Airworthiness Directives; Bombardier Model DHC-7 Series Airplanes

This amendment adopts a new airworthiness directive (AD), applicable to all Bombardier Model DHC-7 series airplanes, that requires removal of all attachment bolts and pre-load indicating (PLI) washers of the wing-to-fuselage attachment fittings; a one-time visual inspection to detect corrosion of each attachment bolt; and installation of new attachment bolts and PLI washers of the wing-to- fuselage attachment fittings. This amendment is prompted by issuance of mandatory continuing airworthiness information by a foreign civil airworthiness authority. The actions specified by this AD are intended to prevent failure of the attachment bolts of the wing-to-fuselage attachment fittings due to stress corrosion cracking, which could result in reduced structural integrity of the airplane.