Zunum Aero v. Boeing: Mixed Judgment in Hybrid Electric Aircraft Dispute
Electric aviation startup Zunum Aero brought sweeping claims against Boeing, Boeing HorizonX Ventures, and Safran entities spanning patent inventorship, trade secret misappropriation, investor rights breaches, and securities violations. After 1,068 days of litigation in the Western District of Washington, Judge Robart issued a split verdict — Boeing prevailed on inventorship and most contract claims, while Zunum won on trade secrets and tortious interference.
Startup vs. aerospace giant: a fractured verdict on electric aviation IP
Zunum Aero, an electric aviation startup that had attracted investment from Boeing HorizonX Ventures and Safran, filed suit on 2 July 2021 in the Western District of Washington alleging that its own investors had appropriated proprietary hybrid electric aircraft technology, interfered with business relationships, and misused confidential information disclosed under a 2016 Proprietary Information Agreement. The patents at the center of the inventorship dispute — US11110811B2 covering active voltage control for hybrid electric aircraft and US10589635B1 covering a thin-haul hybrid electric propulsion system — had been filed by Boeing, which Zunum alleged should have credited Zunum’s engineers as inventors.
After 1,068 days of litigation, Judge James L. Robart entered a mixed judgment on 4 June 2024. Boeing and HorizonX prevailed on the majority of Zunum’s affirmative claims: all Consumer Protection Act, Securities Act, fiduciary duty, implied covenant, and 2016 Proprietary Information Agreement claims were dismissed in Boeing’s favour. HorizonX also prevailed on its counterclaims enforcing the 2017 and 2018 Note Agreements. Critically, Boeing secured a declaratory judgment of correct patent inventorship, confirming Boeing’s named inventors on the two hybrid electric aircraft patents.
However, the verdict was not a clean sweep. Zunum prevailed against Boeing on tortious interference with a business expectancy and, most significantly, on its Washington Uniform Trade Secrets Act (RCW 19.108) claim — findings that suggest the court accepted some evidence that Boeing mishandled Zunum’s confidential technical information. Zunum also prevailed on the 2017 Investor Rights Letter claim against both Boeing and HorizonX. The public record does not disclose the quantum of damages awarded on Zunum’s successful claims, leaving open questions about net financial exposure for Boeing.
Filing to Mixed Judgment in 1068 days
1,068 days — nearly 3 years from filing to judgment, above average for complex IP/commercial cases
Mixed judgment: what each party won and lost at trial
Mixed judgment — a split verdict across 11 claim categories
A mixed judgment means neither party prevailed on all claims. Judge Robart ruled claim-by-claim across patent inventorship, trade secrets, consumer protection, securities, contract, and tort theories. This outcome is procedurally significant: post-trial motions, damages hearings, and potential appeals may follow on the claims where each side lost. The absence of a single prevailing party also complicates fee-shifting and costs allocation under applicable statutes.
Split trial verdictBoeing secures inventorship and defeats most contract claims
Boeing and HorizonX prevailed on the most commercially sensitive claim: the declaratory judgment confirming Boeing’s patent inventorship on US11110811B2 and US10589635B1. Boeing also defeated all Consumer Protection Act, Securities Act, fiduciary duty, and 2016 PIA breach claims. HorizonX’s counterclaims on the Note Agreements also succeeded. However, Boeing’s loss on trade secret misappropriation and tortious interference exposes it to damages and potential reputational risk in the electric aviation investment community.
Inventorship confirmed for BoeingZunum wins trade secrets and tortious interference — but loses inventorship
Zunum’s most significant victory is the Washington Uniform Trade Secrets Act finding against both Boeing and HorizonX, along with a tortious interference finding against Boeing — suggesting the court credited evidence that Boeing misused Zunum’s confidential technical disclosures and interfered with Zunum’s business relationships. Zunum also prevailed on the 2017 Investor Rights Letter. Nevertheless, Zunum’s loss on patent inventorship means it cannot assert ownership of the hybrid electric propulsion patents, a strategically limiting outcome for any commercial revival.
