Airworthiness Directives; Bombardier, Inc. Airplanes

We are adopting a new airworthiness directive (AD) for certain Bombardier, Inc. Model DHC-8-400 series airplanes. This AD was prompted by reports of cracking of certain fuel access panels of the outer wing. This AD requires an external inspection, and if necessary an internal inspection, to determine if certain fuel access panels are installed, and replacement if necessary; optional repetitive inspections for cracking of the fuel access panels, and replacement if necessary, would defer the internal inspection; and eventual replacement of affected fuel access panels with new panels. We are issuing this AD to prevent cracking of fuel access panels, which could result in arcing and ignition of fuel vapor in the outer wing fuel tank during a lightning strike.