Airworthiness Directives; NavWorx, Inc. Automatic Dependent Surveillance Broadcast Universal Access Transceiver Units

We propose to adopt a new airworthiness directive (AD) for NavWorx, Inc. (NavWorx) Automatic Dependent Surveillance Broadcast (ADS-B) Universal Access Transceiver Units (unit). This proposed AD would require removing the ADS-B unit and would prohibit installing the affected unit on any aircraft. This proposed AD is prompted by a design change for the unit to broadcast a Source Integrity Level (SIL) of 3 when the uncertified internal global positioning system (GPS) source necessitates a SIL of 0. The proposed actions are intended to prevent an ADS-B unit from communicating unreliable position information to Air Traffic Control (ATC) and nearby aircraft, resulting in a potential aircraft collision.