Ram Air Turbine Patents: Top Companies & Filing Trends 2026
- 82.1% of all 364 records sit with just five assignees — this is one of the more concentrated corners of aerospace emergency-power IP.
- Filings have pulled back sharply, down 83% from 2021 (12) to 2024 (2), the last year the data treats as complete.
- B64D aircraft equipment covers 63.2% of records, but actuator heating, hydraulic snubbing and gearing sub-branches carry far fewer filings.
Filing growth compares 2021 (12 records) with 2024 (2) — 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 364 records in scope (CR5), not by the ranked leaders only.
What this patent set covers
Ram air turbines exist to solve one problem: keeping hydraulic and electrical power alive on an aircraft that has lost its main engines or generators. The patent activity in this dataset clusters around the mechanics of getting a stowed turbine into the airstream reliably and quickly — deployment actuators, uplocks, pitch governors and windmilling control — alongside the auxiliary hydraulic pumps and generators the turbine ultimately drives. It sits at the intersection of aircraft equipment (B64D), gas-turbine and turbine engineering (F02C, F01D), and the electromechanical systems (F15B, H02K, F16H) that turn rotational energy into usable emergency power.
The 364 records in scope span 2015 through the middle of 2026, with the most recent year necessarily undercounted because publication typically lags filing by around 18 months.
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Filing concentration and technology mix
Two patterns stand out in this dataset: a small group of legacy aerospace suppliers holds most of the filings, and activity has cooled markedly from its 2019 peak.
A peak in 2019, a sharp pullback since
Filings ran at 20 in 2017 and peaked at 29 in 2019. Using 2021 (12) through 2024 (2) — the last year the data treats as complete — filings fell 83% over that three-year span, consistent with a field where the core deployment mechanics are already well-claimed by incumbents.
Aircraft equipment dominates, but the supporting classes matter
B64D (aircraft equipment) appears on 63.2% of the 364 records in scope, far ahead of F02C gas-turbine plants (29.7%) and F01D turbines (23.1%). Smaller but persistent classes — F15B fluid-pressure actuators (8.8%), F16H gearing (6.6%) and H02K electric motors and generators (6.6%) — mark where the electromechanical and hydraulic subsystems around the turbine are being claimed.
Shares are the percentage of the 364 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Ram Air Turbines and Emergency Power with Eureka
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Try EurekaA recent claim worth reading in full
Ram air turbine deployment actuator heater
The disclosure covers a ram air turbine deployment actuator assembly that integrates an electric heater element into the actuator housing. Warming the hydraulic fluid — including fluid held in an integrated hydraulic snubbing loop — reduces its viscosity, which the filing frames as directly cutting deployment time in cold conditions.Filed by Hamilton Sundstrand, published 2023-08-22.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US20060260323A1 | Aircraft with disengageable engine and auxiliary power unit components | 388 |
| 2 | US6467725B1 | Electrical generator an aero-engine including such a generator, and an aircraft including such a generator | 199 |
| 3 | US20160023773A1 | Hybrid electric pulsed-power propulsion system for aircraft | 163 |
| 4 | US20060137355A1 | Fan driven emergency generator | 142 |
| 5 | US7805947B2 | Aircraft with disengageable engine and auxiliary power unit components | 108 |
| 6 | US20160031564A1 | Long range electric aircraft and method of operating same | 102 |
| 7 | US4742976A | Ram air turbine and deployment mechanism | 100 |
| 8 | US20130098059A1 | Windmill operation of a gas turbine engine | 99 |
| 9 | US6023134A | Power conversion system for bi-directional conversion between hydraulic power and electrical power | 97 |
| 10 | US5398780A | Linear actuator with speed controlling brake | 96 |
Citation counts favour older filings simply because they have had more time to be cited — read them as a signal of influence within this corpus, not of current technical importance.
Each row carries its publication number; clicking a row searches Eureka by that number.
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The numbers point to a mature, incumbent-held field with a narrow set of still-active technical questions rather than a wide-open one.
Five firms hold most of the claim space
With the top five assignees accounting for 299 of 364 records, the core mechanics of turbine deployment, pitch governance and uplock release are largely spoken for. New entrants are more likely to find room in adjacent subsystems than in the deployment mechanism itself.
Activity has cooled from its 2019 high
Filings peaked at 29 in 2019 and fell to 2 by 2024, the last year the dataset treats as complete. That pattern is more consistent with a technology whose primary claim space is occupied than with one still being actively contested.
