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Run your analysis now →https://www.patsnap.com/resources/blog/rd-blog/auxiliary-power-units-for-aircraft-patent-landscape/ · Patsnap · data cut-off 2026-07-31 · downloaded from the live page
Patent Landscape · Aircraft SystemsAuxiliary Power Unit Patents in Aircraft: Who Files, What They Claim
- 66.5% concentration. The top 5 assignees account for 103 of the 155 records in scope — this field is held by a small group of engine and airframe majors, not a fragmented crowd.
- Filing has cooled since 2019. Filings peaked at 19 in 2019 and the 2022 midpoint sits back at 10, a flat-to-declining trend rather than a growth curve — though the most recent year is always understated by publication lag.
- Claims cluster in two IPC subclasses. B64D aircraft equipment and F02C gas-turbine plants together dominate the record set, while control, combustion and electric-machine subclasses each hold single-digit percentage shares.
155
Published Records
66%
Top-5 Share of All Records
-77%
3-Yr Growth (lag-adjusted)
US
Leading Jurisdiction
Published byPatsnap Research··7 min readSourced from Patsnap Eureka
Overview
What this landscape covers
Auxiliary power unit patenting sits at the intersection of gas-turbine engineering and aircraft systems integration: claims range from bleed air supply and starter-generator design to altitude start capability, fuel consumption and maintenance interval improvements. The search scope pulls 155 published records filed or published between 2015 and mid-2026, drawn from IPC classes covering gas-turbine plants (F02C6, F02C7) and aircraft equipment (B64D41).
Records here are counted as patent families, which is the fairer unit for comparing assignees across jurisdictions since it removes the effect of continuation filings and multi-country duplicates. The dataset skews toward established turbine and airframe manufacturers rather than new entrants, and receiving-office data shows filing activity concentrated in the United States and at the EPO.
Filing activity and technology composition, 2015–2026
Source: Patsnap Eureka. Assignee ranking and totals. Derived from a Patsnap search on Auxiliary Power Units for Aircraft covering 2015–2026, data cut-off 2026-07-31. Counts reflect published records only and shift as new filings publish.Run this in Eureka MCP
The Data
Filing trend and technology composition
Two views of the same 155-record set: how filing volume has moved year over year, and how those records split across IPC subclasses.
Filing trend, 2017–2026
Filings rose from 10 in 2017 to a peak of 19 in 2019, then settled near the 2022 midpoint of 10 — a flat-to-declining pattern through the most recent full years. The final year in the chart is partial because publication typically lags filing by around 18 months, so 2026's true total will read higher once later filings publish.
IPC subclass composition
B64D (aircraft equipment) appears in 78.1% of the 155 records and F02C (gas-turbine plants) in 60.0%, confirming that most APU claims are written jointly across airframe integration and turbine engineering. Smaller shares in F01D, B64C, H02K, F02B, F02D and F23R show where claim activity is thinner — each under 10% of records — though a record can carry more than one class, so these figures do not sum to 100%.
Shares are the percentage of the 155 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Source: Patsnap Eureka. Filing trend and technology composition. Derived from a Patsnap search on Auxiliary Power Units for Aircraft covering 2015–2026, data cut-off 2026-07-31. Counts reflect published records only and shift as new filings publish.
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Most-cited records in this landscape
Representative Filing
Auxiliary power unit with integral firebox — Honeywell International
HONEYWELL INTERNATIONAL INC.
An auxiliary power unit with integral firebox provides an integral unit for aircraft to utilize an APU without the use of a separate firebox. The design comprises a turbomachine intake air duct secured to an enclosure with a bleed air port extending from the combustor to outside of the enclosure, with an APU secured inside. The unit is described as retrofittable to existing aircraft or installable in newly built aircraft.Filed by Honeywell International, published 2006-10-05.
