Is AC23-27 applicable here? IOW was the original TC issued prior to 1/1/80?
http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_23-27.pdf
I did wonder if it came out of a seminar.
The problem with seminars on regulatory matters is that they are strongly self selecting on the personality type, and a good % of FSDO inspectors are very difficult knuckleheads (I got this expression from a senior FSDO inspector in California, BTW).
So someone doing a seminar is likely to be one of those types. Nobody “pragmatic” is going to stand up in front of an audience which may include some FAA people, describe how to read the regulations accurately, and then his past signoffs may get visited.
There was one famous case where somebody was told in such a seminar that there is NO WAY a Concorde battery can substitute for a Gill unless there is an STC. This is now widely (in the USA) regarded as bollocks. I spoke to Concorde and they agree it is not true but they still got some STCs because some people refuse to believe it.
I guess the form fit and function is a useful route to determining something is a Minor alternation, but the regs still don’t support this method. They are much more permissive.
Still, this is a route which might be useful if somebody can find a dimensional (etc) replacement for the Weldon pump, but then all IAs I have worked with would anyway agree that if the spec is the same and it fits, it is a Minor mod.
The AEA seminars are presented by Ric Peri and are often attended by FAA inspectors. The AEA are always trying to find the simplest, least regulatory solution for it’s members (most U.S. avionics shops and quite a few European ones).
Incidentally, the AC23-27 mentioned above whilst referring to vintage aircraft, pretty much confirms everything I said earlier – including the specific reference to form/fit/function.
Is there a procedure for substituting a discontinued part which grounds the aircraft?
Back to the original question: What do you mean by “procedure” and why would that so-called procedure “ground the aircraft” ?
Sorry; I meant “Is there a procedure for substituting a discontinued part whose non-availability grounds the aircraft?”
Thanks fro the clarification 
The FAA does not give a squat that you cannot find a replacement part for your acft. Not their problem.
Thankfully, there are “work arounds” as pointed out above, that are acceptable to the FAA in the vast majority of cases.
Interesting, since the “official point of view” on the Socata owners’ group is the usual 100% strict one: this is it, no approved pump, and no other options.
Of course such a situation would suit Socata, whose tacit approval and support is needed for the owners’ group to exist in its present form.
Unfortunately Socata cannot get this fuel pump either so there are no winners either way…
It might be enlightening to look at typical examples of some FAA certified types in 2016, the Globe/Temco Swift comes to mind. I wonder if there is one flying today with less 100 field approvals? 
More generically many of them have non factory engines and cowlings, non factory controls, non factory seats, non factory canopies, flush riveting, different fuel tanks, different panels and instruments, non factory landing gear hydraulics, basically non factory ummmm…. everything. The factory hasn’t existed for over 65 years, and neither have many of the component suppliers. I know one one that has a different wing section and no slots. Some of that gets done with STCs, some with Field Approvals based on old 337s (which if old enough can be used as approved data), some with new field approvals – which may take some FSDO shopping. The older and less well supported the type, the more the owners start to band together and figure out how to get things done as opposed to petty criticism of each other because somebody didn’t source their safety wire from the factory
Beyond that, if the type is old enough and also unusual enough, there is likely to be nobody with authority who knows just what was original with any great precision, and the factory documentation won’t exist to that level of detail either. Welcome to the world of the ‘antiquer’ who owns and flies an FAA certified plane. There are actually practical advantages to flying an aircraft type for which most of the axe grinders are dead or overseas. Without data upon which to make a fuss, generally for tiddly little stuff nobody in FAA Land makes a fuss unless there is reason to do so.
