Aviation safety investigations & reports

Engine failure involving an Airbus Helicopters AS355F-1, VH-SEV, Bankstown Airport, New South Wales, on 12 March 2018

Investigation number:
AO-2018-021
Status: Completed
Investigation completed
Phase: Final report: Dissemination Read more information on this investigation phase

Final Report

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What happened

At about 0828 Eastern Daylight-saving Time (EDT), on 12 March 2018, an Airbus Helicopters AS355F-1 helicopter, VH-SEV, operated by Rotor Head, air taxied from the hangar to the maintenance facility at Bankstown Aerodrome, New South Wales with the pilot and one passenger on board.

After about 5 minutes in flight, the pilot commenced the landing. As the skids touched the ground, the pilot observed the right-hand engine chip light illuminate and smoke coming from the right-hand side of the aircraft. The pilot immediately shut down the right-hand engine. Mechanics from a nearby workshop ran out and extinguished the engine fire.

The aircraft sustained significant damage to the engine and minor heat damage to the surrounding structure.

What the ATSB found

A single third-stage turbine wheel blade failed due to fatigue cracking, resulting in secondary damage to the engine and total engine failure. The rapid fatigue crack progression was probably caused by a momentary dwell in the speed avoidance range.

A number of fatigue cracks were present but not detected during the last inspection of the third-stage wheel. The size and nature of the cracks meant there was a low probability of detection using the method specified.

What's been done as a result

Rolls-Royce are in the process of redesigning the third-stage turbine wheel to improve its tolerance to fatigue cracking and operation at responsive wheel modes.

Safety message

Any operator, irrespective of their level of experience, can find themselves confronted with an unexpected failure. Therefore, it is important for operators to monitor aircraft performance parameters continuously for abnormal indications. Acting quickly to shut down malfunctioning hardware and following failure management procedures will ensure the best possible safety outcome, as demonstrated by the pilot in this occurrence.

During this investigation, Rolls-Royce advised the ATSB of a few key points regarding the operation of the Rolls-Royce 250 enhanced power turbine engine:

  • A dwell in the order of a few seconds can be enough to initiate damage and propagate a crack to failure.
  • The best way for an operator to monitor the transition through the speed avoidance range is to watch the needle on the N2 tachometer. If the needle stops, that constitutes a dwell.
  • If an operator recognises or suspects an inadvertent dwell in the speed avoidance range, contact Rolls-Royce for advice.

Third-stage turbine wheel removed from VH-SEV showing damage

Third-stage turbine wheel removed from VH-SEV showing damage
Source:  ATSB

Source: ATSB

Download final report
[Download  PDF: 934KB]
 
 
 

The occurrence

Context

Safety analysis

Findings

Safety issues and actions

Sources and submissions

Appendices

General details
Date: 12 March 2018   Investigation status: Completed  
Time: 0828 AEDT   Investigation level: Defined - click for an explanation of investigation levels  
Location   (show map): Bankstown Airport   Investigation phase: Final report: Dissemination  
State: New South Wales   Occurrence type: Engine failure or malfunction  
Release date: 12 March 2020   Occurrence category: Serious Incident  
Report status: Final   Highest injury level: None  

Aircraft details

Aircraft details
Aircraft manufacturer Airbus Helicopters  
Aircraft model AS355F-1  
Aircraft registration VH-SEV  
Serial number 5272  
Operator Rotor Head  
Type of operation Aerial Work  
Sector Helicopter  
Damage to aircraft Minor  
Departure point Bankstown, New South Wales  
Destination Bankstown, New South Wales  
Last update 20 July 2020