Forensic Engineering Expert’s Testimony Admitted Despite his Reliance on an Article Written in 2014
Posted on March 28, 2025 by Expert Witness Profiler
This case arises from a fire that occurred on Plaintiff’s Insured’s property, for which Plaintiff alleges the following alternative claims against Defendant: (1) strict product liability; (2) negligence (resulting from product defects); (3) breach of implied warranty of merchantability; and (4) breach of implied warranty of fitness.
The most probable ignition source of the fire was the failure of the exhaust fan motor. The existence of lint shows that the fire originated from inside the subject fan rather than outside the fan.
The thermal cutoff (“TCO”) in the subject fan did not work as designed or intended in that it failed to shut off the motor to prevent the arcing and overheating from occurring.
Allstate designated Robert Longseth, PE, a forensic engineer with experience investigating both electrical and mechanical systems, as an expert in this case. On December 29, 2023, Longseth prepared an expert report regarding the cause of the fire. Broan-Nutone sought to exclude at trial the opinions of Longseth regarding whether the TCO in the fan was defective.
Forensic Engineering Expert Witness
Robert Longseth, PE has over 17 years as a Forensic Engineer and has been involved in over 1000 investigations both in electrical and mechanical systems. Longseth is a registered Professional Engineer in 12 states.
He is a Board-Certified Engineering Diplomat in Forensic Engineering, through the National Academy of Forensic Engineers, a Certified Fire Investigator, through the International Association of Arson Investigators, and a Certified Fire and Explosion Investigator through the National Association of Fire Investigators.
Discussion by the Court
Initially, Broan-Nutone’s motion to exclude fails to clearly state which part of Rule 702 it relies on. Instead, the motion challenges Longseth’s conclusions about the TCO and the fire’s cause, specifically his reliance on a 2014 article. The Court interprets this challenge as questioning whether Longseth’s opinion regarding the TCO and its role in the fire is based on “sufficient facts or data,” as mandated by Rule 702(b).
The article at issue is “Ventilation Fan Fires: Overheated Windings Lead to Failed Thermal Limit Switch,” published in the journal Fire Technology in 2014. The article describes a “recent increase in the occurrence of ventilation fan fires.” The focus of the paper is two models of Jakel motors that were manufactured between 2000 and 2003 and were designed for ventilation in small rooms, such as laundry rooms and bathrooms.
Longseth’s expert report states that “the lead to the thermal cut out was bent significantly as part of its installation.” The report then states that, “while the model number of the specific motor was not the same as the below article the evidence is consistent with [the article’s] finding.”
Broan-Nutone’s Arguments
Broan-Nutone raises the point that the fans and TCOs discussed in the article may not be the same as the particular fan and TCO at issue in this litigation. Longseth counters, acknowledging that the model number of the motor involved in this case was not the same as the model numbers in the article but asserts that the evidence is “consistent with the findings of [the article].” Ultimately, the Court finds no issue with Longseth’s use of the article in reaching his expert opinions.
Secondly, Broan-Nutone contends that the 2014 article’s reference to TCO installation standards is irrelevant. They argue that 2014 standards are not pertinent and that there’s no evidence about manufacturing and design knowledge relevant to the 2005 fan. However, documents Allstate obtained through supplemental discovery directly contradict this. As Allstate explains, Underwriters Laboratories industry standard notices from 1999-2003, possessed by Broan-Nutone by September 2003, state the same TCO lead bending standard (no closer than three millimeters from the thermal-link seal) as the 2014 article Longseth cites. Consequently, the Court finds Longseth relied on sufficient facts and data and will deny Broan-Nutone’s motion to exclude.
Held
The Court denied the Defendant Broan-Nutone, LLC’s motion to exclude Plaintiff’s expert Robert Longseth.
Key Takeaway:
The Court found that Longseth’s reliance on a 2014 article about ventilation fan fires, despite differences in motor model numbers, was permissible as the evidence was consistent. Furthermore, the Court rejected Broan-Nutone’s argument that 2014 standards were irrelevant, noting that supplemental discovery revealed identical TCO installation standards were in place and known to Broan-Nutone as early as 2003, supporting Longseth’s conclusions and demonstrating sufficient factual basis for his opinion under Federal Rule of Evidence 702(b).
Case Details:
| Case Caption: | Allstate Indemnity Company V. Broan-Nutone, LLC |
| Docket Number: | 1:23cv743 |
| Court Name: | United States District Court, Colorado |
| Order Date: | March 26, 2025 |