Highest-citation records
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US20060260323A1 | Aircraft with disengageable engine and auxiliary power unit components | 388 |
| 2 | US6305156B1 | Integrated bleed air and engine starting system | 195 |
| 3 | US7805947B2 | Aircraft with disengageable engine and auxiliary power unit components | 108 |
| 4 | US5201798A | Multifunction integrated power unit and power transfer apparatus therefor | 88 |
| 5 | US6450447B1 | Auxiliary power unit for an aircraft | 65 |
| 6 | US7251942B2 | Integrated gearless and nonlubricated auxiliary power unit | 62 |
| 7 | US3680309A | Two-spool auxiliary power unit and control means | 61 |
| 8 | US4759178A | Aircraft auxiliary power unit | 59 |
| 9 | US5309708A | Multifunction integrated power unit | 57 |
| 10 | US20080066470A1 | Advanced hydrogen auxiliary power unit | 53 |
Citation counts favour older filings simply because they have had more time to accumulate citations inside this corpus — treat them as a measure of influence on later filings, not of current commercial relevance.
Each row carries its publication number; clicking a row searches Eureka by that number.
Source: Patsnap Eureka. Citation counts and representative records. Derived from a Patsnap search on Auxiliary Power Units for Aircraft covering 2015–2026, data cut-off 2026-07-31. Counts reflect published records only and shift as new filings publish.Run this in Eureka MCP
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What the numbers say
Three read-throughs from the concentration, trend and citation data above.
Concentration
66.5%
of 155 records held by top 5
A small group holds most of the claim space
The top 5 assignees account for 103 of 155 records and the top 10 for 130 — 83.9% of the field. New entrants are filing into a space where the largest engine and airframe manufacturers already hold a majority of the claims, which raises the bar for a freedom-to-operate review before committing to a design direction.
Based on the 30-company ranked list returned for this search.
Momentum
19 in 2019
peak filing year
Filing has not grown since its 2019 high
Volume climbed from 10 in 2017 to 19 in 2019, then eased back toward the 2022 midpoint of 10. That pattern reads as flat-to-declining rather than an emerging technology still gaining filers, though the last one to two years of any trend are always undercounted by publication lag.
Trend covers 2017 through the 2026 data cut-off.
Citation influence
388 citations
top-cited record
Early disengageable-component filings still anchor the field
The most-cited record in this set, on disengageable engine and APU components, carries 388 citations — well ahead of the next-ranked records. High citation counts here reflect age and foundational status inside the corpus, not that the underlying approach is still the preferred design today.
Citation counts are corpus-internal, not global.
Eureka AI Agent
Looking for what nobody has claimed yet?
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to auxiliary power units for aircraft, with the prior art for and against each one.
Source: Patsnap Eureka. Co-assignee relationships and derived observations. Derived from a Patsnap search on Auxiliary Power Units for Aircraft covering 2015–2026, data cut-off 2026-07-31. Counts reflect published records only and shift as new filings publish.Run this in Eureka MCP
Players
Who is filing, and where the room to move sits
The ranked list of 30 companies is dominated by a handful of engine OEMs and airframe integrators, with a long tail of single- or low-digit filers behind them.
Leader
49 records
leading assignee
One filer sits well ahead of the field
The top-ranked assignee holds 49 of the 155 records in scope, more than four times the fifth-place count of 7 — a gap wide enough that any competitive filing strategy here has to account for one dominant portfolio rather than a level field.
Counted in patent families.
Mid-field
7 at fifth, 5 at tenth
records held
The drop-off after the leader is steep, then flattens
Positions five and ten sit close together at 7 and 5 records respectively, meaning the real competitive tier below the leader is fairly even — no single challenger is close to catching up on volume alone.
Based on the 30-company ranking.
Collaboration
3 pairs
co-assignee pairs identified
Co-filing is rare and mostly internal
Only three co-assignee pairs appear in this dataset, and the strongest of them links two divisions of the same corporate group. Cross-company joint filing is not a visible pattern here — most assignees are protecting their own portfolios independently.
Strongest pair recorded 4 shared filings.
