On take-off the left engine exhaust gas temperature exceeded the maximum limit. The power was subsequently reduced to idle, and the aircraft was manoeuvred for a return to Melbourne. During the manoeuvring the turbine vibration increased and when upper limits were exceeded the engine was shut down. The aircraft landed with the airport emergency services on standby.
The high engine exhaust gas temperature reading was found to be a false indication which was traced to a high resistance within the exhaust gas harness assembly probably caused by moisture ingress in connectors. The high vibration reading had been investigated without determining the cause. The engine's vibration was being monitored by the operator who advised that since this incident the engine vibration readings have returned to normal.