Aerospace Engineering Expert Testimony on Helicopter Crash Admitted per Reliance on Scientific Literature

The plaintiff, a flight instructor, sued the defendant for a helicopter crash. The plaintiff retained an aerospace engineering expert witness to opine on what went wrong with the helicopter.

Zach Barreto

Written by
— Updated on September 8, 2021

Aerospace Engineering Expert Testimony on Helicopter Crash Admitted per Reliance on Scientific Literature

Court: United States District Court for the Middle District of Alabama, Southern Division
Jurisdiction: Federal
Case Name: Ferguson v. Lear Siegler Servs.
Citation: 2012 U.S. Dist. LEXIS 42342

The defendant argued the expert lacked the right experience for the case and that his findings were unreliable. The court denied the defendant’s motion to exclude the aerospace engineering expert’s testimony because the expert had relied on literature to form his conclusions.

Facts

This lawsuit stemmed from a TH-67 helicopter crash that seriously injured the plaintiff flight instructor. The plaintiff was supervising a student who was maneuvering a helicopter at low altitude. The plaintiff claimed that an uncommanded cyclic movement benched the cyclic controller, also known as the helicopter’s joystick, from the student’s hand. This movement allegedly caused the student to lose control of the aircraft. An uncommanded cyclic motion happens when the controller moves without pilot feedback.

The army investigated the accident and discovered barium contamination in the servo actuators of the aircraft. The plaintiff argued barium got into the helicopter’s hydraulic system by way of preservative fluid. The plaintiff claimed the barium in the helicopter’s hydraulic system triggered at least one of the actuators’ valves to lock. The stickiness was allegedly compounded by an overly accommodating filter that allowed large quantities of particulate matter to penetrate the hydraulic system. Then, the system was split into smaller parts and eventually wore gouges into metal. Finally, the valve seized temporarily causing the uncommanded cyclic movement.

The Plaintiff’s Aerospace Engineering Expert Witness

The aerospace engineering expert witness held bachelor and doctorate degrees in aerospace engineering. He was well-versed in flight mechanics and had theoretical experience regarding the nature and operation of a helicopter’s components. As Head of Aerospace Engineering at a university, the expert taught several courses on aerospace engineering, modeling, and simulating hydraulic systems. Furthermore, he conducted extensive work on servo actuator issues as well as general studies on helicopter flight dynamics. The expert was also licensed in Alabama as a professional engineer.

The expert witness opined that transient ‘sticking’ of a flight valve spool in the helicopter’s lateral main rotor cyclic flight servo actuators triggered the uncommanded movement. This sticking allegedly occurred in the hydraulic fluid for two reasons: First, the presence of barium dinonylnaphthalene sulfonate; second, the presence of particulate pollution. Scientific literature and other credible data, which the expert relied on to draw this conclusion, supported these possible causal factors.

Argument

The defendant questioned the aerospace engineering expert witness’s testimony for two reasons. First, the defendant claimed the expert lacked the requisite experience with servo actuators to testify as an expert. Second, the defendant argued the aerospace engineering expert’s findings were unreliable, even if the expert witness qualified as an expert. In preparing his work on this issue, the expert worked extensively on the possible effects of barium and particulate matter on servo actuators. He checked the available scientific literature and studied the servo actuator allegedly responsible for the crash. Moreover, the expert found the army’s study suggested a  link between the involvement of both barium and particulate matter in the servo actuators and the incident. The investigation allowed the expert to apply his general helicopter mechanics and flight experience to the issues in this case.

Discussion

The aerospace engineering expert witness had detailed experience of aerodynamics, servo actuators, and helicopter operation. Moreover, in this situation, he spent much time applying that information to the particular issue. The question was whether barium deposits and particulate pollution in the TH-67’S hydraulic system triggered the plaintiff’s uncommanded-cyclical movement. Therefore, the court readily concluded he was qualified to testify.

The court further noted the expert reviewed a mixture of peer-reviewed publications and other experiments. After reviewing, the expert concluded that barium contamination of servo actuators caused the incident. The court deemed that proof the expert relied on in drawing his conclusions was reliable. The expert conducted his methodology in a way consistent with engineering standards. Moreover, it was consistent with objective research finding.

Ruling

The court denied the defendant’s motion to exclude the aerospace engineering expert witness’s testimony.

Key Takeaways for Experts

This case illustrates the importance of relying on both research and experience when reaching expert conclusions. In this case, the expert researched the topic and using that research, applied both knowledge and experience to his testimony. Whenever possible, experts should seek out peer-reviewed literature that is generally accepted by the scientific community to support their conclusions.

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