Expert Witness Profiler

Tag: Engine

  • Avionics Expert Allowed to Opine on Engine Failure

    Avionics Expert Allowed to Opine on Engine Failure

    This case arises from an accident involving a Robinson R44 II helicopter, registration N442VB (“Helicopter”), that occurred on the evening of December 30, 2021, in Levy County, Florida. The Helicopter was being flown at night by the owner-pilot, Ronald Hicks (“Pilot Hicks”), from a local friend’s residence to his private property. At the time of the accident, Pilot Hicks had less than ten hours of night flight experience in helicopters and was not certified under Instrument Flight Rules (“IFR”). Mr. Hicks, Shelly Kate Hicks, and their two children sustained fatal injuries.

    Defendant filed a Daubert motion to limit the testimony of Plaintiffs’ accident reconstruction expert John Bloomfield.

    Avionics Expert Witness

    John W. Bloomfield is the President and owner of Bloomfield Research and Development and am the holder of twelve United States patents in the disciplines of electronics, robotics, avionics, medical electronics, ultrasonics, precision spread spectrum radio ranging, battlefield communications, cellular digital software, and electronic toys.

    He holds an engineering degree in systems engineering and has 35 years of experience in aircraft electrical and avionics system. He has also been involved in the investigation of hundreds of aircraft accidents.

    Want to know more about the challenges John Bloomfield has faced? Get the full details with our Challenge Study report.

    Discussion by the Court

    Qualification

    First, the Defendant argued that Bloomfield opined regarding “metallurgical issues,” namely, that steel debris caused engine failure, despite being unqualified to do so. However, the Court has reviewed Bloomfield’s qualifications and is satisfied that, based on his extensive experience, which includes investigating numerous aircraft accidents and examining component parts, he is qualified to opine that steel debris caused the engine failure.

    Reliability

    Second, the Defendant argued that Bloomfield’s opinion that steel debris caused a loss of torque is untested and entirely speculative and therefore unreliable. Plaintiffs responded that Bloomfield explained he could not test the debris because it was not preserved, and testing could not be performed under substantially similar circumstances. He instead based his opinion regarding the presence and size of steel debris on the gouges left on the crankshaft.

    Bloomfield explained that any debris that was between the gear and the crankshaft was lost when the engine was taken apart and wiped during the inspection. And he testified that it was not possible to replicate his theory of the crash in a testing environment.

    Though Bloomfield’s failure to test his contamination theory is not determinative, this Court is not absolved of its gatekeeping function.

    The Court found that Bloomfield met the Daubert standard. Bloomfield explained why, based on a variety of evidence including key indicators used by other accident investigators, he concluded that the helicopter’s engine was not under power when the helicopter crashed.

    He then explained, using other case studies for reference, why he believed the dowel pin in the engine fractured not upon impact but during flight, causing a cessation of engine power.

    Finally, he discussed how the fractured dowel pin was caused by the loose gear bolt found in the engine, which could in turn be caused by a loss of torque from debris on the crankshaft, and how the presence of such debris was evinced by score marks on the gear face and crankshaft face.

    Helpfulness

    Defendant argued that Bloomfield’s criticism of the National Transportation and Safety Board’s investigation, particularly his discussion of the NTSB’s failure to preserve alleged contaminants, is neither reliable nor helpful.

    Defendant is concerned that Plaintiffs are trying to backdoor in a spoliation claim at trial. The Court previously denied Plaintiffs’ motion for a finding of spoliation and sanctions based upon Defendant’s alleged failure to preserve contaminants on the engine. The Court is prepared to sustain objections to any attempts to circumvent this Court’s ruling, including any argument that Defendant intentionally destroyed evidence. However, Plaintiffs’ experts may, of course, discuss the lack of physical evidence of contamination and their inability to perform certain tests on the engine because it was cleaned during the investigation.

    To that end, this Court is satisfied that Bloomfield can also reliably opine as to the way the engine was handled after the crash. Bloomfield either personally observed the instances he described, or he explained how, based on his training and experience, these parts are typically handled during the inspection process.

    Held

    The Court denied the Defendant’s Daubert motion to limit the testimony of Plaintiffs’ accident reconstruction expert John Bloomfield.

    Key Takeaway

    The Court is satisfied that Bloomfield has demonstrated his opinion is reliable. To the extent Defendant wishes to challenge Bloomfield’s conclusions and their bases, vigorous cross-examination, presentation of contrary evidence, and careful instruction on the burden of proof are the traditional and appropriate means of attacking shaky but admissible evidence.