Trade secrets win; inventorship lostHybrid electric aviation IP: investor conduct under the microscope
This verdict signals that strategic investors in deep-tech startups face meaningful legal risk when handling confidential disclosures from portfolio companies — even when they prevail on contract and patent claims. The trade secrets and tortious interference findings against Boeing may deter similar conduct in future aerospace venture investments. For the hybrid electric aviation sector, Boeing’s confirmed inventorship of the two propulsion patents reinforces its IP position, but the trade secrets ruling introduces uncertainty about the provenance of ideas embedded in Boeing’s electric propulsion programme.
Investor conduct liability riskFull party and counsel information
| Role | Name | Type | Detail |
|---|---|---|---|
| Plaintiff | Zunum Aero Inc | Company | Electric aviation startup — developer of hybrid electric propulsion technology for regional aircraftSearch in Eureka ↗ |
| Defendant | Boeing | Individual | The Boeing Company and affiliated venture/investment entities; Safran SA and subsidiary entitiesSearch in Eureka ↗ |
| Co-Defendant | Safran SA | Company | Search in Eureka ↗ |
| Co-Defendant | Boeing HorizonX Ventures LLC | Company | Search in Eureka ↗ |
| Co-Defendant | Safran Corporate Ventures SAS | Individual | Search in Eureka ↗ |
| Co-Defendant | Safran Electrical & Power SAS | Individual | Search in Eureka ↗ |
| Co-Defendant | Safran Helicopter Engines SASU | Individual | Search in Eureka ↗ |
| Plaintiff counsel | Armand J Kornfeld | Attorney | Counsel for Zunum Aero IncSearch in Eureka ↗ |
| Plaintiff counsel | Benjamin F Heidlage | Attorney | Counsel for Zunum Aero IncSearch in Eureka ↗ |
| Plaintiff counsel | Brian T. Goldman | Attorney | Counsel for Zunum Aero IncSearch in Eureka ↗ |
| Plaintiff counsel | Charlotte Baigent | Attorney | Counsel for Zunum Aero IncSearch in Eureka ↗ |
| Plaintiff counsel | Colin Hagan | Attorney | Counsel for Zunum Aero IncSearch in Eureka ↗ |
| Plaintiff counsel | David J Shlansky | Attorney | Counsel for Zunum Aero IncSearch in Eureka ↗ |
| Plaintiff counsel | Demian A Ordway | Attorney | Counsel for Zunum Aero IncSearch in Eureka ↗ |
| Plaintiff counsel | Eliot M Harris | Attorney | Counsel for Zunum Aero IncSearch in Eureka ↗ |
| Plaintiff counsel | Jack Lovejoy | Attorney | Counsel for Zunum Aero IncSearch in Eureka ↗ |
| Plaintiff counsel | Michael S Shuster | Attorney | Counsel for Zunum Aero IncSearch in Eureka ↗ |
| Plaintiff counsel | Scott M Danner | Attorney | Counsel for Zunum Aero IncSearch in Eureka ↗ |
| Plaintiff counsel | Steven W. Fogg | Attorney | Counsel for Zunum Aero IncSearch in Eureka ↗ |
| Plaintiff counsel | Vincent G Levy | Attorney | Counsel for Zunum Aero IncSearch in Eureka ↗ |
| Plaintiff law firm | BUSH KORNFELD LLP | Law Firm | Representing Zunum Aero IncSearch in Eureka ↗ |
| Plaintiff law firm | Corr Cronin LLP | Law Firm | Representing Zunum Aero IncSearch in Eureka ↗ |
| Plaintiff law firm | HOLWELL SHUSTER & GOLDBERG LLP | Law Firm | Representing Zunum Aero IncSearch in Eureka ↗ |
| Plaintiff law firm | Shlansky Law Group LLP | Law Firm | Representing Zunum Aero IncSearch in Eureka ↗ |
| Plaintiff law firm | Williams Kastner And Gibbs (SEA) | Law Firm | Representing Zunum Aero IncSearch in Eureka ↗ |
| Defendant counsel | Aaron M Healey | Attorney | Counsel for BoeingSearch in Eureka ↗ |
| Defendant counsel | Cassidy O’Sullivan | Attorney | Counsel for BoeingSearch in Eureka ↗ |
