Summary
We propose to adopt a new airworthiness directive (AD) for certain Bombardier, Inc. Model DHC-8-400 series airplanes. This proposed AD was prompted by reports of chafing of the fuel lines due to contact with the surrounding structures in the fuel tank. This proposed AD would require replacing and modifying fuel lines, revising the maintenance or inspection program, as applicable, to include critical design configuration control limitations (CDCCL) and airworthiness limitation (AWL) items, and, for certain airplanes removing certain clamps and mounting hardware. We are proposing this AD to prevent chafing of the fuel lines in the fuel tank, which could result in potential ignition sources in the fuel tank in the event of a lightning strike and consequent fire or explosion.