Summary
The FAA proposes to adopt a new airworthiness directive (AD) for certain Bombardier Model DHC-8-400 series airplanes. This proposed AD would require replacing all domed anchor nuts at all attachment locations of the upper fuel access panels of the center wing in the wet bay location with new nuts. This proposed AD results from reported cases of corroded dome anchor nuts at the attachment locations of the upper surface of the fuel access panel of the center wing. We are proposing this AD to prevent corrosion or perforation of domed anchor nuts, which could result in arcing and ignition of fuel vapor in the center wing fuel tank during a lightning strike and consequent explosion of the fuel tank.