On 15 December 2009, a De Havilland Canada DHC-8-102 aircraft, registered VH-XFU, departed Perth, Western Australia (WA) on a charter passenger service to Darlot, WA. While cruising at flight level (FL) 230, the aircraft sustained multiple system failures, followed by a depressurisation. The crew actioned the aircraft depressurisation checklist and commenced an emergency descent. During the descent, a number of system cautions and warnings illuminated. The crew elected to return to Perth and a descent to 8,000 ft was made. Shortly after, the majority of the aircraft's systems returned to normal.
A subsequent engineering investigation was unable to replicate the system faults. However, it appeared that the number 1 direct current (DC) generator output was spiking, causing power to the left DC buses to be repeatedly switched between the number 1 transformer rectifier unit and the left DC generator. This repeated power switching resulted in some of the aircraft's systems behaving erratically.
As a precaution, the number 1 generator control unit, number 1 DC generator and left bus tie relay were replaced.