Mechanical Engineering Expert Barred From Testifying for Not Testing Alternative Design
Posted on August 25, 2025 by Expert Witness Profiler
Plaintiff Paul Johnson sustained severe injuries while operating a RIDGID K-6200 drain cleaning machine (“subject machine”) at his workplace. He sued the machine manufacturer, Defendant Ridge Tool Company (incorrectly identified as Ridge Tool Manufacturing Company, Inc.), asserting claims for negligence, product liability, and failure to warn.
Plaintiff brought this lawsuit contending that Defendant manufactured an unreasonably dangerous and defective machine without an appropriate fixed guard that would have prevented Plaintiff from having to hold a rotating cable in his hand that could suddenly twist and kink and pull him. Plaintiff also challenged the adequacy of Defendant’s warnings and argued that personal protective equipment (PPE) was insufficient to protect users from the known hazards associated with this type of drain cleaning machine.
In support of his claims, Plaintiff relied on two experts, Chad E. Jones, a mechanical engineer, and Cynthia M. Rando, a certified human factors professional. Following the completion of discovery, Defendant filed motions to exclude the testimony of both experts.
Mechanical Engineering Expert Witness
Chad E. Jones is a certified machine safety expert who is licensed in seven states and has worked as an engineer since 1996. He has a Bachelor of Science in Mechanical Engineering from Clemson University. Jones has participated in and led industrial accident investigations and participated in in-depth process safety audits. This work has included equipment design, machine safeguarding, cost estimating and safety compliance. He has designed HVAC and plumbing systems for commercial, industrial, and private clients.
Human Factors Expert Witness
Cynthia M. Rando is a certified human factors professional who has worked in the human factors field for approximately twenty years. She is Vice President of the Board of Certification in Professional Ergonomics (Human Factors). Rando received her B.S. and M.S. in Human Factors Engineering from Clemson University and an MBA from Northeastern University. She has also served as an associate professor at University of Houston Clearlake providing instruction in Human Factors, Safety and Ergonomics course material.
Discussion by the Court
Chad Jones
i. Qualifications
Defendant argued that Jones was not qualified because, despite being a mechanical engineer, he did not have any experience with the machine at issue or with drum-style drain cleaning machines generally. Defendant also contended that Jones’ purported experience with guarding mechanisms as they relate to industrial machine presses bore no relation to this case, as a machine press was entirely different from a drum-style cleaning machine.
While Jones’ personal experience with drain cleaners is limited, and he is not familiar with the subject machine, the Court held that his professional experiences qualify him to opine here. Jones is certified as a machinery safety expert and has worked in the area of machine safeguarding since March 2019. True, he may not have actual experience with the particular machine in this case, but he need not be the best expert in the field in order to be qualified.
ii. Reliability
Defendant argued that even if Jones’ qualifications pass muster, his opinions are nonetheless unreliable because he failed to perform any testing of his purported reasonable alternative design. Jones opined that Defendant was required to include a fixed guard over the rotating cable to prevent injury. It is undisputed that Jones did not engage in any physical testing of the proposed alternative nor did he conduct any mathematical calculations or models.
Indeed, Jones conceded that he has not spoken to any users of the equipment or industry professionals nor did he design or test his own fixed guard or physical prototype, use a computer program to design or simulate a fixed guard, perform calculations or drawings to demonstrate how an alternative guard would fit onto the machine, take an exemplar guard and try to apply it to the machine, or perform calculations, modeling, or other analysis to assess if an alternative guard would impact the speed or ability of the cable’s rotation.
Plaintiff’s contention that Jones need not test his alternative design is premised upon his assumption that the fixed guard is an “industry standard.” On this point, Plaintiff claimed that three of Defendant’s competitors use a fixed guard and thus the Court should presume this is what the industry requires. But that is too great of a leap in logic.
Jones did not conduct any type of analysis that would make up for his lack of testing of the proposed alternative design. While Plaintiff contended that Jones included detailed designs, an economic study, preliminary drawings, and his own risk-utility testing, the Court does not find that information on the cited references or anywhere else in the report.
Cynthia Rando
After reviewing certain materials and taking Plaintiff’s hand measurements, Rando opined as follows:
➢ The primary root cause of the incident involving Plaintiff and the K-6200 Drain Cleaning machine was failure to effectively address hazards created by the design and operation of the K-6200 Drain Cleaning machine through standard design controls.
➢ Defendant demonstrated negligence through their failure to effectively assess and control risk and the violation of accepted standards of practice pertaining to risk management and the design for human safety.
➢ Additionally, the failure to provide the correct personal protective equipment (PPE), including unsafe recommendations made by Defendant to utilize a “one size” glove that allowed for a loose fit for individuals representing a smaller anthropometric hand size range, introduced unacceptable added risk and significant potential for injury.
➢ The reliance on the user manual to provide the necessary information regarding safe operation of the device by Defendant and the expectation that the manual was the hazard control method was negligent. This approach passed the responsibility of safety to the end user despite the awareness of the potential for significant injury based on the design of the equipment and recommended method of operation.
➢ The user manual was not written in an easy-to-understand manner, including conflicting safety instructions and recommendations for postures that would create increased risk of injury to the operators.
➢ The manual violated ANSI Z535 standards and recommended unsafe operations to the end users but advertised them to be “safe.”
➢ These issues represent the root cause and contributing factors to the injury incurred by Plaintiff on August 17, 2019.
i. Reliability
Defendant argued that Rando’s opinions on the user manual are irrelevant to the causation analysis and unreliable because she failed to either offer or test any reasonable alternative warnings.
After reviewing Rando’s expert report, the Court concluded that Rando did not offer a specific opinion about the adequacy of the warning label. Indeed, her opinions as to “Caution and Warnings” are couched in the context of analyzing the user manual which, as noted, Plaintiff did not read.
Rando never addressed whether the warning label affixed to the machine was inadequate or failed to capture Plaintiff’s attention. Because her opinion focused solely on the user manual Plaintiff never read, the Court held that it is not relevant.
Even if the Court did interpret Rando’s opinion as encompassing the warning label, her failure to draft or test any proposed alternative warnings still rendered any such opinion unreliable.
Last, Plaintiff pointed to Rando’s opinion on personal protective equipment (PPE) that Defendant’s standard one size fits all glove—which Plaintiff admittedly did not use here—was unsafe, but that has no bearing on his failure to warn claim. In the end, these “unsafe recommendations” were included in the user manual, which, as already discussed, Plaintiff never read. Therefore, the Court held that her opinion on PPE is similarly irrelevant.
Held
The Court granted the Defendant’s motions to bar the testimony of Plaintiff’s expert witnesses, Chad Jones and Cynthia Rando.
Key Takeaway:
An expert can overcome the lack of testing by adhering to the standards of intellectual rigor demanded in their professional work. However, Jones did not conduct any type of analysis that would make up for his lack of testing of the proposed alternative design.
Case Details:
| Case Caption: | Johnson V. Ridge Tool Manufacturing Company, Inc. |
| Docket Number: | 1:21cv1939 |
| Court Name: | United States District Court, Illinois Northern |
| Order Date: | August 22, 2025 |
