BTW, he said the engine is still certified even though it was hanging on the nose of a -9A.
I can see that if someone wants to keep their engine certificated for later resale value or something, but what if they didn't care about that?
The person who said the engine is "still certified" is incorrect. Any engine operated on an airframe under the authority of an experimental airworthiness certificate is an experimental engine regardless of what the data plate says. While there is no specific document that states this in plain English it is not hard to understand. Here's the reasoning behind it.
Aircraft maintenance (including maintenance of all installed components) is covered by 14 CFR Part 43, which starts out with 43.1,
Applicability. Section (b)(1) of this regulation is pertinent to this discussion. It says;
(b) This part does not apply to?
(1) Any aircraft for which the FAA has issued an experimental certificate, unless the FAA has previously issued a different kind of airworthiness certificate for that aircraft;
Since our amateur-built aircraft have never held any type of airworthiness certificate other than experimental, this section tells us the the whole of Part 43 does not apply. This means that, except as called out in the operating limitations issued to the individual aircraft by the FAA (in this case, the condition inspection requirements)
anyone can perform maintenance, repair or alterations on these aircraft, regardless of that persons certification (or lack of same) by the FAA. You do not need to be an A&P mechanic, you do not need to be the builder, you do not need to hold an FAA certificate of any kind.
Further, the requirements called out in Part 43 regarding logging of maintenance do not apply either, so (again other than as required by the operating limitations) no maintenance is required to be logged. (Best practices suggest proper maintenance records, but the regulations do not require same.)
So, if you have an engine that can be maintained and repaired by people who are not required to hold an FAA certificate, and that maintenance or repair is not required to be recorded in the aircraft records, how can the engine possibly maintain its "certified" status? Even if the logs
appear to show that all maintenance was carried out in accordance with part 43 there's no way to prove that it has. So even if you WANT to keep the engine "certified" you can't do it. Part 43 doesn't apply, so any guarantees provided by part 43 don't apply either. The engine is experimental no matter what.
With all this in mind, how can it be unacceptable to change the data plate? Or to make modifications as desired? How can an STC apply to a component that is not in compliance with a type certificate to begin with???
The bottom line; These inspectors are all wet. The engine is experimental and that's that.