    Case Details:

    Case Caption: Law V. Avco Corporation
    Docket Number: 1:24cv3
    Court Name: United States District Court for the Northern District of Florida, Gainesville Division
    Order Date: November 04, 2025
  • Accident Reconstruction Expert’s Opinion on Crew’s Inadequate Response Admitted

    Accident Reconstruction Expert’s Opinion on Crew’s Inadequate Response Admitted

    Plaintiff Sky Jet sought economic damages related to the destruction of the left engine of its 1996 Beech 1900D aircraft.  Defendant VSE overhauled an engine part called a fuel control unit (“FCU”). Sky Jet claimed that the fuel control unit malfunctioned during two attempts to start to the aircraft, causing elevated internal engine temperatures, also referred to as “hot starts.”

    Sky Jet sued VSE for negligence in its overhaul of the FCU. Defendant VSE has disclosed Mark Pottinger as its retained expert. Sky Jet filed a motion to exclude a causation opinion by Defendant’s expert Pottinger as unreliable and irrelevant.

    Accident Reconstruction Expert Witness 

    Mark Pottinger is an aircraft accident investigation course graduate at the USC Viterbi School of Engineering and an affiliate member of the International Society Of Air Safety Investigators (ISASI).

    He is an instructor at the Aviation Safety and Security Program of the Viterbi School Of Engineering.  In 2013, Pottinger started his own consulting firm specializing in accident investigations and reconstructions. He develops trial exhibits for parties involved in complex aviation litigation. Pottinger also consults with clients who are or expect to be parties to litigation due to aircraft accidents or aviation activities.

    Get the full story on challenges to Mark Pottinger’s expert opinions and testimony with an in-depth Challenge Study. 

    Discussion by the Court

    Mark Pottinger

    Pottinger disclosed four reports. His initial report, dated November 15, 2023, explained that an “engine makes power by taking ambient air and drawing it through the inlet and into the compressor section of the engine,” before passing into a “single centrifugal impeller.” Pottinger also explained the role of pilots during starting procedures and the need for the pilot to “be vigilant for abnormal start conditions” and to “take immediate action to manage an abnormal start” at the risk of engine damage. 

    Pottinger reviewed the maintenance records for the engine. He noted that problems with the engine began a few weeks before the FCU was replaced. 

    Pottinger also inspected the engine. One of the straightening vanes was broken and cracked, and it had a broken weld on the top crossbar. Pottinger stated: “The impact of the broken straightening vane on engine operation, or what caused the damage to the vane, have not been determined.”  However, he found that whatever the cause of the hot starts, the flight crew failed to appropriately react by aborting when the internal temperature reached 900 degrees. Both hot starts reached 1,000 degrees. 

    It should be noted that Pottinger supplemented his report three times. The last supplement, dated October 7, 2024, is at issue in the current motion. His specific opinion was that “[t]he fluctuating engine parameters and the poor starting performance of the subject engine resulted from the damaged diffuser straightening vane.”

    Plaintiff filed a motion to exclude Pottinger’s opinion in his October 7 report that “a broken engine component called a ‘straightening vane’ caused ‘poor starting performance’ or ‘abnormal engine operation.’”

    A. Undisclosed Opinions

    Plaintiff’s first argument is that Pottinger should not be allowed to offer a previously undisclosed opinion that “the broken diffuser vane caused the hot start.” In response, Defendant stated that Pottinger never made such an assertion and will not testify to that effect at trial.

    While this might appear to resolve the issue, Plaintiff, in its reply brief, accused Defendant of “playing semantic games,” arguing that Pottinger uses the terms “diffuser vane,” “straightening vane,” and “diffuser straightening vane” interchangeably—suggesting they refer to the same component. Plaintiff contends that Defendant is drawing an artificial distinction between these terms to claim that Pottinger never offered the disputed opinion. The Court observed, however, that Plaintiff’s own filings also use these terms inconsistently, making the distinction unclear on both sides.

    The Court found the parties’ arguments on this issue confusing. Pottinger’s October 7 report does, in fact, contain an opinion about a “damaged diffuser straightening vane,” making it unclear what opinion Plaintiff believes was not disclosed.

    As a result, the Court denied Plaintiff’s motion without prejudice. It emphasized that Pottinger’s opinions are documented in his report, and any testimony he offers at trial must align with what is stated there. However, due to the current lack of clarity in the record, the Court declined to make a definitive ruling on whether a specific opinion was disclosed or not. If necessary, Plaintiff may revisit the issue during trial.

