Century IIB autopilot repair

[Ultranomad]

I guess it's an autopilot repair season. Mine is neither an S-Tec nor a KAP 140 but a lowly Century IIB, and it doesn't work. The servo seems to be OK - or at least it locks the yoke when I turn it on - but neither the uncoupled nor the coupled mode produces any control input. I was hoping to fix it myself and have it signed off by the avionics engineer at my CAMO, but, according to the maintenance manual, there's very little I can do without a test set. The previous owner admitted he had never used it, and he didn't have any useful information, either; in principle, I can't exclude the possibility of misconfiguration - at least it's not a standard setup, I have a KI 525 (driven by KCS 55) in place of the directional gyro. Does anyone know a shop in the UK or continental Europe specialising in these beasts? Or maybe there's such an engineer right here?

[n5296s]

Good luck! I had a Century III (I think - it was a while ago). I spent a lot of money getting it to work when I bought the plane - it had clearly never been used for years. During its occasional working moments it did a very nice job - full three-axis, coupled approaches, etc, and pretty stable in mod turbulence. But then it started to fail again in various ways, and each time my local avionics shop would find corroded connectors etc and replace/repair them. Finally though it became unrepairable - or at least they said they'd repaired it, but when it wqent into a 1000 fpm dive at 400' on a coupled approach I decided it was time for a new one. The installed cost of the replacement STEC-30 was less than I'd spent on repairs :-(.

Honestly I would just forget it and buy a new one. It'll cost you less in the long run and it might even actually work.

[achimha]

Ultranomad,

you're only about 45 minutes away from Straubing EDMS. Avionik Straubing (http://www.avionik.de/home_e.php) is most likely the best address. Make an appointment, fly there and you'll know more. I have always received a free loaner once the faulty component was identified (in case it couldn't be repaired on the spot).

Achim

[dirkdj]

My 39 year-old autopilot (Bendix FCS810) that was declared dead by several shops, was overhauled and repaired by a shop in Edmonton, Canada. After re-installation, all pots on the computer and control panel were soaked in Corrosion-X :ok:

No more troubles since at least 10 years, works perfectly.
On these old analog autopilots, the pots going scratchy are probably 75% of the problems. Worth giving it a try. Don't allow any Corrosion-X to touch any of the clutches on the servos. Treat all connectors and pots and circuit board connectors you can get hold of.

[peterh337]

If it were just the pots going bad, changing them for modern high quality conductive plastic versions should be easy enough.

[achimha]

Equally likely are problems with the gyros the APs use as inputs. Most turn coordinators are electric and the old motors use brushes. The bearings also wear out. Coal dust gets into the pickup sensors, etc.

What you need is a shop with test equipment, diagrams of the electrical circuit and a lot of routine dealing with your very AP. In my experience, most problems can be fixed within an hour by such a shop.

[piperarcher]

I also have a Century IIB, and pleade forgive my naivety as this isnt something I have looked into much, but is it possible a) on a Piper Archer II to upgrade to one of the similar age auto-pilots that maintain altitude b) find a company that might 'upgrade' an old piece of kit to something equally old, but a bit more useful? Obviously we have the servo units and other components for horizontal movements, but wasnt sure if the kit was in place for vertical movement (servo's etc).

The group I am in is saving up for some bodywork / re-spray work so I am looking at this from am a very limited budget point of view at the moment, hence there are no options for spending thousands on more modern systems :sad:

As an aside my Century IIB, will often do a 30 deg angle of bank turn, I am sure I read that it was supposed to be limited to a rate 1 turn. Does anyone have any similar experience of this?

[Ultranomad]

piperarcher, according to the manual, Century IIB is limited to 30° bank angle when manually controlled, or 20° when in HDG mode.
Installing a different autopilot is likely to involve a design approval, which usually commands a five-figure price (unless, of course, it has already been installed on the given type in the EU).

[david viewing]

There's a very interesting blog running here (http://miscsolutions.wordpress.com/2011/02/16/troubleshooting-old-century-autopilots/).

Following a link on this blog, I downloaded the Service manual from here (http://aero-stuff.com/century-ii-iib-amp-iii-flight-systems-68s54-service-manual-1395-p-2114.html). Manuals are also available at higher prices from Essco (http://www.esscoaircraft.com/p-1548-edo-aire-century-ii-iib-iii-flight-systems-maintenance-manual.aspx).

Presumably the issue with replacing the wing leveler/heading hold kit in a Warrior with something more modern would be the mod fees. Does anyone know of a mod for this simplest of set-ups?

[wigglyamp]

All retrofit autopilots are by a validated FAA STC. S-TEC (now Cobham) have STCs for most aircraft and there are many validations from UK CAA OR German LBA as well as the later ones from EASA. If you want to install a system that has an FAA STC but isn't validated in Erope, S-Tec charge about $1200 to deal with the paperwork, which can take 6 months to get through EASA.

[AC-DC]

In the UK there is a guy whoknows these units inside out. If it is of interest let me know and i will get the details.

[piperarcher]

AC-DC - I would be interested if you could pass on the details.

Ultranomad - Thanks for your reply. I had read the same about you with regard to angle of bank, but I find that if I use the Heading mode, and turn the bug to something like 180 degrees, it rolls out onto something nearer than 30 degrees, rather than 20. Thats OK in VMC but in IMC, even on autopilot, 30 degrees could be a bit dangerous. If I am in IMC, I generally do most significant heading changes by hand flying.

PiperArcher.

[irish seaplane]

Hi,
I'm also looking to find a guru for older autopilots. I have two Cessna APs and one Century IIB that could do with TLC. I know they will never be an STec 55 but it would be nice to find out if there is someone who is expert with the older boxes.

I had heard of a Roger something in Stapleford who was supposed to be the man....

Irish

[rgsaero]

Try International Aerospace at Cranfield. They've fixed two or three for acquaintances of mine.

[wsmempson]

Have a chat to Avionicare in Southend - they're one of the few outfits who can not only work on this stuff, but are able to pull it out and bench test it themselves, as opposed to sending it to someone else. Thoroughly good guys.