Fuel Quantity Measurement Systems Patents: Who Leads, Where the Gaps Are 2026
- 88.6% of all 35 records sit with just five assignees — this is a field with a dominant core, not an open one.
- Filings fell to zero by 2024 from 2021, a -100% swing that pre-dates the current publication lag window.
- G01F carries 68.6% of records flow and level measurement dominates the claim space; water detection and attitude compensation remain thin.
Filing growth compares 2021 (2 records) with 2024 (0) — a three-year span. 2024 is the most recent year we treat as complete: publication lags filing by roughly 18 months, so 2025 onwards are still filling in and any growth rate that ends there would understate the field. Top-5 share is the combined record count of the five largest assignees divided by all 35 records in scope (CR5), not by the ranked leaders only.
What this landscape covers
Fuel quantity measurement in aircraft rests on two competing physical principles: capacitance probes that infer fuel level from dielectric constant, and ultrasonic gauging that measures density and level acoustically. Both must compensate for attitude changes, probe contamination, water ingress and insulation faults, and the patent record in this dataset clusters tightly around those compensation problems rather than around the base sensing method itself.
The 35 records in scope span 2015 through the current filing year, drawn from applicants filing across the United States, the European Patent Office, and a smaller set of national offices including the UK, Canada and Germany.
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Filing trend and technology composition
Two views of the same 35-record set: how filing activity has moved year over year, and which IPC subclasses carry the claim weight.
Filing activity, 2017-2026
Filings peaked at 6 in 2018 and had fallen to zero by 2024 from 2 in 2021 — a -100% swing over that three-year span. 2025 and 2026 figures are still incomplete because publication typically lags filing by around 18 months, so the apparent drop in the newest years should not be read as the field's current trajectory.
Where the claims sit
G01F (flow, level and volume measuring) appears in 68.6% of the 35 records, making it the dominant subclass by a wide margin. B64F (ground installations for aircraft) and G01D (general measuring and recording) follow at 20.0% and 17.1%. Material analysis (G01N, 14.3%) and dispensing (B67D, 11.4%) show that water detection and contamination-handling claims exist but are comparatively sparse, and radar/sonar-adjacent G01S sits at just 5.7%.
Shares are the percentage of the 35 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Fuel Quantity Measurement Systems with Eureka
This page is one run against one query. Ask Eureka your own question about fuel quantity measurement systems and every answer comes back with the patent numbers behind it.
Try EurekaRepresentative and most-cited filings
EP1860408A1 — Fuel quantity indicating system for an aircraft
A fuel quantity indicating system is disclosed. The fuel quantity indicating system comprises a fuel quantity processor; and at least one remote data concentrator coupled to the fuel quantity processor and to a fuel tank of the vehicle. The at least one remote data concentrator limits the amount of energy entering a fuel tank to a level considered to be intrinsically safe.Filed by The Boeing Company; the intrinsic-safety energy-limiting architecture is the operative claim element for anyone integrating a remote data concentrator into a fuel tank sensing loop.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US4809174A | Aircraft energy loading method and apparatus | 26 |
| 2 | US5900535A | Method and apparatus for ultrasonic measurement of fuel quantity and density | 25 |
| 3 | US2751921A | Control apparatus | 15 |
| 4 | US20030061876A1 | Acoustic fluid-gauging system | 13 |
| 5 | US6968738B2 | Acoustic fluid-gauging system | 12 |
| 6 | GB2309524A | Determination of fluid quantity from density measurements | 12 |
| 7 | US3545650A | Capacitive liquid quantity indicating and shut-off system | 10 |
| 8 | EP1860408A1 | Fuel quantity indicating system for an aircraft | 9 |
| 9 | US5152688A | Fuel training apparatus utilizing a high flash point fuel substitute | 8 |
| 10 | US20220120599A1 | Capacitive fuel gaging system with resistive elements | 5 |
Citation counts reflect influence within the searched corpus and skew toward older filings; they are not a measure of current commercial relevance.
Each row carries its publication number; clicking a row searches Eureka by that number.
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Browse MCP servers →What the numbers mean for filing strategy
Three read-outs from the dataset that matter for a freedom-to-operate assessment or a new filing decision.
A small group holds most of the claim space
The top five assignees account for 31 of the 35 records in scope, or 88.6%. That leaves a genuinely long tail below fifth place, where the fifth-ranked assignee holds only 2 records. A new entrant is filing into a field where the core sensing and compensation claims are already occupied by a handful of established aerospace suppliers.
Activity dropped sharply through the last complete filing year
Filings ran at 2 in 2021 and had fallen to 0 by 2024, the most recent year that can be treated as complete given the roughly 18-month publication lag. The peak year on record remains 2018 at 6 filings. Whether this reflects market saturation of core gauging claims or a shift toward filing under different search terms is not resolvable from this dataset alone.
Flow and level measurement dominates; adjacent problems are thinner
G01F carries more than two-thirds of records, consistent with capacitance and ultrasonic gauging being the core mechanism under claim. Contamination and material-analysis claims (G01N, 14.3%) and dispensing-related claims (B67D, 11.4%) are present but far less dense, which is where a targeted filing is more likely to clear a clean path.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to fuel quantity measurement systems, with the prior art for and against each one.
