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BUS
Safety Investigation Report
Engine Bay Fire Tongarra, NSW 3 September 2018
BUS SAFETY INVESTIGATION REPORT
Engine Bay Fire Tongarra, NSW 3 September 2018
Released under the provisions of Section 45C (2) of the Transport Administration Act 1988 and Section 46BBA (1) of the Passenger Transport Act 1990 OTSI File 04804 Cover photo source: Premier Motor Service
Published by: The Office of Transport Safety Investigations
Postal address: PO Box A2616, Sydney South, NSW 1235
Office location: Level 17, 201 Elizabeth Street, Sydney NSW 2000
Telephone: 02 9322 9200
Accident and incident notification: 1800 677 766
Email: [email protected]
Website: www.otsi.nsw.gov.au
This Report is Copyright©. In the interests of enhancing the value of the information
contained in this Report, its contents may be copied, downloaded, displayed, printed,
reproduced and distributed, but only in unaltered form (and retaining this notice).
However, copyright in the material contained in this Report which has been obtained
by the Office of Transport Safety Investigations from other agencies, private
individuals or organisations, belongs to those agencies, individuals or organisations.
Where the use of their material is sought, a direct approach will need to be made to
the owning agencies, individuals or organisations.
Subject to the provisions of the Copyright Act 1968, no other use, may be made of the
material in this Report unless permission of the Office of Transport Safety
Investigations has been obtained.
THE OFFICE OF TRANSPORT SAFETY INVESTIGATIONS
OTSI is an independent NSW authority which contributes to the safe operation of bus,
ferry and rail passenger and rail freight services in NSW by investigating safety
incidents and accidents and transport safety risks, identifying system-wide safety
issues and sharing lessons with transport operators, regulators and other
stakeholders.
OTSI is empowered under the Transport Administration Act 1988 to investigate rail,
bus, and ferry accidents and incidents in accordance with the provisions of the
Passenger Transport Act 1990 and Marine Safety Act 1998. It also conducts rail
investigations on behalf of the Australian Transport Safety Bureau under the Transport
Safety Investigation Act 2003 (Cth).
OTSI investigations are independent of regulatory, operator or other external entities.
OTSI investigates using a ‘no-blame’ approach to understand why an occurrence took
place and to identify safety factors that are associated with an accident and incident,
to make recommendations or highlight actions that transport operators, regulators and
government can take to prevent recurrence and improve safety.
Evidence obtained through an OTSI investigation cannot be used in any subsequent
criminal or disciplinary action. However, a regulator can undertake its own
investigation into an incident OTSI has investigated and coronial inquiries can obtain
access to OTSI information.
OTSI does not investigate all transport safety incidents and accidents but focuses its
resources on those investigations considered most likely to enhance bus, ferry or rail
safety. Many accidents result from individual human or technical errors which do not
involve safety systems so investigating these in detail may not be justified. In such
cases, OTSI will not generally attend the scene, conduct an in-depth investigation or
produce an extensive report.
OTSI may request additional information from operators or review their investigation
reports which may lead to a number of actions, such as the release of a Safety
Advisory or Alert to raise industry awareness of safety issues and action.
OTSI investigators normally seek to obtain information cooperatively when conducting
an investigation. However, where it is necessary to do so, OTSI investigators may
exercise statutory powers to conduct interviews, enter premises and examine and
retain physical and documentary evidence.
Publication of the investigation report
OTSI produces a written report on every investigation for the Minister for Transport
and Roads, as required under section 46BBA of the Passenger Transport Act 1990.
Investigation reports strive to reflect OTSI’s balanced approach to the investigation,
explaining what happened and why in a fair and unbiased manner. All DIPs will be
given the opportunity to comment on the draft investigation report.
The final investigation report will be provided to the Minister for tabling in both Houses
of the NSW Parliament in accordance with section 46D of the Passenger Transport
Act 1990. The Minister is required to table the report within seven days of receiving it.
Following tabling, the report is published on the OTSI website – www.otsi.nsw.gov.au
– and information on the safety lessons promoted to relevant stakeholders.
