Summary
We are revising an earlier supplemental NPRM for the products listed above. This action revises the earlier supplemental NPRM by expanding the scope. This proposed AD results from mandatory continuing airworthiness information (MCAI) originated by an aviation authority of another country to identify and correct an unsafe condition on an aviation product. The MCAI describes the unsafe condition as:
It has been found that some "caution" messages issued by the Flight Guidance Control System (FGCS) are not displayed on aircraft equipped with [certain] EPIC software load[s] * * *. Therefore, following a possible failure on one FGCS channel during a given flight, such a failure condition will remain undetected * * *. If another failure occurs on the second FGCS channel, the result may be a hardover command by the autopilot.
An unexpected hardover command may cause a sudden roll, pitch, or yaw movement, which could result in reduced controllability of the airplane. The proposed AD would require actions that are intended to address the unsafe condition described in the MCAI.