    B. Reliability

    Pottinger’s October 7 report states that he had previously searched the Federal Aviation Administration’s Service Difficulty Report (“SDR”) system “for incidents that could be informative respecting the subject engine.” The two SDRs he discovered showed a damaged diffuser system causing increased temperatures and fluctuating engine parameters.

    His specific opinion about the damaged diffuser straightening vane was based on the SDRs.

    Plaintiff contended that “there is simply too great an analytical gap between Pottinger’s SDRs and any conclusion that the broken straightening vane caused hot starts.”

    Plaintiff did not dispute that, in general, relying on SDRs is improper. Instead, Plaintiff argued that the SDRs cited by Pottinger involve situations too different from this case, creating an unacceptable gap in his reasoning.

    The Court reviewed Pottinger’s reports along with the SDRs and agreed that there are some differences between those incidents and the present case. However, the Court finds that the gap in reasoning is not significant enough to make Pottinger’s opinions unreliable.

    Service Difficulty Report

    Plaintiff argues that the Service Difficulty Reports (SDRs) cited by Pottinger are not relevant for three reasons. First, the SDRs involved loose or broken diffuser tubes, whereas the engine in this case had a broken straightening vane. Based on this difference, Plaintiff claims the SDRs do not support the conclusion that a single broken straightening vane could affect engine performance.

    The Court disagrees. As noted earlier, there is considerable confusion regarding the terminology and how these components relate to one another. In fact, Plaintiff’s own reply brief quotes Pottinger’s testimony, in which he suggests that diffuser tubes and straightening vanes function as part of the same system. This implies that Pottinger himself sees less of a distinction between the parts than Plaintiff claims.

    Pottinger has also explained that both components work together to direct airflow into the engine, and that disrupting this airflow could adversely affect engine performance. Given this explanation, the Court finds that the fact the SDRs refer to diffuser tubes does not, by itself, make them irrelevant or render Pottinger’s opinion unreliable.

    Plaintiff’s second and third objections are that neither of the SDRs involved a hot start or engine damage. But the Court found this unpersuasive. Just because the engine in this case was damaged by a hot start doesn’t mean the SDRs are irrelevant simply because they didn’t involve hot starts. Both SDRs describe abnormal engine behavior, which is central to Pottinger’s opinion.

    The Court held that Pottinger’s reliance on SDRs where such irrevocable damage did not ultimately occur did not present so great an analytical leap—especially considering his emphasis on the crew’s inadequate response.

    C. Relevance

    Plaintiff’s third argument is that Pottinger’s October 7 report is not directly relevant to its claim that the fuel control unit (FCU) caused the hot starts. Plaintiff maintains that the central issue is whether the FCU was the cause and argues that Pottinger’s discussion of the diffuser or straightening vane has no bearing on that question.

    However, the Court found that Plaintiff’s view of the issue is too narrow. While Plaintiff’s theory focuses on the FCU as the cause of the hot starts, the broader question in the case is what caused the engine damage. Plaintiff believes the FCU was to blame, but Defendant offers alternative explanations—including Pottinger’s opinion that other engine defects contributed and that the crew’s failure to respond appropriately was ultimately responsible.

    Plaintiff also argued that Pottinger fails to connect his mention of “poor starting performance” to the hot start events. But this overlooked Pottinger’s opinion that the crew’s inadequate response played a key role in causing the damage.

    In conclusion, the Court finds that Pottinger’s opinions are sufficiently relevant to the issues in the case.

    Held

    The Court denied the Plaintiff’s motion to exclude certain expert testimony of Mark Pottinger.

    Key Takeaway:

    Pottinger “carried out an extensive investigation,” including inspecting the engine and maintenance records. His findings were that the engine was having issues unrelated to the FCU. His examination of the engine found damage to the diffuser straightening vane and he proffered that the general rule is that the most “upstream” damage is usually a starting point for determining what went wrong. 

    He was able to rule out all potential causes except the broken diffuser straightening vane and pilot error. So although Pottinger ultimately relied on the SDRs, they were not the exclusive basis of his opinions. Pottinger also testified as to the distinctions between the SDRs and this case and explained why they were still persuasive. 

    Case Details:

    Case Caption: Sky Jet M.G. Inc. V. VSE Aviation Services, LLC
    Docket Number: 2:23cv2210
    Court Name: United States District Court, Kansas
    Order Date: June 13, 2025