Airworthiness Directives; McDonnell Douglas Model MD-90-30 Series Airplanes

This amendment supersedes an existing airworthiness directive (AD), applicable to certain McDonnell Douglas Model MD-90-30 series airplanes, that currently requires replacement of certain ground block screws with new screws; and retermination of the circuit ground wires of the electrical power control unit (EPCU) to separate grounding points. This amendment removes certain airplanes and adds certain other airplanes to the applicability of the existing AD. The actions specified in this AD are intended to prevent a loose electrical ground block of the circuit ground wires of the EPCU, which could result in complete loss of the primary electrical power of an airplane during flight.