The FAA has released their “sample size” AC. It can be found online here:
https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_33-13.pdf
The formal Title is FAA Advisory Circular 33-13, Sample Size Considerations for Comparative Test and Analysis for Turbine Aircraft Engine and Auxiliary Power Unit (APU), Parts Manufacturer Approval (PMA), and Third-Party Repair Parts (Sept. 16, 2026).
We invite MARPA members to review this and consider whether it has flaws that should be brought to the attention of the FAA.