In this dataset of 205 records, filings are concentrated at the top, with the leading assignee alone accounting for 42 records and the top five assignees combined holding 65.9% of all records in scope. This pattern is typical of aircraft-engine subsystems, where a handful of OEMs and their systems suppliers control most of the core architecture claims. Anyone entering this space should expect the leading portfolios to cover the fundamental gear-shaft and drive-train configurations, leaving more room in interface and failure-mode hardware than in base architecture.

Filings peaked in 2017 at 34 records and have not returned to that level since, but that is not the same as a declining field. The last full comparison window with complete data, 2021 to 2024, shows growth of +17%, rising from 6 to 7 records. Because patent publication typically lags filing by around 18 months, the apparent drop in 2025 and 2026 reflects incomplete data rather than reduced inventive activity.

Only 20.0% of the 205 records in scope carry the dedicated gearing class F16H, while 55.1% carry the gas-turbine plant class F02C and 48.3% carry the turbines/non-positive engines class F01D. This means most accessory-gearbox intellectual property is filed as part of a broader gas-turbine engine disclosure rather than as a standalone transmission patent, which affects how a search or freedom-to-operate review should be scoped: searching F16H alone would miss most of the relevant art.