Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Dornier Model 328-100 series airplanes. This proposal would require replacement of a bus power control unit (BPCU) and two generator control units (GCU) with new improved units. This proposal is prompted by results of the manufacturer's re-certification and laboratory testing of a BPCU, which revealed abnormal functions of the BPCU and the GCU. The actions specified by the proposed AD are intended to prevent such abnormal functions, which could result in electrical short circuits in the electrical power distribution systems and a subsequent fire.