One assignee leads the ranked field with 168 of the 621 records in scope, well ahead of the next four, who together bring the top-five combined share to 84.1% of all records. This level of concentration is typical of jet-engine hardware, where a handful of OEMs have filed continuation patents across successive blade generations. Anyone assessing this space should treat the top five as the primary reference point and the remaining 37 ranked companies as a long tail of narrower, often single-process filings.

Hollow fan blade patents typically claim the internal structure and manufacturing process — most often diffusion bonding combined with superplastic forming — used to reduce blade weight while preserving strength. Wide-chord fan blade patents claim the external aerodynamic profile, a broader blade shape that improves efficiency and can itself benefit from a hollow internal structure. The two concepts are complementary in practice; many commercial fan blades combine a wide-chord profile with hollow internal construction, but the patent claims covering each aspect are usually filed and litigated separately.

The tracked trend shows filings climbing from 13 in 2017 to a peak of 27 in 2018 before settling into a steadier band in following years. The evidence available does not attribute a specific cause to that peak, and reading too much into a single year's spike is risky without matching it to specific product launch cycles at the major engine OEMs. The more reliable recent signal is the 2021-to-2024 span, where filings rose from 9 to 11 records, a 22% increase over three years not yet affected by publication lag.

US4882823A claims a specific superplastic forming and diffusion bonding process — using stop-off material to control where two or three sheets bond and where they instead deform to a contoured shape — rather than the concept of a hollow fan blade in general. A new design using a materially different joining process, sheet arrangement, or stop-off approach would sit outside its specific process claims. Any team pursuing a hollow blade via diffusion bonding should still have counsel review this filing's exact claim scope and family status before finalising a manufacturing process, since it is one of the most-cited records in this dataset.

Diffusion bonding and superplastic forming are the two process anchors built into this search, and they show up heavily inside the B23K (welding/brazing, 15.6% of the 621 records) and B21D (sheet-metal working, 15.5%) IPC classes. B23P, general metal working, is broader still at 28.0% of records. Together these process classes represent a claim space that sits apart from the aerodynamic structure claims concentrated in F01D, meaning a manufacturing-process innovation can often be claimed and defended independently of the blade geometry it produces.