Airworthiness Directives; The Boeing Company Airplanes

The FAA is adopting a new airworthiness directive (AD) for certain The Boeing Company Model 737-8 and Model 737-9 airplanes. This AD was prompted by a Boeing review of the standby power system control unit (SPCU) design where a single point of failure exists internal to the SPCU. This AD requires installing four diodes and changing wire bundles in the P5 panel, as well as performing installation and power tests and applicable on-condition actions. The FAA is issuing this AD to address the unsafe condition on these products.