Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Saab Model SAAB 2000 series airplanes. This proposal would require replacing the radio tuning units (RTU's) and associated components with new, improved parts. This proposal is prompted by issuance of mandatory continuing airworthiness information by a foreign civil airworthiness authority. The actions specified by the proposed AD are intended to prevent NAV/ COM radios from simultaneously changing tuned frequencies and transponder codes due to a black screen failure or ``blanking'' of an RTU, which could result in loss of communications capability and air traffic control data.