Selected Case Studies
Futuretech Design has provided forensic engineering services for a wide variety of litigation including bulldozers, timber harvesting equipment (skidders and feller-bunchers), forklifts, chlorine and propane handling, hammer failures, vending machines, commercial and residential lawn mowers, hydraulic systems, manlifts, chainsaws, agricultural style rotary cutters, food and rubber conveyors, outboard motors, tractors, land clearing, hose couplings, machine and hand tools, home appliances, and automotive systems. Expert witness testimony was even provided for a case involving a Christmas turkey; believe it or not.
The circumstances associated with past cases include death on the high seas, foreign defendants protected by international treaty, insurers as plaintiffs, and non-English speaking litigants. A few interesting cases are outlined below.
Engine Fuel Pumps
Both these cases involved in-tank fuel pumps that continued to run after a collision. The fact that these cases were so similar is rare in forensic engineering work.
In the first case, a young lady was driving a her high performance sport coup. She lost control of the vehicle and struck a utility pole. Although the impact was quite damaging, the bulk of her injuries came from the resulting fire. She survived to spend months in a burn unit but died shortly after release.
Eyewitness reports indicated that the fire progressed with amazing speed and intensity. Investigation of the burned vehicle revealed a hole in the cast aluminum valve cover on the engine. The hole was in the direct path of the open end of the fuel supply tube mounted on the firewall. The tank was removed to gain access to the in-tank electric fuel pump. Bench testing indicated that the pump was operable and had probably fueled the fire.
The second case involved a mid-sized pickup truck with two young men returning from a deer hunting trip. They collided with another vehicle in a curve on a winding road. As in the first case, the accident injured the occupants significantly but they burned to death in the fire that followed. In this case too, melted engine compartment components in the line of discharge of the fuel supply tube were observed. The fuel pump proved to be operative as before. It fueled a violent fast moving fire.
These two cases provide a perfect example of events that on the surface appear similar but the physical principals involved in each are totally different.
The first case involves a gas clothes dryer purchased by the plaintiff. Unbelievably, he was living in an apartment that did not have gas available. Rather than exchange the dry for an electric one, he then purchased a propane cylinder and regulator from the local hardware store, and had it installed to fuel the dryer. The cylinder and regulator were the type used on outdoor cooking equipment. The dryer continued to perform even after he and his family relocated to a rent house that had natural gas available. The inevitable failure occurred in the rent house in the form of an explosion. The blast was so violent that doors standing open were blown closed nearly destroying the casings. The entire ceiling of the house was lifted causing significant damage.
Investigation of the dryer, cylinder and regulator revealed the discharge pressure of the propane was 50-times greater than the specified supply pressure for the dryer. Since the plaintiff was an engineer, the attorney was advised not to pursue the case. He was very thankful for the suggestion. The plaintiff did note that it dried the clothes really quick.
The second case involves a propane fired barbeque grill. The in-use cylinder was stored in the compartment below the grill along with a full spare cylinder. The pressure relief value on the spare cylinder was leaking and the small volume of escaping gas was ignited by fat drippings. It continued to burn slowly. Plaintiff became aware of the flame and removed the cylinder to the yard a distance from the grill. As the small flame continued, the service valve became hot. The poppet spring in the relief valve weakened releasing a flaming stream of propane that impinged on the wall of the house. The building was nearly destroyed.
In the Woods
Plaintiff was operating feller-buncher. These huge rubber tired machines are used to harvest timber. They are capable of cutting and simultaneously caring several entire trees in the 12" trunk diameter range. The trees are moved in the vertical position and gently laid down near the delimber. The limbs are then removed and they are loaded on to tractor trailer trucks as long wood.
In the course of his work, the operator backed his feller-buncher in to a tall stump. He was injured inside the cab by the impact. The cab design was analyzed in light of existing standards for internal clearances. It did not conform.
A municipal employee for a rural village was responsible for maintaining the gaseous chlorine supply to purify the community's drinking water. In checking the in-use chlorine cylinder, he concluded the it was empty and started the process of replacing it with a full one. He closed the service valve tightly and loosened the chlorinator (chlorine regulator). The chlorinator blew off the cylinder valve discharge port. Plaintiff suffered severe chlorine burns to his chest, back, and most importantly, his lungs.
Investigation of the bronze cylinder valve reveal large amounts of ferric chloride in its internal passages. Electron microscopy was used to find iron embedded in the valve seat and stem. This evidence along with scoring of the valve seat lead to the conclusion that corrosion from inside the cylinder had lodged in the valve and prevented it from closing. The cylinder had not been properly cleaned.
Truck mounted fork trucks are a common sight around the country. They are typically used to unload building materials at job sites. In the vernacular, they are sometimes referred to as ‘spiders'. To lower the load on the forks, it is necessary to move the lifting frame forward so the load will clear the front wheels. To prevent the machine from tipping forward retractable stabilizer feet are utilized.
Plaintiff was unloading lumber at a new home construction site in a coastal community. He lowered the stabilizers and attempted to lift the load off the delivery truck. The stabilizers sunk in the soil. The spider tipped forward and the lumber slipped off the forks. As the rear of the machine fell to the ground the operator was seriously injured.
Investigation of the stabilizer pads indicated that they produced a ground pressure much greater than a bulldozer. They were shown to cover too small an area.
Tarred, but not Feathered
An instrument tap is a relatively small pipe connection made in a much larger pipe. It is used to obtain process data from the contents of the larger pipe, such as temperature, flow or pressure. Occasionally, the instrument tap will plug and need to be opened.
Plaintiff was given the assignment of ‘rodding-out' an instrument tap on a petroleum tar line in a refinery. Not knowing the operating pressure of the line, he was surprised to discover that it was 500 PSI. Plaintiff was unable to restrain the tool. It was blown out of the clean out valve and he was doused with hot tar.
Inspection of the tool indicated that it was not fitted with a safety stop to prevent it from coming completely out of the gland fitting.
They call the Wind, Mariah
A wicket is a door within a gate. The gate was part of complete privacy fencing of the rear yard of an inner city residence. The property was rented to a single grandmother. She opened the wicket and stepped partially through to be sure her granddaughter was crossing the street safely. With her hand rested on the frame of the wicket, a puff of wind slammed the door shut and removed her thumb.
Investigation of the wicket revealed that it was uniformly balanced. There was no detectable tendency to move in either direction under its own weight. The hinge points formed a nearly perfect vertical line. Since the wicket was not fitted with a hydraulic or pneumatic door closer, it was free to move in reaction to any outside force even the lightest breeze. It weighed 140 lbs., so the impact when it struck the casing was substantial. Attempts to re-attach the thumb were not successful and the finger was lost for good.