Summary
The FAA is revising an earlier NPRM for an airworthiness directive (AD) that applies to all Bombardier Model DHC-7 airplanes. The original NPRM would have required implementing a corrosion prevention and control program (CPCP) either by accomplishing specific tasks or by revising the maintenance inspection program to include a CPCP. The original NPRM resulted from a determination that, as airplanes age, they are more likely to exhibit indications of corrosion. This action revises the original NPRM by clarifying certain compliance aspects of the proposed AD that were not adequately defined in the original NPRM. We are proposing this supplemental NPRM to prevent structural failure of the airplane due to corrosion.