Investigation number
AO-2009-078
Occurrence date
Location
296 km NE of Perth Airport
State
Western Australia
Report release date
Report status
Final
Investigation level
Short
Investigation type
Occurrence Investigation
Investigation status
Completed
Aviation occurrence category
Diversion/return
Occurrence class
Serious Incident
Highest injury level
None

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.

Aircraft Details
Manufacturer
De Havilland Canada
Model
DHC-8
Registration
VH-XFU
Serial number
151
Operation type
Charter
Sector
Turboprop
Departure point
Perth, WA
Destination
Darlot, WA
Damage
Nil