

These special conditions are issued to Twin Commander Aircraft LLC. 19010 59th DR. NE. Arlington, WA. 98223 for a Supplemental Type Certificate for the Twin Commander Aircraft Models 690C, 690D, 695, 695A, and 695B. These airplanes will have novel and unusual design features when compared to the state of technology envisaged in the applicable airworthiness standards. The novel and unusual design features include the installation of dual Innovative Solutions & Support (IS&S) Air Data Display Units (ADDU) for which the applicable regulations do not contain adequate or appropriate airworthiness 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 the airworthiness standards applicable to these airplanes.