AD FAA-2019-0409

The FAA is adopting an airworthiness directive (AD) for certain The Boeing Company Model 737-700C, -800, and -900ER series airplanes. This AD requires a maintenance records check to determine if any main slat track assembly has been removed, an inspection of the main slat track assemblies for a suspect lot number or a lot number that cannot be determined, and applicable on-condition actions. This AD was prompted by a report that certain main slat track assemblies were manufactured incorrectly and are affected by hydrogen embrittlement. The FAA is issuing this AD to address the unsafe condition on these products.