Aviation safety investigations & reports

Engine failure and collision with water involving Garlick Helicopters UH-1H, VH-ONZ Ben Boyd Reservoir, New South Wales, on 9 January 2020

Investigation number:
AO-2020-003
Status: Completed
Investigation completed
Phase: Final report: Dissemination Read more information on this investigation phase

Final report

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What happened

On 9 January 2020, the pilot of a Garlick Helicopters UH-1H, registered VH-ONZ, was tasked at Moruya, New South Wales, to assist fire-ground crews with a bush-fire clean-up operation near the town of Eden. After arriving in the hover overhead the Ben Boyd Reservoir to uplift water, the helicopter’s engine failed, resulting in a rapid descent, and impact with the water followed by sinking and rollover. The pilot conducted an underwater escape and sustained a minor injury. The helicopter was substantially damaged and later recovered from the reservoir.

What the ATSB found

The helicopter’s engine intake and compressor section were found to be damaged on initial examination by the operator’s maintenance organisation and the engine was subsequently sent to Honeywell Engines in the United States for a teardown inspection and failure analysis. Honeywell found indications of a restriction of oil flow to the main bearings in the front section of the engine, which led to their failure. This resulted in contact between the power and compressor shafts, disconnection of rotational drive to the fuel pump and fuel control, and subsequent fuel starvation. As the oil passages for the front section of the engine passed their flow tests, the reason for the restriction could not be determined.

The pilot had completed helicopter underwater escape training about 8 months prior to the accident and credited this as a life-saving course. The training also included elements for emergency breathing systems (EBS), but the pilot did not conduct those elements as the equipment had not been introduced into the company’s operation. Survivability research reports have consistently found drowning to be the leading cause of fatalities in helicopter water impact and ditching accidents, and therefore, the ATSB concluded that an EBS would have reduced the risk of drowning.

What has been done as a result

Following the accident, the pilot acquired a compressed air EBS and intends to conduct the EBS elements of future helicopter underwater escape training courses. The operator reported they have started investigating how to implement EBS company-wide, and how to attach the units to their pilots without limiting their movement when conducting long-line operations.

Safety message

Although helicopter fire control operations are predominantly conducted overland, the requirement to uplift water results in repeated approaches and departures overwater. If a catastrophic failure occurs in this period of the operation, the helicopter may have insufficient energy to be manoeuvred clear of water to an emergency landing site. Where helicopter underwater escape training is required for an operation, there is a recognition that an emergency may result in the need for an underwater escape, in which case an EBS would also likely be beneficial.

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The occurrence

Context

Safety analysis

Findings

Safety action

Glossary

Sources and submissions

Update 2

Update published: 30 October 2020

The occurrence

On 9 January 2020, the pilot of a Garlick Helicopters UH-1H was conducting aerial fire control operations when the helicopter lost power and collided with water near Eden (Ben Boyd Reservoir), New South Wales. The helicopter rolled inverted in the water and the pilot egressed from the helicopter. The pilot had recently completed helicopter underwater escape training (HUET). The pilot received minor injuries and the helicopter was substantially damaged.

The helicopter was subsequently recovered from the reservoir and inspected by the operator’s maintenance organisation. A borescope inspection of the engine compressor section revealed a rotor blade failure in addition to other rotor blade and inlet guide vane damage (Figure 1).

Figure 1: Borescope image of damage to engine compressor section

Figure 1: Borescope image of damage to engine compressor section. 
Source: Fleet Helicopters, annotated by the ATSB

Source: Fleet Helicopters, annotated by the ATSB

Engine teardown

An engine teardown was conducted by the manufacturer on 13 and 14 October 2020 at their facility in the United States. In addition to the failed compressor rotor blade, they found blade-tip rubbing of all the axial compressor rotor blades and the centrifugal compressor as a result of contact with their respective shrouds. The forward compressor shaft bevel gear was unevenly worn and exhibited excessive heat. There was a failure of the no. 21 roller bearing, which supported the front of the power turbine shaft, and a failure of the no. 1 ball bearing, which supported the front of the rotating compressor assembly. Both bearing failures exhibited excessive heat and wear, such that they could no longer maintain the centreline of their respective rotating assemblies.

