Airworthiness Directives; The Boeing Company Airplanes

The FAA is adopting a new airworthiness directive (AD) for certain The Boeing Company Model 737-700 series airplanes. This AD requires repetitive testing to verify correct operation of the smoke clearance mode of the equipment cooling system and low pressure environmental control system, and corrective actions if necessary. This AD also requires installing new relays and changing the wiring to the environmental control system, among other actions. This AD was prompted by a determination that a repetitive test is needed to assess the components on airplanes equipped with a certain air distribution system configuration. The FAA is issuing this AD to address the unsafe condition on these products.