Ancient avionics

this antenna was removed from the aircraft in 2021:

yep, most of electronis was Tesla. Later avionics was Mesit

Michal wrote:

Back in that times you did know that given airfield is on channel 4, the other one on 3. I assume exact frequency was a military secret.

Which would be silly, as anyone with a frequency counter (or a schematic for the radio) could find it out very quickly :-)

Peter wrote:

Apparently it was OEM installed so it can go in as a Minor Alteration into those airframes

I think in this instance it’s not an alteration, it’s installing some parts to build a optional system covered under the TC.

Peter wrote:

get the STC permission (may be impossible for an old product, and some don’t sell it at all)

I dont think you need it for something covered under the TC as long as the design data required for install is available to the installer.
Some OEM’s only list SN applicability if you pay for it, some others don’t , making it applicable to all SN’s that could optionally have carried it, regardless of whether actual production of that SN did include such SN or not. If you have access to data applicable to your aircratf under the TC, well, then you do. No [S]TC permission required. If not, then you ask the OEM and usually pay. Permission will then typically be in the form of a published SB and/or amended IPC

If the item was installed by the OEM on production aircraft and is covered by the original Type Certificate, a supplemental type certificate (STC) is not relevant. Installation requires only a logbook entry as it is a maintenance item not a modification to the approved type. No additional paperwork is necessary.

If the item has been previously installed on other aircraft as a modification by anybody (including the OEM) using a third party party STC, that entity obtained STC holder permission for an individual aircraft. The same is required for a current owner to do the same again now, and a 337 is filed. The 337 is for major repair or alteration only, and documents the existence of supporting approved data outside of the original TC, and the inspection of the installation in conformance with that supporting data.

Take your pick, I think the actual situation for a decades old aircraft is often ambiguous.

Peter wrote:

What era is this autopilot from?

1971 and following I guess. I flew with one of these on a Seneca I. I liked it, but I was the only one in that organisation who did.

It was a quite capable system and had a kind of altitude preselect via the wheel in the middle, a feature I absolutely loved and used quite often. It took a bit of adjusting and level off most of the time needed a bit of work but I liked it better than the KFC150 which did not have any altitude preselect.

One speciality which most people could or would not understand was that you had to synchronize the pitch channel before use with the help of a little window on the top left. But once you got the hang of that, it worked fine.

It was capable to do all radio coupling that most others of the time could, VOR, LOC, LOC Rev and it had a GS capture feature, which had a separate announciator light somewhere on the panel. It flew ILS approaches quite well, to the stunned surprise of two instructors who flew checkrides with me on that plane and who themselfs did not bother to find out what that little gem could actually do.

In current days, the logical thing would be to add an Aspen EFD to get GPSS via the heading mode. The only thing it can’t do and did not have was a flight director. But it was a darn sight more stable than some S-tec offerings I’ve come across. If it works well and there is a “guru” somewhere nearby who will help if needed, I would not think of getting rid of one of those in a hurry.

I found a manual for it here:
http://www.acepilot.com/sites/default/files/Piper%20Altimatic%20lll%20B-1%20Autopilot%20Manual.pdf

That Seneca I was one deal I missed out on when it got sold without my knowledge for a pittance. I would not have hesitated one minute to pick it up, despite the smallish range it was a comfortable and nice tourer which could be operated comparatively cheap for a twin. As it had Rajay manual turbos, it also was capable of holding a nice single engine altitude of about 8- to 11000 ft depending on weight and more if it came from above instead of the 3900 ft book altitude. The only thing I did not like about the Seneca I was its limited range as it did not have the LR tanks the II and following had, but had a fuel capacity of only 98 USG, which with a flow of 20-21 GPH meant a range of approximately 3 1/2 hours with roughly 160 KTAS (or more if you were really short range and used the Rajays) which made for a range of around 550 NM. It also did not have the club seating of the II and following.

It was sold to Germany and finished it’s life in Palma de Mallorca after a landing accident.