I doubt there is any form of ABS filament with such a low glass transition temperature. As the original poster said, it was probably PLA.

I find it odd that the report didn't name the manufacturer of the part, and that the part was not listed on the LAA modification form. There can't be many people selling such parts at airshows, so you'd think the investigators would have been able to find out who made it.

Now I wonder if the previous owner (who installed the new fuel system) printed the part himself, then claimed he bought it overseas to avoid blame.