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BFPA– An Invaluable Source of Technical Expertise

Special Reports

by Stephen Barrett – BFPA Consultant and Director of Systems Services Ltd comments upon the crucial role played by expert witnesses in litigation

Among the many every day devices where hydraulic and pneumatic systems are involved are bin lorries, lifts in shopping centres, road sweeping machines and fork lift trucks. Pneumatics and hydraulics, collectively known as fluid power systems, are generally used to move heavy weights and are often capable of exerting immense forces. As a result, their failure or misuse can have severe safety and legal implications.

In legal cases where the operation of hydraulic or pneumatic power is relevant, it makes sense to have access to an expert witness with sufficient expertise to answer questions definitively wherever possible. The British Fluid Power Association maintains close relations with a number of industry experts and can therefore refer interested parties to a selection of expert witnesses, many of whom have spent a lifetime in the relevant part of the industry. Among the clients who turn to us for advice are BAE Systems, JCB, Tata Steel and Jaguar Land Rover. If an expert witness on fluid power is necessary then there is no better place to turn.

One such expert is Stephen Barrett of Systems Services. Stephen is a qualified fluid power engineer with over 38 years in the industry. He has provided consultancy services to some of the biggest names in the world of engineering and has delivered training on fluid power and closed loop control topics to more than 800 delegates. He, like all BFPA consultants, would like to make his personal expertise available to people who are in need of an expert witness regarding these subjects. The following article, written by Stephen discusses the role played by expert witnesses and is illustrated by some of his own experiences.

Chris Buxton – CEO BFPA Ltd.

Systems Services is a consultant member of the British Fluid Power Association and the UK Motion Control Alliance. We have worked with clients across the aerospace, automotive, concrete and polymer industries, as well as many more. Our relationships with many of these clients have spanned decades, giving evidence of our commitment to service and support.

One among many possible examples of incidents involving fluid power systems that could result in legal cases would be the failure of a forklift while attempting to raise a load and damaging a row of storage racking, along with the goods that it contains. Another would be a bin lorry lift malfunctioning and injuring one of its operators. Yet another might involve a scrapyard's brand new compactor breaking down in a fashion that looks suspiciously like it has been damaged through misuse

Even more hair-raising is the possibility of the failure of an aircraft’s hydraulic systems; responsible for controlling the direction in which an aircraft flies. If the hydraulic control systems fail, the aircraft could conceivably be unable to descend, manoeuvre or land. In practice there will be a back-up mechanical system for smaller aircraft that will allow the pilot to control the aeroplane in the event of hydraulic failure. Larger aircraft are likely to have three or four hydraulic systems, making the loss of all of them extremely unlikely. Faults with hydraulic systems can nevertheless cause aircraft to be grounded, which will result in heavy costs for the operators and possible disputes over who is to blame.

Plenty of people who are experienced mechanics have no real understanding of how hydraulic systems operate. This may result in fluid systems like the excavator arm on a back-hoe loader being neglected by their operators. It can even end up with misguided efforts to diagnose and resolve problems ending with
a pressure sensor being attached at an inappropriate point, blowing apart and seriously injuring the person conducting the test. These kinds of incidents are often as much the fault of the supervisor as the technician being required to carry out the work.

We can provide the best advice available on whether an incident was a result of negligence or some other avoidable occurrence. We can assess whether an account of an event is realistic, based on the behaviour of which piece of equipment is technically capable. We can also assess whether expensive items of equipment failed as a result of a flaw in the manufacturing process, poor design or whether they were damaged in operation. Finally, we can shed light in cases where there is a lack of understanding as to why a particular incident happened and who was therefore at fault.

For legal cases where one party is arguing that the other is at fault and vice versa, solid technical advice can be of crucial assistance. The more plausible your expert witnesses, the better the likelihood of winning your case. For relevant cases, contacting Systems Services will give you access to industry leading technical expertise.

If you want the evidence provided by an expert witness to be considered during court proceedings it is important to be clear on whether the evidence is necessary to determine an issue that is crucial to the case. Courts need to give permission before evidence from an expert witness can be heard as part of
proceedings. They will generally do so immediately where the evidence is reasonably required to resolve the case.

If evidence from an expert witness is not deemed to be strictly necessary to resolve the case then the court will make a judgement based on the value of the
claim, the effects on the different parties and the costs of procuring the evidence. If evidence will shed light on a central issue of the case, without strictly being
necessary to determine the case one way or another, then it might still be permitted by the court.

Clarity over whether knowledge of fluid power systems is of critical importance or will shed significant light on a case is required before employing an expert witness on the subject. It should also be remembered that the expert witness has a duty to the court to provide accurate, full responses to the questions put to them. This is their primary responsibility, rather than to assist the party that called for them to give evidence.

If you think that expertise on fluid power systems might be necessary to help determine your case, please don't hesitate to get in touch and we'll advise you on what kind of information we can provide and the likely fees.

About the author.
Stephen Barrett MIET, MRAeS.

As a qualified Fluid Power Engineer, Stephen Barrett has over thirty-eight years’ experience in hydraulics and control systems within the Motion Control industry. In addition to extensive consultancy work Stephen is an experienced trainer having trained over 800 delegates in various fluid power and closed loop control subjects.

This email address is being protected from spambots. You need JavaScript enabled to view it. Tel.: 01205 724242

For general enquiries regarding Expert Witnesses in the Fluid Power Sector contact Yvonne Pearman at the BFPA on Tel.: 01608 647900, or This email address is being protected from spambots. You need JavaScript enabled to view it.

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