Notice published: 19 September 2018
Discontinuation notice
Section 21 (2) of the Transport Safety Investigation Act 2003 (TSI Act) empowers the Australian Transport Safety Bureau (ATSB) to discontinue an investigation into a transport safety matter at any time. Section 21 (3) of the TSI Act requires the ATSB to publish a statement setting out the reasons for discontinuing an investigation.
On 4 September 2018, the ATSB commenced an investigation into high engine vibrations involving Avro RJ100, VH-NJY, on a flight from Prominent Hill, South Australia, to Port Augusta, South Australia on 30 August 2018. The Bureau of Meteorology had issued a significant meteorological information (SIGMET) for severe turbulence and icing along the aircraft’s planned flight path. The flight crew were aware of this SIGMET and later recalled it to be consistent with the actual conditions encountered in flight.
When cruising at FL 250[1] in instrument meteorological conditions, an engine vibration caution was annunciated on the master warning panel (MWP). The flight crew identified the number 4 engine was indicating 1.8 units of vibration (more than the specified maximum of 1.2 units). About this time the flight crew observed ice build-up on the windscreen. They commenced the applicable checklist actions, and the fault message cleared before the checklist was completed.
The MWP then indicated a second engine vibration caution, and the crew identified that the number 2 engine was indicating 2.1 units of vibration. They performed the applicable checklist actions for the number 2 engine, and the fault annunciation cleared. The flight crew then descended the aircraft to FL 190, where the outside air temperature was higher, to prevent further icing. In consultation with the operator, the flight crew elected to divert to Adelaide rather than continue the flight to Port Augusta. No further excessive engine vibrations were encountered.
The ATSB obtained additional information from the flight crew that identified that the crew had selected the engine anti-ice system on prior to the occurrence. This and other airframe anti-ice systems were reported to be functioning normally. The ATSB also obtained data from the aircraft’s flight data recorder for the flight.
The ATSB reviewed the available information relating to this occurrence as well as information from its database associated with any similar previous occurrences involving the same aircraft type. Based on this review, the ATSB considered it was very unlikely that further investigation would identify any systemic safety issues. Consequently, the ATSB has discontinued this investigation.
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[1] Flight level: at altitudes above 10,000 ft in Australia, an aircraft’s height above mean sea level is referred to as a flight level (FL). FL 250 equates to 25,000 ft.