AD FAA-2012-0037

We are adopting a new airworthiness directive (AD) for certain Bombardier, Inc. Model DHC-8-400, -401, and -402 airplanes. This AD requires an inspection of a certain alternating current (AC) power wire bundle for damage, and repair if necessary. Additionally, this AD requires segregating the wire bundle into two wire bundles and installing Teflon tubing. This AD was prompted by multiple reports of the loss of certain AC systems caused by a burnt AC power wire bundle. We are issuing this AD to prevent the loss of ice protection systems for the angle of attack vanes, pitot probes, engine inlets, and windshields, and consequent loss of or misleading airspeed indication and increased workload for the flight crew, which could lead to loss of control of the airplane.