Airworthiness Directives; The Boeing Company Airplanes

The FAA is superseding Airworthiness Directive (AD) 2012-21- 08, which applied to certain The Boeing Company Model 737-600, -700, - 700C, -800, and -900 series airplanes. AD 2012-21-08 required inspecting for part numbers of the operational program software (OPS) of the flight control computers (FCCs) and installing and testing an updated version of the FCC OPS. This AD was prompted by reports that during autopilot coupled instrument landing system (ILS) approaches, the airplane did not capture or track the glideslope correctly. This AD retains the requirement to inspect for part numbers of the OPS of the FCCs, and adds a new requirement to update the version of the FCC OPS if necessary. This AD also expands the applicability to include The Boeing Company Model 737-900ER series airplanes. The FAA is issuing this AD to address the unsafe condition on these products.