Summary
We propose to supersede Airworthiness Directive (AD) 2016-24- 03, which applies to certain Bombardier, Inc., Model DHC-8-400 series airplanes. AD 2016-24-03 requires repetitive detailed inspections of barrel nuts and cradles, a check of the bolt torque of the preload indicating (PLI) washers, and corrective actions if necessary. Since we issued AD 2016-24-03, the manufacturer has developed a modification that, when incorporated, terminates the repetitive inspections. This proposed AD would require modifying the airplane by installing a sealing disk to a certain location and replacing certain barrel nuts. We are proposing this AD to address the unsafe condition on these products.