Airworthiness Directives; McDonnell Douglas Model 717-200 Airplanes

The FAA is adopting a new airworthiness directive (AD) for all McDonnell Douglas Model 717-200 airplanes. This AD requires inspecting the power conversion distribution unit (PCDU) to determine its part number, and modifying certain PCDUs. This AD results from reports of failed PCDUs, the loss of an electrical bus, and the presence of a strong electrical burning odor in the flight deck and forward cabin. We are issuing this AD to prevent the loss of an electrical bus due to PCDU failure, resulting in the loss of all flight displays for an unacceptable time period, and consequent emergency landing.