OTSI Bus Safety Investigation
Bus fire, Tongarra, 3 September 2018 i
CONTENTS
TABLE OF FIGURES ii
EXECUTIVE SUMMARY iii
PART 1 FACTUAL INFORMATION 1
The occurrence 1
Location 2
Environmental information 2
Operator information 3
Bus information 3
Related occurrences 3
PART 2 ANALYSIS 4
Introduction 4
Damage 4
Initiation and spread of fire 6
Evacuation of bus 12
Fire extinguisher and alarms 12
PART 3 FINDINGS 13
Contributory factors 13
Other findings 13
PART 4 RECOMMENDATIONS 14
Bus operators 14
PART 5 APPENDICES 15
Appendix 1: Sources and References 15
OTSI Bus Safety Investigation
Bus fire, Tongarra, 3 September 2018 ii
TABLE OF FIGURES
Figure 1: Location map 1
Figure 2: Engine bay of 7257 MO 5
Figure 3: Engine bay of same model bus, 7294 MO 5
Figure 4: Fuel line misalignment 1 7
Figure 5: Fuel line misalignment 2 8
Figure 6: Fuel line fittings 8
Figure 7: OEM body build instruction (BBI) 9
Figure 8: Typical barb type fuel banjo fitting, bolt and sealing washers 9
Figure 9: Diesel fuel residue from ruptured fuel line 10
Figure 10: Rotational heat patterns 10
Figure 11: Location of electrical short circuit 11
Figure 12: Testing continuity of A/C system main fuse and battery main switch 11
OTSI Bus Safety Investigation
Bus fire, Tongarra, 3 September 2018 iii
EXECUTIVE SUMMARY
On Monday 3 September 2018, the driver of a Premier Motor Service bus was
travelling on the Illawarra Highway near Tongarra when they noticed the engine bay
fire suppression system alarm had activated. The driver stopped the bus and
inspected the cause of the alarm and found smoke emitting from the engine bay area.
The driver evacuated the sole passenger from the bus then attempted to extinguish
the fire, however the fire continued to burn. Fire and Rescue NSW attended the scene
and extinguished the fire, however the bus was severely damaged by the fire and was
later determined a total loss.
There were no reported injuries to any person.
The investigation found that the fire was likely initiated from a fuel leak from a damaged
fuel line. Once the fire had begun, it was perpetuated by a continual supply of diesel
fuel and other combustible material in the engine bay.
The investigation also found that the power from the batteries to the engine bay was
still live, despite the driver turning the ignition off. This meant the fire could reignite
following the discharge of the fire suppression system.
OTSI recommended that the bus operator review maintenance and inspection
systems to ensure the integrity of fuel system components.
Full details of the Findings and Recommendations of this bus safety investigation are
contained in Parts 3 and 4 respectively.
OTSI Bus Safety Investigation
Bus engine bay fire, Tongarra, 3 September 2018 1
PART 1 FACTUAL INFORMATION
The occurrence
1.1 At approximately 15101 on Monday 3 September 2018, while travelling along
the Illawarra Highway at Tongarra, south of Wollongong (Figure 1), the driver
of a Premier Motor Service (Premier) bus 7257 MO was alerted to a possible
fire by the engine bay fire suppression system (EBFSS) alarm. The alarm also
indicated that the EBFSS had discharged.
Source: Google, annotated by OTSI
Figure 1: Location map
1.2 The driver then located a safe area and brought the bus to a stop and secured
the vehicle. The driver alighted from the bus to investigate the cause of the
alarm and discovered smoke emitting from the engine bay area. The driver
then returned to the front door and instructed the sole passenger on board to
evacuate.
1 Times in this report are in 24-hour clock format in Australian Eastern Standard Time (AEST): Coordinated Universal Time (UTC) + 10 hours
OTSI Bus Safety Investigation
Bus engine bay fire, Tongarra, 3 September 2018 2
1.3 Review of the vehicle’s CCTV showed a member of the public offered
assistance and called emergency services while the driver retrieved the fire
extinguisher from the bus.
