Case Examples
Case examples
The case the Police got badly wrong
The unthinkable, a death occurs, and the Police vehicle examiner gets it completely wrong. The image is the rear arm/handle of a wheelchair, which failed during the impact sequence. The question arose as to why the vehicle, carrying the wheelchair user, slowed in a manner consistent with the sudden application of the brakes, and the following 32,000 kg MAM/GVW (Maximum Authorised Mass/Gross Vehicle Weight) Large Goods Vehicle was unable to stop and impacted the rear of the vehicle, causing the wheel chair frame to fail. The Police failed to check if the truck was loaded at the time of the incident, or indeed establish the vehicle's actual weight.
The Police Vehicle Examiner, who incidentally had no formal Motor Vehicle Engineering Qualifications, and no understanding of the operation of the braking system, was adamant the brakes must have come on because of a defect in the brake servo unit. The Police thus turned their attention on the firm, who are a leader in the field, who converted the vehicle for use by the wheel chair user.
I was appointed by the vehicle converter, and having downloaded the data from the vehicle's control unit, and with the co-operation from the vehicle manufacturer, the event was reconstructed, and demonstrated that the sudden slowing of the vehicle was as a result of the vehicle driver selecting 1st gear instead of 3rd gear when downshifting from 4th gear.
There was no defect with the braking system, and causation for this unfortunate event was a mistake by the vehicle user.
Technician planned to sell the parts on EBay
An interesting case, Leading UK dealer Group replaced the engine on this "luxury" vehicle under warranty. On test drive prior to return to the customer, the vehicle suffered fire damage.
On examination of the remains of the vehicle, I found the technician had decided not to fit the new high pressure common rail fuel system pipes supplied to him by his parts department. Following further investigation it was found he had planned to sell them on EBay instead.
Vehicle and employment lost.
An urban street on a midsummer evening
The image, reproduced by kind permission of Steve Hawkins, was carried by the regional press.
A scene of wholesale destruction, caused by a flammable liquid (an oil) contacting a hot surface, resulting in ignition of the oil, and the resulting fire damage.
Reconstruction testing confirmed the hot surface in question reached 380-420 degrees Celsius. The auto-ignition temperature of the subject oil (the temperature at which it will ignite on a hot surface) was 260 degrees Celsius.
Fire in the quiet of the night
In this case, the tractor, manufactured by arguably the leading tractor manufacturer in Europe, suffered spontaneous combustion some 3 days post last use. The event was recorded by CCTV, usefully placing the seat of the fire between the off side front and rear wheels, and in the area of the tractor battery.
Fortunately, the insurer's Field Engineer flagged the case immediately, and the tractor was not moved, to preserve the evidence, or more accurately avoid loss of items which occurs when the tractor is moved.
Having heard the suggestions of fermenting crop, rodent attack, and even arson (which must have been undertaken by the invisible man due to the CCTV) a joint examination was undertaken.
The ISOBUS unit was recovered, and noted to be a third generation part, the first two generations having been superseded, and to have a specific deformation pattern indicative with it being the cause of the fire.
Terra Trac Combine Harvesters
A leading agricultural insurer identified a very significant number of total losses of the Terra Trac variant of this particular combine harvester, and an even greater number with localised fire damage. Examination of the combines which suffered localised fire damage informed a reconstruction protocol to evidence the mechanism of heat development and fire. My conclusions were that the front axle design was not suitable for use on a harvesting machine. The analogy that the design rendered the machine allergic to crop was a good one to simplify the result of selection of this design. I produced a list of features of the design which presented a fire risk. I note the 20/21 year axle redesign addresses issues identified. Since redesign, I am not aware of any fires seated around the front axle.
Schoolboy error, major incident
Whilst undertaking the restoration of a TVR, the mechanic followed the process he had apparently learnt as a trainee in the 1960s. This involved putting a pair of locking pliers on a fuel pipe to prevent fuel loss. The mechanic had never heard of fuel pipe clamps, or considered removing the fuel tank prior to welding.
The resultant fire destroyed the TVR workshop and nearly a dozen TVRs.
TGX – engine failures and resultant fires.
Since 2015, 3 separate insurers have instructed me to examine TGX tractor unit engines fitted with several incarnations of the series 26 engine, the manufacturers chosen 6 cylinder 12,419cc diesel engine found in their TGX tractor unit.
The commonality of failure sequence is rapid unplanned disassembly, the specific mechanism being separation of a connecting rod from the crankshaft, holing to the engine cylinder block and resultant fire. The first model I examined was a 2008 model, and the most recent (the latest incarnation) was a 2021 model. My particular interest here is the commonality of failure sequence, and the resultant loss of power and fire development which often results in the vehicle coming to a stop in the live lane of the carriageway.
In discussions with the DVSA regarding the very significant number of TGX cases I have been instructed upon, the key point is public safety, and the numerous reports of the vehicle coming to a sudden stop, requiring the driver to escape a burning vehicle sometimes into a live lane of traffic. This case currently illustrates a contrast to other cases I have dealt with. In those the manufacturer instigated a redesign, and I am not aware of further fires. With the TGX, each incarnation has failed to address the underlying issues and the problem remains.
Contact Details
Leecookson@causationengineering.uk
Causation Engineering
Ground Floor
33 Load Street
Bewdley
DY12 2AS