Tag Archives: Mechanical Engineer

Tractor-Trailer Sustains Severe Fire Damage

Tractor Trailer Fire Damage

R. Scott King, BSME, Principal Automotive / Mechanical Engineer ::::

A commercial tractor-trailer sustained severe fire damage during an overnight stay in a parking area of a heavily traveled interstate. No one was in the truck at the time of the fire; however, security surveillance cameras recorded the event and the video became an important element of the ensuing investigation.

A preliminary engineering review included a study of the truck’s recent maintenance and repair records, as well as an interview with the truck owner. This identified two areas on the truck that warranted a detailed visual examination. It also identified potentially relevant parties for the subsequent, joint-expert examination. Specifically, the truck owner produced service records reflecting battery and starter repairs performed one month before the loss. He also reported that after those repairs, he had trouble starting the truck, along with other electrical problems. He returned to the shop that performed the repairs; however, those complaints went unremedied.

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Sprinkler Piping Installation – Code NFPA 16D Violation


James J. Shields, P.E., Mechanical Engineer ::::

Case Synopsis – A housing development company began a large multi-dwelling housing construction project at a site in Southeastern Pennsylvania. The development company hired a General Contractor to design and construct the site along with the erection of hundreds of homes. The project was planned by the development company to require several years for completion. As a first step in the process, the General Contractor obtained a building permit and produced a set of overall design drawings for the entire site, along with a set of design details for home construction. As is commonly the case, the General Contractor was responsible for the hiring of all sub-contractors. In addition, before commencing the work, all sub-contractors were required to sign a construction agreement with the General Contractor.

Approximately one year after the housing project had begun and certain housing sections had been completed, the housing developer and a prospective homeowner entered into an Agreement of Sale. The homeowner moved into the home about six months after signing the Agreement and lived in the home uneventfully for close to nine years. However, at that time, a severe water leak emerged from behind the drywall in the second-floor master bedroom. The water deluge from the leak was so great that it flowed through the wall, flooding the second story floor and pouring down two floors to the basement before the source of the water leak could be located and isolated. A vertical section of drywall was removed to expose the source of the water, which appeared to be originating from the sprinkler piping, although the exact location of the leak was still unknown. When the sprinkler system valves were shuttered the leak stopped, although, by then the volume of water released had created significant damage. The water was being supplied from the Township Water System, and the shutoff valves were able to isolate the home sprinkler system from the water supply.

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Cargo Barrier Failure in Armored Car

John R. Yannaccone, PE, Senior Mechanical Engineer ::::

Case Synopsis: On a dark and foggy morning an armored car, occupied with a driver and guard, was transporting assorted monetary cargo. The guard was situated in a seat located in the rear cargo area. As the armored car was traveling down the road, the driver failed to see a stopped tanker and drove into its rear. Upon impact, the cargo in the rear of the armored car shifted forward and impacted the rear of the guard’s seat, driving him into the bulkhead separating the cargo compartment from the driver’s area. The guard sustained serious injuries resulting in partial paralysis.

Expert Analysis: Inspection of the armored car revealed that the damage to the guard’s seat was consistent with it being loaded from behind and deforming it forward. There was a small bar, intended to serve as a barrier, to prevent the cargo from shifting, which was heavily deformed and had separated from its mounting points, allowing the cargo to move forward during the crash. In addition to the inadequate strength of the barrier, the basic design of the low bar was not sufficient to prevent heavy cargo from getting to the guard seated in the cargo area.

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Vehicle Operator Fatally Burned While Napping

R. Scott King, BSME, Principal Automotive / Mechanical Engineer ::::

A vehicle operator was fatally burned when the parked, but running, vehicle she had been sleeping in caught fire. Eyewitnesses reported hearing the vehicle’s engine racing before the fire began. Physical evidence revealed the fire originated in the area of the engine compartment supporting the witnesses’ observations.

The expert for the deceased’s estate postulated that the fire occurred because the occupant depressed and held the accelerator pedal long enough to allow the engine and its exhaust system to overheat, thus igniting nearby combustibles. The expert also opined that the engine speed control system, which was a fully electronic one, lacked safeguards that would have detected the abnormal condition of holding the accelerator pedal applied on a stationary vehicle and should have reduced engine speed to prevent the overheat condition. Examples from defendant’s discovery materials demonstrated that the vehicle was designed with the ability to self-regulate engine speed during a variety of driving situations, many of which were used to safeguard the engine from catastrophic damage. This, combined with examples of prior, similar claims, provided the basis for the opinion that the manufacturer knew of the risks that became manifested in this case, and had the technology and means to eliminate it.

R. Scott King, BSME, Principal Automotive / Mechanical Engineer with DJS Associates and can be reached via email at experts@forensicDJS.com or via phone at 215-659-2010.

Giant Swing Fall

Zip Line Trees

John R. Yannaccone, PE, Senior Mechanical Engineer ::::

Case Synopsis: An employee of an outdoor adventure facility was participating in an in-house training scenario where the employees were to complete a rope course. One of the obstacles involved a giant swing that used a carabiner to connect the participant’s harness to a swing line attached to two trees. A second line was connected to a quick release and was used to pull or haul the participant approximately 25 feet up. The participant pulled a small rope to actuate the release mechanism, which dropped the haul line and allowed the participant to swing from the swing line.

Several other participants had safely used the giant swing on the day of the incident prior to the plaintiff’s turn. When it was his turn, the plaintiff went to the bottom of the swing where the operator (another employee) connected the two lines and the plaintiff was hauled up. When the plaintiff pulled the release rope, he was completely discharged from the swing and fell approximately 25 feet to the ground where he sustained serious injuries.

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EDR: An Independent Witness!

R. Scott King, BSME, Principal Automotive / Mechanical Engineer ::::

Among the two most common allegations of vehicle failure after an incident are unintended acceleration and brake failure. Experience has shown that each type of failure is rare but they can and do occur; however, when the allegations are coincident, the likelihood of such a simultaneous failure is even more remote. In these cases, the most plausible explanation is operator error; however, historically proving this has been difficult if not impossible. But new vehicle technologies and the event data recorder (EDR) are changing that.

By now, most claims personnel are aware that many vehicles are equipped with event data recorders capable of recording information relative to a collision. These devices have proven their worth to collision reconstruction engineers over and over. But what many are not aware of is that most new vehicles today are equipped with an electronic throttle control system that uses sensors, wiring, and algorithms to translate accelerator pedal position to the throttle control valve, located on the engine. Fewer still are aware that the EDR in many vehicles can record accelerator pedal position versus throttle control valve position. In simpler terms, the EDR can tell whether a vehicle accelerated on its own, or under driver command, via application of the accelerator pedal. Couple this with the EDR’s ability to record brake pedal application, it provides an independent “witness” of how the pedals were used in the moments preceding a collision.

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