Mooney_Driver wrote:
Some years ago, a friend of mine bought a lovely Cherokee which had a Century AP installed which was labled inop for decades. When the avionic guy went to check it, he found it working perfectly and could not find out why it had been labled inop, there was no tech log entry either. Turns out an owner 2 times grand to the current one could not figure it out so he labelled it inop just to forget all about it.
I had a similar experience once. The AP didn’t work and hadn’t worked for ages. I looked under the panel and found an unconnected cable. I plugged it in and the AP worked…
Interesting to see the expected outcome confirmed: Switzerland: 90% working. UK: 90% not working. The rest: somewhere in between. 
I wonder if it is the reaction to any sort of defect which may occurr.
Here, most people will call their radio shop to sort it out.
In other places, apparently they simply throw a sticker at it, pull the CB and forget all about it.
Maybe in Germany the probability of sticker vs getting it fixed increases with the distance to Straubing 
Sometimes, but I know of evidence to the contrary (which will never get posted, because everybody is looking after relationships). Based on my comms alone with them I would not go there. Yes they are a good company by the European standard, and with a fanatical following which alone will ensure lots of work.
The Swiss have lots of money and are ready to spend it. My best customers are in Switzerland and, guess what, Norway I wont say which significant European country I sell almost nothing to
The “legal issue” is the scarcity of European shops capable of fixing autopilots, but this has been made worse by the shops wanting to sell you a GFC500. Shops always take the easy route, work-wise and STC-wise. And most of the old guys (who learnt and understood electronics, not just wiring diagrams) have mostly retired. Actually that is an over-simplification; in the UK nearly all avionics guys are ex-RAF technicians, and most of them don’t know anything about electronics either, with the few I knew who did know, having all retired.
But the “practical issue” is that all this stuff could be fixed off the books, by any smart electronics engineer who trusts you to not try something stupid. In terms of electronics, it is quite simple. The old boxes are simple analog stuff, with the same failure modes as anything else (PCB corrosion, electrolytic capacitors drying out, etc). The “digital ones”, KFC225 and later, keep working and the peripherals (servos) burn out regularly instead, with dead simple solutions but nothing legally possible.
With the near-total reliance on companies (rather than freelancers), almost nobody in Europe has any freedom of movement.
Peter wrote:
The Swiss have lots of money and are ready to spend it.
Well this Swiss here won’t spend any money he doesn’t have to because often enough I simply don’t have it. Otherwise I’d have repainted my airplane yet and done other stuff which has to wait now also thanks to the residual cost left over by the accident. I wish the “rich Swiss money burners” stupidity would go away as much as “bad English cuisine” or stingy Scots.
But the 2 times I had to get my AP looked at, the company (who also installed it) were more than helpful resolving the issues including negotiating a warranty exchange on the AP computer even though it was out of warranty at the time. Yes, they are pricy but in the end, many who go cheap buy twice.
Basically AP repair and debugging is something most experienced companies leave to the few professionals who really know what they are talking about. I’ve heard really good references about Straubings capabilities when it comes to Ap’s, particularly legacy ones. While I’ve never worked with them so far as we have the said shop here on the field, they have a very good reputation when it comes to AP repair, amongst other stuff.
In the end, a skilled and knowledgable avionics engineer who knows these things inside out can more often help you save money others only put into training themselfs into AP’s using your airplane as a guinea pig.
Pilot_DAR wrote:
My least confidence building experience was a maintenance check flight in a Bellanca Viking (which has awesome flight controls, and is highly responsive!). I set the heading bug, selected “heading” and turned it on. The plane promptly rolled hard right, so I turned it off, and righted the plane. Hmmm… How bad is this? So I repeated, with more preparation for a loss of control this time. I selected the autopilot off rolling through 120 degrees of bank angle (who says you can’t have some fun on a maintenance check flight?). I took it back and made my report….