| Defendant counsel | Chandler W Matz | Attorney | Counsel for BoeingSearch in Eureka ↗ |
| Defendant counsel | David A. Perez | Attorney | Counsel for BoeingSearch in Eureka ↗ |
| Defendant counsel | Dustin Michael Koenig | Attorney | Counsel for BoeingSearch in Eureka ↗ |
| Defendant counsel | Emily Michael | Attorney | Counsel for BoeingSearch in Eureka ↗ |
| Defendant counsel | Ian Rogers | Attorney | Counsel for BoeingSearch in Eureka ↗ |
| Defendant counsel | John C. Hueston | Attorney | Counsel for BoeingSearch in Eureka ↗ |
| Defendant counsel | Justin Michael Greer | Attorney | Counsel for BoeingSearch in Eureka ↗ |
| Defendant counsel | Karen Ding | Attorney | Counsel for BoeingSearch in Eureka ↗ |
| Defendant counsel | Madeline Dover Swan | Attorney | Counsel for BoeingSearch in Eureka ↗ |
| Defendant counsel | Matthew A Kairis | Attorney | Counsel for BoeingSearch in Eureka ↗ |
| Defendant counsel | Moez M. Kaba | Attorney | Counsel for BoeingSearch in Eureka ↗ |
| Defendant counsel | Sourabh Mishra | Attorney | Counsel for BoeingSearch in Eureka ↗ |
| Defendant counsel | Susan E Foster | Attorney | Counsel for BoeingSearch in Eureka ↗ |
| Defendant counsel | Tate Harshbarger | Attorney | Counsel for BoeingSearch in Eureka ↗ |
| Defendant counsel | Yegor Fursevich | Attorney | Counsel for BoeingSearch in Eureka ↗ |
| Defendant law firm | HUESTON HENNIGAN LLP (CA) | Law Firm | Representing BoeingSearch in Eureka ↗ |
| Defendant law firm | Hueston Hennigan, LLP (Newport Beach) | Law Firm | Representing BoeingSearch in Eureka ↗ |
| Defendant law firm | JONES DAY (DALLAS) | Law Firm | Representing BoeingSearch in Eureka ↗ |
| Defendant law firm | Jones Day (NY) | Law Firm | Representing BoeingSearch in Eureka ↗ |
| Defendant law firm | Jones Day (OH) | Law Firm | Representing BoeingSearch in Eureka ↗ |
| Defendant law firm | Perkins Coie (sea) | Law Firm | Representing BoeingSearch in Eureka ↗ |
| Presiding judge | Judge James L. Robart | Judge | Washington Western District CourtSearch in Eureka ↗ |
Official order — verbatim text
The mixed judgment reflects a careful claim-by-claim adjudication rather than a wholesale acceptance of either party’s narrative. Boeing’s success on the patent inventorship declaratory judgment is the most durable outcome — it carries issue-preclusive effect against future Zunum inventorship challenges on these patents. Zunum’s UTSA and tortious interference wins, however, indicate the court found credible evidence of improper conduct by Boeing toward its own portfolio company. The absence of Safran entities from the judgment entries suggests they were disposed of separately. The net commercial outcome turns heavily on the undisclosed damages quantum for Zunum’s successful claims.
US11110811B2 & US10589635B1 — Hybrid Electric Aircraft Propulsion
US11110811B2 claims active voltage control architectures for hybrid electric aircraft — a critical subsystem governing power distribution between electric motors and generator sources during flight phases. US10589635B1 covers thin-haul hybrid electric propulsion system design, addressing the integration of gas turbine and electric motor drive for regional aircraft segments. Both patents sit at the intersection of power electronics and aerospace propulsion engineering, application numbers US16/215073 and US16/289900 respectively, and were asserted by Boeing as its own inventions — a position the court ultimately confirmed.
