Summary
This document proposes to revise an existing airworthiness directive (AD), applicable to certain de Havilland Model DHC-8-100, - 200, and -300 series airplanes, that currently requires modification of the attitude and heading reference systems (AHRS). That AD was prompted by a report of loss of power to both AHRS's during flight due to a faulty terminal block to which the signal ground for the AHRS's is connected. The actions specified by that AD are intended to prevent simultaneous power loss to both AHRS's, which could result in reduced controllability of the airplane. This action would reduce the applicability of the existing AD.