A very similar thing happened to me. After major avionics work, I took the aircraft for a check flight. When I turned the AP on, it hesitated for a moment, them promptly attempted to roll the aircraft inverted. (I disconnected at 45° of bank with roll rate increasing.) I tried it several times with the same result, but the direction the aircraft rolled in seemed random. My first thought was that the avionics shop had crossed the wires from the AI to the AP computer. However, after troubleshooting, the avionics guy concluded that the roll filter had failed. (You shouldn’t mess with old equipment…)
The aircraft has a Piper Autocontrol IIIB (= Century IIB) AP. Some aircraft need to have a “roll filter” installed between the AI and the AP computer. Its purpose is to modify the bank angle information so that the AP sees an increased or decreased (depending on the aircraft) roll rate. When the bank angle is stable, the roll filter does nothing.. The roll filter is designed to simply plug in “between” the connector on the AP and the cable from the AI, so the shop just removed it from the aircraft, hooked up the AI directly to the AP and it worked again!
In normal operation (HDG or NAV modes) you notice absolutely nothing unusual with the roll filter removed. But in Roll mode you can control the bank angle manually using a “turn knob”. The AP is supposed to limit the manually controlled bank angle to 30°, but when you now rapidly twist the knob to its maximum left or right position, the aircraft will momentarily roll to 40° bank before settling back at 30°. So obviously the roll filter did serve some purpose, but for all practical uses of the AP it doesn’t matter a bit that it was removed.
Time and effort…for serious single pilot IFR its a must have IMHO. My C41 works fine in all modes. When I bought the plane it had an issue with the wiring coming from the Yoke . Lots of wires for the trim, AP disconnect, CWS, GA switch…
It takes effort time and money to keep things going. Avionik Straubing is one of the few who know what they are doing with legacy A/Ps. They replaced the complete wiring from yoke to after the panel and cleaned the pitch trim servo and they have the test benches for the century APs. Reading all the issues with new GEN APs not sure if the reliability is better…….
Mooney_Driver wrote:
Some years ago, a friend of mine bought a lovely Cherokee which had a Century AP installed which was labled inop for decades. When the avionic guy went to check it, he found it working perfectly and could not find out why it had been labled inop, there was no tech log entry either. Turns out an owner 2 times grand to the current one could not figure it out so he labelled it inop just to forget all about it.
In about 2004 I bought a 1972 Triumph Spitfire. The seller said it didn’t have overdrive – a highly desirable extra – and indeed there was no overdrive switch on the gearchange knob, the control column, or the dash.
The first time I had cause to remove the transmission tunnel, I noticed a great big Laycock de Normanville overdrive unit bolted in place between the gearbox and the propshaft. At the same time as thinking that’s a bit of a bonus, I immediately thought it was obviously long-defunct and simply left in place passing direct drive back from the gearbox. Might as well just give it 12v and check, so grabbed some wire and a nice satisfying ‘clunk’ from the solenoid. Ran some more permanent wiring to a switch on the dash, took it out for a drive and it worked flawlessly – and has ever since.
My (sadly now ex) plane had a Century something-or-other when I bought it. It did everything an Stec 55 would including coupled approaches – in theory. I spent a fortune (several $1000s) trying to get it to work. It would work OK for a little while, then go back to the shop. They’d find some corroded connectors, clean them up, and all would be fine.
The last straw was when they assured me everything was fine including vertical control, which had been a problem. I flew a coupled approach and at 400 feet the autopilot decided to wake me up with a 1000 fpm dive.
I fitted an Stec 30 which gave sterling service right up to the end. It’s very simple – you have to adjust the trim yourself. But it just plain worked for nearly 20 years.
I have a Piper Autocontrol III, reliable but only in heading mode. Nav mode drifts very slowly left; loc mode unpredictable. I’m hesitant to disturb anything while it is working, but might try SIBA as recommended by By9468840 here.
USA rental: 2 with good King autopilots. French aeroclub: 0 fitted. UK syndicate: 1 inop Badin-Creuset. Does this conform to stereotype?