Recent filing momentum by assignee
| Assignee | Recent year | YoY |
|---|---|---|
| Honeywell International Inc. | 0 | — |
| Pratt & Whitney Canada Corp | 0 | — |
| Airbus Operations GmbH | 0 | — |
| United Technologies Corp | 0 | — |
| RTX Corp | 0 | — |
| Safran Power Units | 0 | — |
| Embraer SA | 0 | — |
| Hamilton Sundstrand Corp | 0 | — |
Source: Patsnap Eureka. Assignee-level momentum. Derived from a Patsnap search on Auxiliary Power Units for Aircraft covering 2015–2026, data cut-off 2026-07-31. Counts reflect published records only and shift as new filings publish.Run this in Eureka MCP
What's Next
Where to take this
The dataset points to a mature, concentrated field with flat recent filing — the open questions are about defensibility and design-around room, not about discovering a new leader.
Run a freedom-to-operate check before finalising a design
With 83.9% of records held by the top 10 assignees, any new APU subsystem design should be checked against the leading portfolios' claims before committing to a bleed-air or starter-generator architecture.
Explore FTO workflows in EurekaMap the under-claimed subclasses against your roadmap
F02D, F23R, H02K, F02B and F01D each hold single-digit shares of the 155 records — worth a closer read if your roadmap touches engine control, combustion chamber design or starter-generator machines.
Build a white-space map in EurekaSource: Patsnap Eureka. Forward-looking reading of the same dataset. Derived from a Patsnap search on Auxiliary Power Units for Aircraft covering 2015–2026, data cut-off 2026-07-31. Counts reflect published records only and shift as new filings publish.Run this in Eureka MCP
FAQ
Common questions about APU patents
One assignee leads the ranked list with 49 of the 155 records in scope, well ahead of the fifth-placed company at 7 records. The top 5 assignees combined hold 103 records — 66.5% of the field — so filing activity is concentrated among a small set of established engine OEMs and airframe integrators rather than spread evenly across many companies. Anyone assessing this space should treat that concentration as the starting point for any competitive or freedom-to-operate analysis.
Filing peaked at 19 records in 2019 and had eased back to around 10 by the 2022 midpoint, which reads as flat to declining rather than an accelerating trend. The most recent one to two years in any patent trend are understated because publication typically lags filing by about 18 months, so the true 2025-2026 volume will likely revise upward once later filings publish. Even accounting for that lag, the overall shape does not show sustained growth since 2019.
B64D, the aircraft equipment subclass, appears in 78.1% of the 155 records, and F02C, gas-turbine plants, appears in 60.0% — together they cover most of the claim activity in this dataset. Smaller subclasses covering turbine components, aeroplane and helicopter integration, electric motors and generators, internal-combustion variants, engine control and combustion chambers each sit under 10% of records. A record can carry multiple classes, so these figures do not add to 100%, but the pattern shows claim activity is heavily weighted toward airframe integration and core turbine-plant design.
US20060218934A1, filed by Honeywell International, claims an integral firebox design that lets an APU be installed without a separate firebox enclosure, using a turbomachine intake air duct secured to an enclosure with a bleed air port running from the combustor to outside that enclosure. It is described as usable both for retrofitting existing aircraft and for new-build installations. Anyone designing an APU installation that integrates the firebox function directly into the mounting enclosure, rather than using a standalone firebox, should review this claim scope closely before finalising a layout.
Subclasses such as engine control (F02D), combustion chamber design (F23R), electric starter-generator machines (H02K), internal-combustion APU variants (F02B) and non-positive turbine components (F01D) each hold single-digit percentage shares of the 155 records, well below the dominant B64D and F02C clusters. That does not mean these areas are unpatentable or unclaimed, but the claim density is far lower than in bleed-air supply and core turbine-plant design, which is where most of the leading assignees' portfolios sit. A first filing in one of these thinner subclasses has more room to establish a distinct claim position than one competing directly in bleed-air or starter-generator architecture.
Answers are grounded in the same dataset. Derived from a Patsnap search on Auxiliary Power Units for Aircraft covering 2015–2026, data cut-off 2026-07-31. Counts reflect published records only and shift as new filings publish.Run this in Eureka MCP
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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.