Summary
The FAA proposes to supersede Airworthiness Directive (AD) 2010-23-04, which applies to all De Havilland Aircraft of Canada Limited Model DHC-8-400 series airplanes. AD 2010-23-04 requires repetitive detailed inspections of the nacelle attachment fittings for cracks, a conductivity inspection of the nacelle attachment fittings, and replacement if necessary. Since AD 2010-23-04 was issued, the FAA has determined that it is necessary to do a replacement with new nacelle attachment fittings. This proposed AD would retain the requirements of AD 2010-23-04, remove a certain inspection requirement for certain airplanes, and add a new requirement to replace the rear spar fitting and nacelle attaching structure with a new nacelle attachment fitting. The FAA is proposing this AD to address the unsafe condition on these products.