1.4 The driver attempted to extinguish the fire, however the fire continued to burn.
The driver then contacted the Premier control room and notified it of the
situation.
1.5 The CCTV footage showed the intensity of the fire increasing, up until the
recording ceased at approximately 1514.
1.6 Fire and Rescue NSW attended the scene and extinguished the fire, however
the bus was severely damaged by the fire and was later determined a total
loss.
1.7 A Fire and Rescue NSW Hazmat team were also deployed to decontaminate
the road surface for diesel fuel residue adjacent to and leading up to the
incident location.
Location
1.8 The incident occurred in the rural locality of Tongarra, located in the
Shellharbour Local Government Area (LGA) approximately 113 km southwest
of Sydney’s CBD. At the time of the incident, the bus was travelling westbound
on the Illawarra Highway, eventually stopping 250 m from the intersection with
Tongarra Mine Road.
Environmental information
1.9 At 1500, the Bureau of Meteorology recorded a temperature of 12.2˚ C with a
south by south-westerly wind of 11 km/h at Albion Park weather station, which
is approximately 13 km from the incident site.
1.10 Apart from the likely effect of wind on the promotion of the fire and the
dispersal of smoke, it was determined that the environmental conditions
played no part in the incident.
OTSI Bus Safety Investigation
Bus engine bay fire, Tongarra, 3 September 2018 3
Operator information
1.11 Premier’s operations and maintenance are based in the Wollongong suburb
of Unanderra. The company provides services under Transport for NSW’s
Outer Sydney Metropolitan Bus Service Contracts Region 9 (OSMBSC009)
as well as various services including charter, tourist and educational transport
services. Premier has a mixed fleet of approximately 196 buses and coaches.
Vehicle 7257 MO was operated and maintained from a satellite depot at
Shellharbour.
Bus information
1.12 The bus was a diesel fuelled 2013 model Iveco Metro Delta Euro 5. The body
was manufactured by Volgren Australia Pty Ltd and was registered in NSW
as 7257 MO. Maintenance records showed that the bus had travelled less
than 150,000 km and had a routine 12 monthly service on 29 August 2018.
There were no defects detected relevant to this incident.
1.13 A Heavy Vehicle Inspection Scheme (HVIS) inspection was conducted by the
Roads and Maritime Services2 (RMS) on 17 August 2018. No defects were
recorded as a result of this inspection.
1.14 The bus was authorised to carry 58 seated passengers. At the time of the
incident there was one passenger on board.
1.15 There were no previous reported fire incidents for this bus.
Related occurrences
1.16 During the course of this investigation, OTSI investigators deployed to another
fire involving a coach with a similar model engine and fuel arrangement as
fitted to 7257 MO. The incident occurred in January 2019 at Shoal Bay, NSW.
In this instance, it was found that a fuel leak had propagated from a fuel fitting
fitted to the secondary fuel filter as that observed on 7257 MO. The
2 On 21 November 2019, NSW Parliament passed legislation that enabled the full integration of Transport for New South Wales (TfNSW) and RMS into one organisation. Effective as at 1 December 2019, RMS was dissolved and its functions became the functions of TfNSW.
OTSI Bus Safety Investigation
Bus engine bay fire, Tongarra, 3 September 2018 4
circumstances of the initiation, propagation and damage caused by the fire
were near identical to that observed in this investigation.
PART 2 ANALYSIS
Introduction
2.1 OTSI analysed several sources of information relating to the incident in parallel
with an inspection of the bus following the event.
2.2 These sources included an internal investigation report and service history of
the bus submitted by Premier, HVIS inspection records, the National Heavy
Vehicle Inspection Standards (NHVIS), CCTV footage from the bus and the
driver’s version of events.
2.3 The investigation focused primarily on the factors that contributed to the
initiation of the fire, evacuation of passengers, maintenance of the vehicle and
driver training.
Damage
2.4 The majority of the fire damage was confined to components within the rear of
the engine bay, aluminium bulkhead and corner panels, rear engine bay access
panels and fibreglass exterior rear panels (see Figures 2 and 3).
