Airworthiness Directives; Bombardier Model DHC-8-400 Series Airplanes

The FAA is adopting a new airworthiness directive (AD) for certain Bombardier Model DHC-8-400 series airplanes. This AD requires revising the Airworthiness Limitations Items (ALI) of the maintenance requirements manual to require additional inspection requirements of the maintenance requirements manual for certain principal structural elements (PSEs) related to fuselage cutouts and to reduce an inspection threshold for an existing ALI task on the aft entry door. This AD results from data obtained from the manufacturer's fatigue testing. We are issuing this AD to detect and correct fatigue cracking of certain PSEs, which could result in reduced structural integrity of the airplane.