Summary
The FAA is revising an earlier proposed airworthiness directive (AD) for all McDonnell Douglas Model 717-200 airplanes. The original NPRM would have required inspecting the power conversion distribution unit (PCDU) to determine its part number, and modifying certain PCDUs. The original NPRM was prompted by 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. This action revises the original NPRM by reidentifying the part number reference for the proposed corrective action. We are proposing this supplemental NPRM 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.