These patents represent foundational IP in the nascent hybrid electric regional aviation market — a segment attracting significant investment from aerospace primes, tier-1 suppliers, and well-capitalised startups. Confirmed inventorship in Boeing’s name strengthens its position to enforce or license these patents against competitors developing similar propulsion architectures. For companies building hybrid electric aircraft powertrains, both patents now represent cleared Boeing IP that warrants formal FTO analysis before product development commitments are made.
Should you run an FTO against US11110811B2 and US10589635B1?
Any company developing hybrid electric propulsion systems, active power management electronics, or thin-haul electric aircraft platforms should treat these two Boeing patents as live enforcement risk following the court’s inventorship confirmation. The patents cover core architectural choices — voltage control topology and propulsion system integration — that are difficult to design around without impacting system performance. OEMs, Tier 1 suppliers, and eVTOL developers working in adjacent power management domains should assess overlap before committing to hardware designs.
PatSnap Eureka’s FTO Search Agent can map US11110811B2 and US10589635B1 claim scope against your product architecture in minutes, flag independent claims with the broadest potential reach, and surface prior art that may support validity challenges. Eureka also monitors the Boeing hybrid electric patent family for continuations and divisionals — ensuring your FTO analysis remains current as Boeing’s portfolio in this space expands.
Run a freedom-to-operate analysis on US11110811B2 to assess your product’s exposure
Run FTO in Eureka →Similar hybrid electric aviation IP and startup-investor trade secret cases
Cases involving hybrid electric aviation technology, startup-investor IP disputes, and trade secret claims in the W.D. Washington and related federal courts.
What this case signals for the electric aviation IP landscape
The Zunum v. Boeing outcome reshapes how startups and strategic investors should structure technology-sharing arrangements in the electric aviation sector.
Strategic investors face trade secret liability even when they win on contracts
Boeing prevailed on most contract claims but lost on trade secret misappropriation. This split outcome suggests that contractual information-sharing frameworks — like the 2016 PIA — may not fully insulate strategic investors from UTSA liability if confidential disclosures are mishandled. Deep-tech startups and their investors should audit NDAs and proprietary information agreements for gaps that courts may treat as inadequate protection.
Inventorship challenges by startups against corporate investors rarely succeed
Zunum’s loss on the declaratory patent inventorship claim is consistent with the high evidentiary bar for displacing named inventors on issued patents. Startups sharing technology with corporate partners should document inventorship contributions contemporaneously — through lab notebooks, timestamped disclosures, and invention disclosure forms — before investor relationships deepen and patent applications are filed.
Zunum v Boeing — key questions answered
Neither party achieved a clean victory. Boeing and HorizonX prevailed on patent inventorship, most contract claims, Consumer Protection Act, and Securities Act counts. Zunum prevailed on Washington Uniform Trade Secrets Act and tortious interference claims against Boeing, and on the 2017 Investor Rights Letter. The court entered a mixed judgment on 4 June 2024.
Two Boeing patents were central to the inventorship dispute: US11110811B2 (active voltage control for hybrid electric aircraft, App. No. US16/215073) and US10589635B1 (thin-haul hybrid electric propulsion system, App. No. US16/289900). Zunum alleged Boeing should not be the named inventor; the court ruled in Boeing’s favour on inventorship.
Yes. The court entered judgment in favour of Zunum and against both Boeing and HorizonX on Zunum’s claim under the Washington Uniform Trade Secrets Act (RCW 19.108 et seq.). The damages quantum associated with this finding is not disclosed in the public judgment record.
Safran SA, Safran Corporate Ventures SAS, Safran Electrical & Power SAS, and Safran Helicopter Engines SASU were named as defendants. However, the final mixed judgment does not enter rulings against Safran entities on any claim, suggesting they were disposed of at an earlier stage of proceedings or dismissed — the public docket does not confirm the precise mechanism.
The court’s declaratory judgment confirms Boeing as rightful inventor on US11110811B2 and US10589635B1, covering active voltage control and thin-haul hybrid electric propulsion. This ruling carries issue-preclusive weight against future Zunum challenges and reinforces Boeing’s ability to enforce or license these patents. Competitors developing similar hybrid electric propulsion architectures should conduct freedom-to-operate analysis against both patents.
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