2.5 The passenger saloon area was severely heat affected with some plastic and
foam components consumed by fire.
2.6 Heat damage was also evident throughout the engine bay area and battery
compartment.
2.7 The engine cooling system heat exchanger (radiator) assembly was mostly
unaffected by the fire.
OTSI Bus Safety Investigation
Bus engine bay fire, Tongarra, 3 September 2018 5
Source: OTSI
Figure 2: Engine bay of 7257 MO
Source: OTSI
Figure 3: Engine bay of same model bus, 7294 MO
OTSI Bus Safety Investigation
Bus engine bay fire, Tongarra, 3 September 2018 6
Initiation and spread of fire
2.8 Examination of the diesel fuel system indicated that a fuel leak likely initiated at
a pinch point within the fuel supply line (see Figures 4, 5, 6, 7 and 8). Due to its
proximity to the engine cooling fan assembly, it is likely that fuel leaking from
this fitting was spread throughout the engine bay by the air flow from the cooling
system fan. When the vehicle was inspected following the fire, diesel fuel
residue was evident on the pressurised fuel filter assembly and cooling fan
support frame (see Figure 9).
2.9 It is likely that fuel from this point came into contact with hot engine exhaust
components, causing the fuel to vaporise. Once vaporised, the fuel likely
contacted an ignition source such as an electrical spark generated by the
alternator slip ring brushes.
2.10 As the fuel filter is located on the pressure side of the fuel system, fuel would
continue to flow unimpeded without adversely affecting the performance of the
vehicle. Statements made by the driver of the bus and CCTV recordings
confirmed that the vehicle operated without issue up to and including the point
where the driver shut it down following activation of the EBFSS.
2.11 Fire damage was observed on several drive pulleys and the cooling fan
assembly, which likely indicated that the fire was active while the engine was in
operation (see Figure 10). Similarly, the lack of heat damage to the aluminium
cooling system heat exchanger core, likely indicates that the cooling fan was
rotating during the commencement of the fire event, drawing cooling air into the
engine compartment.
2.12 Inspection of the vehicle revealed that within the area adjacent to the engine
cooling fan assembly and panels directly adjacent to this area appeared to be
more heat affected than the rest of the engine bay area.
2.13 The main battery positive and air-conditioning (A/C) cables exhibited evidence
of electrical short circuiting3. When tested for continuity4, the main A/C feed
3 ‘A short circuit is when there is direct contact between a current carrying conductor and another conductor.’ - Kirk’s fire investigation (2012) DeHaan. J.D.; Icove.D.J. 7th Ed. p.79. 4 Continuity testing is the act of testing the resistance between two points in an electrical circuit or component. If there is very low resistance (less than a few ohms), the two points are connected electrically and is commonly known as a closed circuit.
OTSI Bus Safety Investigation
Bus engine bay fire, Tongarra, 3 September 2018 7
circuit fuse indicated near to zero resistance which indicates electrical current
was still being supplied to the short circuit area via the main fuse (see Figure
12).
2.14 The main battery isolation switch was unable to be operated at the time of the
fire due to its proximity to the fire activity within the engine bay area (see Figure
12).
2.15 It is likely that the continuing flow of energy from the main A/C feed to the site
of the short circuit and the presence of residual diesel fuel, reignited the fire
following discharge of the EBFSS (see Figure 11).
