The Mark-12s are going to be a problem. If you are talking about the original
vacuum tube design (12, 12A, and 12B) with the monster power supply sitting back
aft of the hatrack in the empennage, they are FCC illegal last time I looked
(*).

As a practical matter, the 12s have a few critical parts that are absolutely
unobtainable any more...the little Nuvistor with the plate cap in the crystal
oscillator springs to mind. The crystals are damn near 50 years old and are a
bit aged. The point being is that you will be happy with those radios just long
enough to get the airplane home.

OTOH, if they are the 12D solid state replacement radios, you will be happy with
them for quite a while.

As to the airframe, the ADs are few and relatively inexpensive to comply with.
The most expensive one that comes to mind was the nose gear fork that should
have been replaced twenty+ years ago or better.

If you have a friendly IA with the computer disk, ask them to run you a computer
printout of the AD list...they will need to know what mags are on the unit,
which prop, which carburetor, etc..

If you DON'T have a friendly IA, I will run you a list and give it to you in
pdf IF you can supply me the accessories list as above. I'd also ask the owner
for the current equipment list, check it against the current weight/balance,
then look to see what is on the airplane that isn't on the equipment list.

Jim

(*) The 12s are FCC illegal, *not* FAA illegal. The practical side of it says
that you can fly with them and use them into the NEXT millenium before you will
come up against an FCC cop. They've got better things to do like chase bandit
broadcasters and the like than mess with a radio that is a few kHz. off
frequency. -- jw




(Malcolm Teas)
shared these priceless pearls of wisdom:

-Ok, so this isn't quite a fabric wing bush plane I was talking about
-before, but it looks to be a good IFR platform, and it's seems in good
-condition so far. Yeah, it's like Dad's stationwagon, but 172s are
-good well-known planes too. We're going up this weekend to take a
-look up close and see what we think.
-
-Anything special to look out for on the 172G model? It's got the flat
-six O-300 engine with an auto gas STC and Mk 12 radios.
-
-Thanks,
--Malcolm Teas

Jim Weir (A&P/IA, CFI, & other good alphabet soup)
VP Eng RST Pres. Cyberchapter EAA Tech. Counselor
http://www.rst-engr.com