AD FAA-2018-0409

We propose to supersede Airworthiness Directive (AD) 2017-16- 05, which applies to certain The Boeing Company Model 737-600, -700, - 700C, -800, -900, and -900ER series airplanes. AD 2017-16-05 requires a one-time detailed visual inspection for discrepancies in the Krueger flap bullnose attachment hardware, and related investigative and corrective actions if necessary. Since we issued AD 2017-16-05, we received a report of a missing no. 2 Krueger flap bullnose hinge bolt from an airplane that was not included in the applicability of AD 2017- 16-05. This proposed AD would add airplanes and an additional inspection to determine if any Krueger flap no. 1, 2, 3, or 4 has been replaced, and related investigative and corrective actions. Since this is a rotable parts issue, the applicability of this AD has been expanded beyond the airplanes listed in the related service bulletin to include all airplanes on which a Krueger flap bullnose may be installed. We are proposing this AD to address the unsafe condition on these products.