AD Proposed for Challenger Air-driven Generator

The FAA is proposing an airworthiness directive for the Bombardier CL-600-2B19 (CRJ) air-driven generator (ADG). The document cites three occasions when the ADG failed to provide power during scheduled checks. In all three cases an investigation revealed the silver-plated copper wires within the ADG power feeder cables were damaged due to galvanic corrosion. The FAA determined the silver-plating is inadequate for the application. Damaged power feeder wires may cause the ADG to be unable to provide emergency electrical power. The FAA is taking comments through November 7.