An airworthiness directive published last month requiring replacement of Shadin ADC-2000 computers only affects aircraft owners with “Quick Start” models or those who participated in Alaska’s Capstone project. The AD, not effective until January 23, was prompted by the discovery of potential errors in some units that could cause them to display incorrect altitude information on their Chelton FlightLogic EFIS displays. Following a product recall this summer, Shadin Avionics said it has replaced or repaired the majority of the 350 potentially affected units sold. The company said it will reimburse up to two hours of labor, as well as provide a loaner unit when needed. In some cases, Shadin will directly exchange the affected unit with an already updated/modified one.