Airworthiness Directives; The Boeing Company Airplanes

The FAA is adopting a new airworthiness directive (AD) for all The Boeing Company Model 707, 717, and 727 airplanes; Model DC-8, DC-9, and DC-10 airplanes; Model MD-10 and MD-11 airplanes; Model DC-9-81 (MD-81), DC-9-82 (MD-82), DC-9-83 (MD-83), DC-9-87 (MD-87), and MD-88 (collectively described, in the preamble of this AD, as MD-80) airplanes; and Model MD-90-30 airplanes. This AD was prompted by a determination that radio altimeters cannot be relied on to perform their intended function if they experience interference from wireless broadband operations in the 3.7-3.98 GHz frequency band (5G C-Band), and a recent determination that during approach, landings, and go- arounds, as a result of this interference, certain airplane systems may not properly function, resulting in increased flightcrew workload while on approach with the flight director, autothrottle, or autopilot engaged. This AD requires revising the limitations and operating procedures sections of the existing airplane flight manual (AFM) to incorporate specific operating procedures for, depending on the airplane model, instrument landing system (ILS) approaches, non- precision approaches, ground spoiler deployment, and go-around and missed approaches, when in the presence of 5G C-Band interference as identified by Notices to Air Missions (NOTAMs). The FAA is issuing this AD to address the unsafe condition on these products.