July 14, 2020 Airworthiness Directives; De Havilland Aircraft of Canada Limited (Type Certificate Previously Held by Bombardier, Inc.) Airplanes

The FAA is superseding Airworthiness Directive (AD) 2010-23- 04, which applied to all De Havilland Aircraft of Canada Limited Model DHC-8-400 series airplanes. AD 2010-23-04 required repetitive detailed inspections of the nacelle attachment fittings for cracks, a conductivity inspection of the nacelle attachment fittings, and replacement if necessary. This AD continues to require these inspections and replacement if necessary, removes a certain inspection requirement for certain airplanes, and adds a new requirement to replace the rear spar fitting and nacelle attaching structure with a new nacelle attachment fitting. This AD was prompted by a determination that it is necessary to do a replacement with new nacelle attachment fittings. The FAA is issuing this AD to address the unsafe condition on these products.