Influence concentrates in a handful of older filings
The most-cited records date back well before this dataset's window and describe foundational disengagement and generator architectures. Their high citation counts reflect age and corpus visibility as much as present-day relevance.
Filing activity is US-anchored with a strong European second tier
The United States leads receiving offices at 145 records, with Europe (EPO) at 89 and Germany, Austria, the UK and Canada making up a secondary tier. That split tracks the US and European base of the leading aerospace suppliers in this field.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to ram air turbines and emergency power, with the prior art for and against each one.
A field led by legacy aerospace suppliers
The assignee ranking returns 43 companies, and it is heavily front-loaded: a single leader holds 187 of the 364 records, with the count falling off quickly after the top handful.
One filer dominates the ranking
The leading assignee's count is more than ten times that of the tenth-placed filer, a gap consistent with a company that effectively defined the modern ram air turbine deployment mechanism and has kept filing around it since.
Co-filing is limited and mostly within one corporate family
The strongest co-assignee pair, at 17 shared records, links two related aerospace entities under common corporate ownership rather than an arm's-length partnership. Beyond that pair, joint filings are rare and mostly single instances.
Momentum has stalled across the leading filers
Every one of the six assignees tracked for recent-year momentum shows zero filings in the latest year in the data. Given the roughly 18-month publication lag, this understates true recent activity, but it still points to a field where the leaders are not pushing new claims at the pace they once did.
| Assignee | Recent year | YoY |
|---|---|---|
| Hamilton Sundstrand Corporation | 0 | — |
| Pratt & Whitney Canada Corp | 0 | — |
| Sundstrand Corporation | 0 | — |
| Rolls-Royce plc | 0 | — |
| United Technologies Corporation | 0 | — |
| Honeywell International Inc. | 0 | — |
| GE Aviation Systems LLC | 0 | — |
| General Electric Company | 0 | — |
Where to take this analysis
The dataset points to a concentrated field with a narrowing set of open questions. Turning that into a filing or freedom-to-operate decision means going claim by claim.
Map claims against the under-claimed branches
Run a targeted search across the actuator-heating, gearing and generator-integration sub-areas flagged here before assuming the core deployment mechanism is the only place to look.
Explore with Eureka →Track the leading assignees' newest filings directly
Publication lag means 2025-2026 filings from the top five are still arriving; set up ongoing monitoring rather than relying on the historical trend alone.
Set up monitoring in Eureka →Read the most-cited prior art in full
The highest-citation records define the baseline architecture this field builds on; understanding them is a prerequisite for any design-around analysis.
Open the citation table →Common questions about ram air turbine patents
One assignee holds 187 of the 364 records in this dataset, far ahead of the rest of the field. The next four ranked assignees bring the top-five combined total to 299 records, or 82.1% of all records in scope. That concentration reflects decades of continuous filing by a small group of legacy aerospace suppliers around the core deployment and generator mechanisms.
Filing activity peaked in 2019 at 29 records and has since declined; using the last three complete years, filings fell from 12 in 2021 to 2 in 2024, an 83% drop. That said, publication typically lags filing by about 18 months, so the most recent one to two years in any dataset understate real activity. The trend still points to a maturing field rather than an expanding one.
US11732698B1, assigned to Hamilton Sundstrand and published in 2023, covers a ram air turbine deployment actuator assembly with an integrated electric heater element in the actuator housing. The heater warms hydraulic fluid, including fluid in an integrated hydraulic snubbing loop, to reduce its viscosity and shorten deployment time in cold conditions. It is a narrow but concrete claim around cold-weather deployment performance, not a claim over the general deployment mechanism.
The core deployment mechanism — actuators, uplocks, pitch governors — is heavily claimed by the leading assignees and makes up the bulk of the 364 records here. Lower-density sub-areas such as actuator fluid heating, hydraulic snubbing loop design, and the gearing and generator-integration interfaces (F16H and H02K, each at 6.6% of records) show meaningfully less filing density and are worth a targeted freedom-to-operate check.
The leading assignee accounts for more than half of all records in this dataset, with Pratt & Whitney Canada and several Rolls-Royce and Honeywell-related entities also appearing in the ranked leaders. All six of the leading assignees tracked for recent-year momentum show zero filings in the latest year of data, though this is likely understated by publication lag rather than a genuine stop in R&D.
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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.