A Shot to the Eye – Fire Hydrant Failure

John R. Yannaccone, P.E., Principal Mechanical Engineer
Incident Description: A water authority worker performed flow testing of a fire hydrant to measure flow rate and pressure. After gathering the measurements, the worker was shutting down the hydrant with a wrench by rotating the valve stem. As the valve was being closed, the worker was struck in the eye with an object that displaced and damaged his safety glasses, resulting in a serious injury and loss of vision in his eye. Following the incident, a screw which was used to secure a weather cover to the top of the hydrant was found, dislodged.
Expert Analysis: There were two questions related to this incident: why did the screw separate from the top of the hydrant and where did the energy to propel the screw upward at a high velocity come from? The screw used to hold the weather cap in place protects the bearings on the valve from dirt and water, and should not be under any load under normal conditions. Inspection of the screw showed it was not broken but that the threads were corroded, which reduced their engagement with the top of the valve stem. While this would decrease the strength or holding ability of the screw, under normal operating conditions there is no force to cause it to separate from the valve. Continue reading “A Shot to the Eye – Fire Hydrant Failure”

Clogged Mulch Grinder Leads to Injury

Mulch Grinder

John R. Yannaccone, PE, Principal Mechanical Engineer
Case Synopsis: A mulch factory worker was injured while trying to clear a clog at the top of a discharge belt on the grinding machine. Reportedly, the machine would build up mulch near the top of the discharge conveyer, causing the conveyer to operate improperly. The plaintiff had shut down the machine and climbed the conveyer to clear the mulch clog near the top of the belt. To assist in doing this, he unbolted and removed metal covers over the upper conveyer shaft. According to the plaintiff, he could not clear all the mulch, so he called down to a coworker to start the machine and turn on the conveyer for a few seconds. The plaintiff was standing at the top of the conveyer with one foot on each side. When the conveyer was started, it reportedly shook enough to cause the plaintiff to lose his balance and he shifted his foot into the conveyer where it was pulled into the top of the machine, crushing the plaintiff’s leg and entrapping him at the top of the conveyer. Continue reading “Clogged Mulch Grinder Leads to Injury”

Sump Pumps System Failure Code: Non-Compliance

Sump Pump Expert Witness

James J. Shields, P.E., Mechanical Engineer
Case Synopsis – A homeowner previously installed a basement sump pump system for the removal of storm water. The system consisted of a float-operated AC-powered motor-driven centrifugal pump, which was mounted in a below ground sump tank. The discharge piping from the pump was run through the sump tank cover, and vertically through 1½” PVC piping and check valve (to prevent reverse flow runback) to an elevation of about 8 feet above the basement floor. From this position, the pump discharge piping was run across the basement ceiling to the interior basement wall, and from there to the outdoors.
In early February 2014, the owner decided to upgrade the system with a backup pump, which would activate automatically upon the loss of AC power to his home. The owner hired a plumbing contractor to install the backup system. Beside the installation of the backup pump and the associated appurtenances, the contractor was required to integrate the new system with the existing pump and system. As reported, the modified system was later completed and tested with both pumps operating independently and jointly in a combined system arrangement. Continue reading “Sump Pumps System Failure Code: Non-Compliance”

The Lack of a Latch

Platform Lift

John R. Yannaccone, P.E., Principal Mechanical Engineer
Case Description: In a truck, two laborers were moving tools and equipment, including a platform lift, to a jobsite. When they arrived at the site, one of the men climbed into the truck and began unloading the items. As he raised the top of the platform lift, one of the legs fell from its stowed position to the open position, landing on the other man’s hand, which was located on the tailgate of the truck. The impact of the lift’s leg caused several fractures and other related injuries to the man’s hand.  
Steps Taken: An inspection of the lift was conducted to determine why the leg opened when the lift was raised. The inspection revealed that, while the legs had brackets and pins to secure them in both the up and down positions, the pins had to be manually installed by the users. Though it would be obvious to the lift user if a pin was not inserted while in use, the same would not be so obvious to someone simply transporting the lift in the stowed position. The laborers unloading the truck were not involved in loading the equipment and were first exposed to the lift during unloading. It was unclear who had placed the platform lift on the truck or used it last.  Continue reading “The Lack of a Latch”

