Hi Ron,
I understand there is no STC required, the new ones leave the factory with oil coolers, but are different engines than mine. I have a 0235-C1 in my 7ECA, I think they have K2C in the new ones, not totally sure. The 337 has to go through the FAA to get approval, a mechanic cannot just sign it. Do you know what data your mechanic used to send to the FAA, or who your mechanic used at the FAA? Thanks.
Mike