Further investigation

The engine manufacturer has submitted the failed components to their failure analysis group for a detailed metallurgical examination. In addition, they will flow test the bearing support assembly that was used to supply lubrication oil to the no. 21 bearing.

The ATSB will continue to liaise with the operator, their maintenance organisation, the engine manufacturer and the United States National Transportation Safety Board (NTSB).

_____________

The information contained in this update is released in accordance with section 25 of the Transport Safety Investigation Act 2003 and is derived from the initial investigation of the occurrence. Readers are cautioned that new evidence will become available as the investigation progresses that will enhance the ATSB's understanding of the accident as outlined in this update. As such, no analysis or findings are included.

Update 1

Update published: 3 April 2020

The occurrence

On 9 January 2020, the pilot of a Garlick Helicopters UH-1H was conducting aerial fire control operations when the helicopter lost power and collided with water near Eden (Ben Boyd Reservoir), New South Wales. The helicopter rolled inverted in the water and the pilot egressed from the helicopter. The pilot had recently completed helicopter underwater escape training (HUET). The pilot received minor injuries and the helicopter was substantially damaged.

The helicopter was subsequently recovered from the reservoir and inspected by the operator’s maintenance organisation. A borescope inspection of the engine compressor section revealed a rotor blade failure in addition to other rotor blade and inlet guide vane damage (Figure 1).

Figure 1: Borescope image of damage to engine compressor section

Figure 1: Borescope image of damage to engine compressor section.
Source: Fleet Helicopters, annotated by the ATSB

Source: Fleet Helicopters, annotated by the ATSB

Further investigation

The ATSB have interviewed the pilot and liaised with the operator, their maintenance organisation, the engine manufacturer and the United States National Transportation Safety Board (NTSB).

The engine is scheduled to be examined by the manufacturer in the United States under the supervision of the NTSB.

 

_____________

The information contained in this update is released in accordance with section 25 of the Transport Safety Investigation Act 2003 and is derived from the initial investigation of the occurrence. Readers are cautioned that new evidence will become available as the investigation progresses that will enhance the ATSB's understanding of the accident as outlined in this update. As such, no analysis or findings are included.

Initial summary

The ATSB is investigating the collision with water involving a Garlick Helicopters UH-1H helicopter, registered VH-ONZ, near Eden, New South Wales, on 9 January 2020.

While conducting aerial fire control operations, the helicopter was reported to have lost power and collided with water (Ben Boyd reservoir) resulting in substantial damage. The pilot received minor injuries.

As part of the investigation the ATSB will interview the pilot and review other available data.

A report will be released at the end of the investigation. Should a critical safety issue be identified during the course of the investigation, the ATSB will immediately notify relevant stakeholders so appropriate and timely safety action can be taken.

General details
Date: 09 January 2020   Investigation status: Completed  
Time: 1559 EDT   Investigation level: Defined - click for an explanation of investigation levels  
Location   (show map): Ben Boyd Reservoir, Boydtown (near Eden)   Investigation phase: Final report: Dissemination  
State: New South Wales   Occurrence type: Engine failure or malfunction  
Release date: 21 September 2021   Occurrence category: Accident  
Report status: Final   Highest injury level: Minor  

Aircraft details

Aircraft details
Aircraft manufacturer Garlick Helicopters Inc  
Aircraft model UH-1H  
Aircraft registration VH-ONZ  
Serial number 5229  
Operator Aerial Agriculture PTY LTD  
Type of operation Aerial Work  
Sector Helicopter  
Damage to aircraft Substantial  
Departure point Moruya, New South Wales  
Destination Moruya, New South Wales  
Last update 21 September 2021