The ranking returned by this dataset covers seven assignees across 142 records, and it is heavily skewed toward one company, which alone accounts for 93 of the 142 records. The next four assignees combined bring the top five to 140 records, or 98.6% of the total, leaving only a small remainder for the rest of the ranking. This means due-diligence work in this space should start with the leading portfolio's claims rather than a broad market scan.

No — filings rose from 4 in 2017 to a peak of 34 in 2021, then dropped sharply, with the 2022 midpoint and the most recent year both showing no filings among the ranked leaders. Because publication typically lags filing by around eighteen months, the very last year in any dataset like this understates true activity, but the multi-year decline before that lag window is a genuine signal, not an artefact of reporting delay.

Bleed architectures draw hot, high-pressure air directly from the engine compressor stages and condition it through an air cycle machine before it reaches the cabin; bleedless (or low-pressure-bleed) architectures reduce or eliminate that draw, often substituting electric compressors, to save fuel. In this dataset, that engineering split shows up in the technology composition: F25B refrigeration and heat-pump classes account for 16.9% of the 142 records, while F02C gas-turbine classes account for 14.8%, marking where bleed-source and cooling-cycle claims diverge. A filing strategy in this field should identify which side of that split a claim sits on before checking prior art.

Class-level shares below the dominant B64D aircraft-equipment category point to thinner coverage: B01D separation processes at 8.5% of the 142 records, B01J catalysis at 7.0%, C25D electroplating/electroforming at 5.6%, and G05D non-electric variable control at only 4.2%. These lower shares suggest ozone-converter catalyst regeneration, cabin-pressure-schedule control logic, and electric-compressor thermal management are less densely claimed than the core architecture patents, making them reasonable places to start a novelty search rather than assuming the whole field is closed.

US9580180B2 describes a low-pressure bleed air aircraft ECS that operates in two modes via a by-pass valve: when the valve is open, bleed air by-passes the air cycle machine and the system runs at a lower bleed pressure, and when closed, the system runs at a higher bleed pressure, with a bleed air system controller and ECS controller selecting between high- and low-pressure engine bleed ports. It was filed by Honeywell International and published in 2017. Anyone designing a dual-pressure or by-pass-valve-based ECS should read the specific claim language on controller coupling and valve-position logic rather than assuming the concept alone is unclaimed, since the mode-switching mechanism is the likely point of overlap.