Mechanical Engineering Expert

What is Mechanical Engineering?
"The branch of engineering dealing with the design, construction, and use of machines"

Meet John R. Yannaccone, PE
Sr. Mechanical Engineer

John R. Yannaccone, PE graduated from Drexel University, Philadelphia, PA, with a degree in Mechanical Engineering. With a focus on mechanical defects, failure analysis and general system safety, and over 25 years of experience, John’s expertise extends to the investigation and analysis of child safety seats, seatbelts, seatbacks, restraint systems, industrial equipment, household appliances, forklifts, ladders, scaffolds, machine guards, wheelchair lifts & occupant restraints, patient lifts, and consumer products.

Additionally, John is a certified Child Passenger Safety Instructor and teaches classes on child passenger safety. A registered professional engineer in several states, John is also a member of numerous professional societies including National Academy of Forensic Engineers, National Society of Professional Engineers, American Society of Mechanical Engineers, among others. John is a nationally certified firefighter and emergency first responder, and has training and experience regarding the operation of emergency vehicles.

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Mechanical Engineer Expert

Areas of Expertise


Airbag Expert Witness

Airbag Expert

The mechanical engineer evaluates the design and deployment of airbag systems relative to the crash, and the protection provided to the occupant.

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Ambulance Expert Witness

Ambulance Transport Expert

When investigating a collision involving an ambulance the mechanical engineer will investigate issues regarding the unique occupant environment, transport of a previously injured occupant, and the impact of other occupants working while the vehicle is in motion.

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Child Seat Expert Witness

Child Seat Expert

When a child occupant is injured in a crash, the mechanical engineer will analyze the physical evidence, determine how the child seat was being used, evaluate the design of the child seat, as well as the factors contributing to the injuries.

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Consumer Products Expert Witness

Consumer Products Expert

The Mechanical engineer provides expertise in evaluating potential product cases including potential failures, warnings and design claims.

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Equipment Expert Witness

Equipment Expert

The mechanical engineer evaluates the incident, as well as the piece of equipment, to determine, analyze and render a professional opinion as to what occurred and the contributing factors.

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Seatbelt Expert Witness

Seatbelt Expert

The mechanical engineer will inspect, analyze and render an expert opinion regarding seatbelt design, performance and use, as well as identify factors when contributed to the occupant’s injuries.

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Wheelchair Transport Expert Witness

Wheelchair Transport Expert

Special equipment is needed to maneuver a wheelchair bound occupant into a vehicle, as well as safely secure the occupant and the wheelchair. When a mishap is alleged to have occurred, the mechanical engineer will evaluate the contributing factors to the incident.

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Mechanical Engineer Expert Witness Firm

For over 57 years, DJS Associates, Inc. has been, and continues to be, a trusted source of quality forensic consulting and litigation support services for the legal community, insurance industry, government entities, and the public and private sectors. Our global experience in all aspects of forensic investigation comprised of forensic engineering, technologies and animations is further complemented by an independent storage, inspection and conference facility to secure, test, analyze and document accident and crime scene evidence.

The many services and specialties of DJS Associates include a comprehensive expert referral network and dedicated educators in a wide range of disciplines, collision / accident reconstruction, and our innovative state-of-the-art forensic technology, such as 3D courtroom animations and 3D modeling. Effective and timely use of High-Definition Survey (HDS) 3D laser scanning and Event Data Recorder download, supplemented with forensic photography, videography and photogrammetry, have contributed to our reputation as a respected forensic consulting, technology and animations firm.

One of the newest technological advances being utilized by DJS Associates (FAA Licensed), in the architectural, preservation and forensic fields, is the use of Unmanned Aerial Vehicles (UAVs), otherwise known as Unmanned Aerial Systems (UASs), or drones.

Drones/UAV/UASs can be utilized to carry cameras, video cameras and/or 3D laser scanners into areas not accessible by terrestrial equipment. The ability of drones/UAV/UASs to fly over an incident area and/or collect data from otherwise inaccessible areas due to their location or height is unprecedented. Drones/UAV/UASs are considered to be the “next level” of data collection and preservation.
DJS Associates currently has 7 FAA licensed drone pilots.

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