The Value of Product Reviews


John R. Yannaccone, P.E., Senior Mechanical Engineer
A mother purchased a hand-held clothing steamer from an online retailer. Soon after starting to use it, the steamer expelled a significant amount of boiling water that landed on the pant leg of the clothing she was wearing. This boiling water soaked the upper portion of one pant leg and caused significant burns to her upper thigh. The woman reported she had the top properly placed on the steamer at the time of the incident, but the boiling water came out of both the spout and around the steamer lid. This steamer was designed to quickly heat water to the boiling point, creating steam, which would be expelled out the front of the steamer to eliminate wrinkles in clothing.
Prior to conducting an inspection of the subject steamer, an exemplar steamer was ordered to evaluate the design and to perform tests to determine potential causes of water being expelled from the steamer. When ordering the exemplar steamer, it was noted that there were a significant number of negative reviews of the product, reporting similar issues with boiling water being expelled during use. Similar product reviews were posted on other sites that sold the steamer. Some of these reviews included information on how the steamer was being used when the water was expelled and were useful in showing how widespread the problem was. Continue reading “The Value of Product Reviews”

Use and Performance of Gurney Restraints


John R. Yannaccone, Senior Mechanical Engineer
Case Synopsis: An ambulance service and their employees were named as defendants in a case where a vehicle crossed the centerline of the road and impacted the front of the ambulance. The plaintiff alleged that the ambulance crew failed to properly secure her to the gurney, which resulted in her moving forward during the crash and sustaining injuries that would have been prevented had she been properly restrained. According to the information available, the patient was still restrained on the gurney after the crash but slid forward, leaving her head and neck above the top of the gurney.
Plaintiff’s expert claimed she had been secured by the three cross straps, but that the ambulance crew had failed to use the shoulder straps provided by the gurney manufacturer. The expert opined had the patient been properly secured to the gurney using both the cross straps and shoulder straps, she would have been fully contained within the footprint of the gurney and would not have been injured during this incident. Continue reading “Use and Performance of Gurney Restraints”

The Humpty-Dumpty Effect

Rock Climbing Expert Witness

Thomas Cocchiola, P.E., CSP, Mechanical Engineer
Case Synopsis: A school purchased a portable rock-climbing wall for summer camp sessions. For safety purposes, a belay rope is typically used to prevent climbers from slipping and falling. Most rock walls require a partner to hold a belay rope for each climber, but the manufacturer equipped the subject rock wall with an automatic belay fall protection system that eliminated the need for climbing partners. Continue reading “The Humpty-Dumpty Effect”

Wheelchair Lift Won’t Quit Its Run

School Bus Lift

John R. Yannaccone, P.E., Senior Mechanical Engineer
Case Synopsis: One morning, a wheelchair-bound student was being picked up by a school bus equipped with a commercial wheelchair lift. As the lift containing the wheelchair-bound student was being raised up to the bus, the lift continued to run and then began to fold to a stowed position. The attendant inside the bus was able to get the student safely into the bus as the lift was folding. The driver, who was operating the lift, caught her arm in the mechanism while attempting to prevent the student from falling as the lift folded.
Expert Analysis: Inspection of the wheelchair lift revealed it was in good condition, but did have some damage from extrication of the driver’s arm. The electrical components of the lift were inspected and tested, which failed to show any problems that would explain why the lift continued to run when the operator released the controller. Additional inspection of the solenoid, which provides power to the motor for the hydraulic pump, showed evidence of arcing and possible welding on the contacts. Welded/sticking of this contact would continue to supply power to the pump motor, and cause the lift to continue to run. Continue reading “Wheelchair Lift Won’t Quit Its Run”

If A Red-Light Camera Falls on a Car and No One Sees It, Who is at Fault?


John R. Yannaccone, P.E., Senior Mechanical Engineer
Case Synopsis: Early one morning, a motorist was traveling in the right lane of a roadway equipped with red-light cameras. As he approached an intersection, a pole supporting a red-light camera fell over and struck the hood of his vehicle. The impact caused moderate damage to the hood of the vehicle, and the driver sustained injuries as a result of the incident. It was believed the camera pole fell due to prior damage which had weakened it. The motorist retained counsel and pursued a claim against the driver’s under/uninsured motorist policy which would only be required to pay if the incident was caused by another motor vehicle. The insurance carrier denied the claim as they believed there was no evidence to support that the camera pole fell as the result of prior contact by an unknown vehicle.
Expert Analysis: By the time the plaintiff had retained an attorney, the fallen pole had been replaced and the damaged components had been discarded. Though a physical inspection was not possible, photographs retrieved from other red-light cameras at the intersection, as well as the records from the subject pole, were reviewed for analysis. Continue reading “If A Red-Light Camera Falls on a Car and No One Sees It, Who is at Fault?”