Summary
This document proposes to revise an earlier proposed airworthiness directive (AD) that would apply to certain Rockwell Collins, Inc. (Rockwell) ADC-85, ADC-85A, ADC-850C, and ADC-850F air data computers that are installed on airplanes. The earlier NPRM would have required you to replace any affected air data computer (ADC) with one that has a reprogrammed and tested central processing unit (CPU) circuit card and circuit card assemblies. The earlier NPRM resulted from a flight test that showed that these ADCs could display an unwarranted ADC flag in response to the airplane's "Normal/Alternate Air" static source selection capability. Revised service information revealed the need to change the applicability of the affected ADC units that are installed on airplanes. In addition, evaluation of the public comments on the NPRM reveals the need to change the number and models of airplanes that could have the affected ADC units installed. Since these actions impose an additional burden over that proposed in the NPRM, we are reopening the comment period to allow the public the chance to comment on these additional actions.