Source: OTSI
Figure 4: Fuel line misalignment 1
OTSI Bus Safety Investigation
Bus engine bay fire, Tongarra, 3 September 2018 8
Source: OTSI
Figure 5: Fuel line misalignment 2
Source: OTSI
Figure 6: Fuel line fittings
OTSI Bus Safety Investigation
Bus engine bay fire, Tongarra, 3 September 2018 9
Source: IVECO Australia – annotated by OTSI
Figure 7: OEM body build instruction (BBI)
Source: OTSI
Figure 8: Typical barb type fuel banjo fitting, bolt and sealing washers
OTSI Bus Safety Investigation
Bus engine bay fire, Tongarra, 3 September 2018 10
Source: OTSI
Figure 9: Diesel fuel residue from ruptured fuel line
Source: OTSI
Figure 10: Rotational heat patterns
OTSI Bus Safety Investigation
Bus engine bay fire, Tongarra, 3 September 2018 11
Source: OTSI
Figure 11: Location of electrical short circuit
Source: OTSI
Figure 12: Testing continuity of A/C system main fuse and battery main switch
OTSI Bus Safety Investigation
Bus engine bay fire, Tongarra, 3 September 2018 12
Evacuation of bus
2.16 At the time of the incident, the driver was nearing the end of the service and
only one passenger was on board. A review of the on-board CCTV recording
showed that when the driver was alerted by the EBFSS alarm and he had
brought the bus to rest, he notified the passenger to evacuate the bus.
2.17 The door controls functioned as required and the driver and passenger alighted
from the bus without injury or accident.
Fire extinguisher and alarms
2.18 An Australian Design Rule (ADR 58/00)5 specified that buses were to be
equipped with a readily accessible fire extinguisher selected and located in
accordance with the applicable Australian Standard6. Located next to the
driver’s seat was a 2.5 kg Dry Chemical Powder fire extinguisher7.
2.19 The EBFSS had a fire/heat warning sensor system that consisted of a
pressurised detection line placed in the engine compartment. When any part of
the detection line is heat affected and bursts, the system discharges a water
based fire suppressant agent including an aqueous film forming foam (AFFF).
The AFFF component is designed to cover any residual combustible liquid
fuels. The EBFSS also provides audible and visual dashboard alarms.
5 Australian Design Rule 58 Requirements for Omnibuses Designed for Hire and Reward 2006 6 Portable fire extinguishers and fire blankets – Selection and location. Australian Standard (AS) 2444—2001. 7 Routine service of fire protection systems and equipment. Australian Standard (AS) 1851—2012. AS 1851 required this type of extinguisher to be checked every six months. The EBFSS attached service record indicated it was last checked in March 2018.
OTSI Bus Safety Investigation
Bus engine bay fire, Tongarra, 3 September 2018 13
PART 3 FINDINGS
From the evidence available, the following findings are made with respect to the fire
on bus 7257 MO at Tongarra, NSW.
Contributory factors
3.1 The fire was likely initiated from a diesel fuel leak perpetuated by a short circuit
of the air conditioning wiring. Once the fire had begun it was fueled by diesel
fuel and other combustible material in the engine bay.
3.2 The fuse for the A/C remained intact, supplying a continuous source of energy
to the short circuit of the main A/C cable.
3.3 The power from the batteries to the engine bay was still live despite the driver
turning the ignition off. This meant the fire could reignite after discharge of the
EBFSS.
Other findings
3.4 The driver was unable to extinguish the fire using the on-board fire extinguisher.
3.5 The engine bay fire suppression system activated, but it is likely that, while
initially suppressing the fire, the fire reignited due to a continual supply of
energy to the short circuit of the A/C main cable.
OTSI Bus Safety Investigation
Bus engine bay fire, Tongarra, 3 September 2018 14
PART 4 RECOMMENDATIONS
It is recommended that the following additional safety actions be undertaken by the
specified responsible entities.
Bus operators
4.1 Review maintenance and inspection systems to ensure the integrity of fuel
system components.
OTSI Bus Safety Investigation
Bus engine bay fire, Tongarra, 3 September 2018 15
PART 5 APPENDICES
Appendix 1: Sources and References
Sources of information
• Premier Motor Service
• Transport for NSW
References
• Australian Design Rule 58 – Requirements for Omnibuses Designed for Hire and
Reward 2006
• Australian Standard (AS) 2444—2001. Portable fire extinguishers and fire blankets
– Selection and location.
• Australian Standard (AS) 1851—2012. Routine service of fire protection systems
and equipment
• DeHaan. J.D.; Icove.D.J., Kirk’s Fire Investigation (2012) Pearson 7th Ed.