Who holds the filings
Eight assignees account for the entire ranked set of 35 records, with the leader holding 19 and a sharp drop-off after fifth place.
One assignee holds more than half the dataset alone
The leading assignee's 19 records represent the largest single share of the 35 in scope, well ahead of the rest of the ranked field. That scale typically reflects an incumbent aerospace systems supplier defending an installed base of fuel gauging hardware across multiple aircraft platforms.
A tight group of five controls most of the claim space
Below the leader, four more assignees combine to bring the top-5 total to 31 records, or 88.6% of all records in scope. These are the names to track for freedom-to-operate work, since between them they cover most of the compensation and calibration claims layered on top of the core sensing methods.
The remaining assignees close out the dataset with single-digit filings
Once the top five are accounted for, the remaining three assignees close the field to 100% of the 35 records. There is no unranked residue in this dataset — every record in scope belongs to one of these eight organisations.
| Assignee | Recent year | YoY |
|---|---|---|
| The Boeing Company | 0 | -100% |
| Smiths Group plc | 0 | — |
| Honeywell International Inc. | 0 | — |
| Smiths Group Limited | 0 | — |
| Simmonds Precision Products, Inc. | 0 | — |
| Parker Hannifin Corporation | 0 | — |
| United Technologies Corporation | 0 | — |
| Sperry Corporation | 0 | — |
Where to take this analysis
The dataset points to a concentrated field with a thin set of under-claimed branches. The next step is usually narrower than a full landscape.
Map a single claim element against the leader's portfolio
With one assignee holding 19 of 35 records, a targeted claim-chart comparison against that portfolio will do more for a freedom-to-operate opinion than a broader search.
Explore this in Eureka →Check the under-claimed branches before drafting
Water detection, probe contamination diagnosis and insulation monitoring show materially lower filing density than core gauging claims and are worth a dedicated novelty search before drafting.
Run a novelty check in Eureka →Common questions on this landscape
The ranked dataset covers 8 assignees across 35 records, with a single leader holding 19 records — more than half the dataset. The top five combined account for 31 records, or 88.6% of all records in scope, leaving a steep drop to the remaining three assignees. This concentration means most of the core capacitance and ultrasonic gauging claims are already held by a small group of established aerospace suppliers, and any new filing strategy should start by mapping against that leader's portfolio specifically.
Filing activity peaked at 6 records in 2018 and had fallen to zero by 2024 from 2 filings in 2021, a documented -100% change over that span. However, publication typically lags filing by around 18 months, so 2025 and 2026 figures in this dataset are still incomplete and should not be read as evidence the field has stopped. The honest read is that the last fully observable trend point is 2024, and it shows a sharp decline from the 2018 peak.
Capacitance probes infer fuel level from the dielectric constant of the fuel, while ultrasonic gauging measures fuel density and level acoustically; both approaches appear in the search terms defining this dataset. The IPC composition shows G01F (flow, level and volume measuring) covering 68.6% of the 35 records, indicating that both methods are typically claimed under the same measurement subclass rather than split cleanly by sensing principle. Compensation problems common to both — attitude changes, contamination, water ingress — are what most of the differentiated claims actually protect.
The technology composition shows G01N (material analysis, covering water and contamination detection) at only 14.3% of records and B67D (dispensing) at 11.4%, both far behind the dominant G01F share of 68.6%. This gap suggests water-ingress detection, probe contamination self-diagnosis and insulation resistance monitoring are comparatively under-claimed relative to core level-sensing methods. A first claim in these areas would likely focus on a specific detection circuit or diagnostic method layered onto an existing gauging architecture rather than a new base sensing principle.
EP1860408A1, filed by The Boeing Company, claims a fuel quantity indicating system built around a fuel quantity processor coupled to a remote data concentrator that limits the energy entering a fuel tank to an intrinsically safe level. It is one of the most-cited records in this dataset alongside older acoustic fluid-gauging patents. Anyone integrating a remote data concentrator into a fuel-tank-adjacent sensing loop needs to design around the specific energy-limiting mechanism this filing describes, rather than avoid remote data concentrators altogether.
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Disclaimer. This page is generated from Patsnap Eureka data drawn from a limited snapshot of global patent and scientific-literature records, and is provided for general information and reference only.
Patent data carries inherent limitations: recent filings (typically the most recent 18–24 months) are under-counted due to standard publication lag; counts may be reported at either a patent-family or a patent-record basis and are not always directly comparable; classification, applicant-name, and citation data may contain errors, duplicates, or omissions; and the underlying search query defines and constrains the scope shown. As a result, the analysis may be incomplete or inaccurate and may not reflect the full technology landscape.
Nothing on this page constitutes an exhaustive prior-art, novelty, freedom-to-operate, or validity search, nor does it constitute legal, financial, investment, or professional advice, and it should not be relied upon as such. Any patent, commercial, or strategic decision should be verified independently and reviewed with qualified patent, legal, and domain professionals. Patsnap makes no warranties, express or implied, as to the accuracy, completeness, or fitness for any particular purpose of the information presented.
Machine translation. Assignee and organisation names originally recorded in Chinese, Japanese or Korean have been rendered into English by an AI translation step so that the tables stay readable. These renderings are best-effort and may not match a company’s registered English name; the original name is what the underlying patent record carries, and it is what any Eureka query launched from this page uses.