Emissions tests on US engines and turbines are filed with EPA by retyping the test report by hand. About 1 in 4 filings we checked has a slip.

Slipschecked by hand

18 of 66 filings

A number in a different box, a date slip, settings copied from another job.

Why nowfilings a month

1,225 from 20

EPA made online filing mandatory for engines in February 2025. It's about 1,900 a month now, with turbines added in 2026.

What we doStackbook

Stackbook reads the test report and fills in EPA's form, flagging anything a reviewer would catch.

Plate I · Engine and turbine test filings sent to EPA each month Every filing listed on EPA WebFIRE, Jan 2025 to Aug 2026 (24,773 in all)

02 · Details

The slips, by filings: value in another field or form 4; process value under another parameter 4; setup value carried over from another job 3; date or time slip 3; other 6. As far as we can tell, none changed whether a unit passed.
Reading only the report PDF, Stackbook filled in 190 of the 454 values firms filed. 109 of the rest aren't in the report at all; they come from the firm's own records.
66 public filings with the report attached, one recent filing per firm plus earlier spot checks, Mar 2025 to Aug 2026. Not a random sample. No firm, site or filing is named. This is about the retyping step, not about whether anyone complied.