Summary
The FAA proposes to adopt a new airworthiness directive (AD) for certain The Boeing Company Model 737-8 and Model 737-9 airplanes. This proposed 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 proposed AD would require the installation of 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 proposing this AD to address the unsafe condition on these products.