Special Conditions; Piper Cheyenne PA-31T, PA-31T1, and PA-31T2; Protection of Systems for High Intensity Radiated Fields (HIRF)

These special conditions are issued to Marinvent Corporation, 50 Rabastaliere East, Suite 23, St. Bruno, Quebec, Canada J3V2A5 for Federal Aviation Administration validation of a Canadian supplemental type certificate (STC) to install the Meggitt Magic Electronic Flight Instrument System (EFIS) and Air Data Attitude and Heading Reference System (ADAHRS) on the Piper Cheyenne model PA-31T, PA-31T1, and PA- 31T2 airplanes. These airplanes will have novel and unusual design features when compared to the state of technology envisaged in the applicable airworthiness standards. These novel and unusual design features include the installation of electronic flight instrument system (EFIS) displays and digital attitude sensing equipment 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.