AD Calls for Replacement of Batch of Shadin ADCs

 - September 27, 2006, 4:41 AM

The FAA has issued an Airworthiness Directive that mandates replacement of certain Shadin ADC-2000 air-data computers (ADCs) installed in about 450 aircraft, including a handful of Citation 501s, King Airs and Conquests. Effective January 26, the AD 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. Air-data computers are permitted a maximum altitude error of 25 feet on the ground, but tests showed the affected Shadin units potentially could show erroneous deviations of 100 to 8,000 feet, according to the FAA. The AD calls for replacement of affected air-data computers with modified units. Shadin will reimburse owner-operators for the cost of a new ADC as well as for labor to remove and replace the ADC and shipping it back to the company’s facility in St. Louis Park, Minn.