Century 31 Autopilot Up/Down Rocket Switch Replacement?

[Austin305Rocket]

Hey Folks,

We've got a Century 31 in our Rocket and the Up/Down rocker switch is now stuck in the UP position.  You can feel it on the rocker switch that it doesn't have any 'bounce' and it's permanently stuck there.  We're toying with the idea of biting the bullet on a GFC500 (we already put dual GI275's in a few years ago) but would like a way to at least get the existing AP into a neutral state with that rocker switch so we can at least use it in cruise until we decide what the next steps are going to be.

Right now as soon as you engage the AP it wants to climb.  Our local avionics shop won't work on anything that's not digital anymore and they recommended a shop (I believe it's somewhere in TX as are we...but IIRC, it's $1000 to get them to even look at it).  Our A&P has given us the green light to see if we can either 1) replace that rocker switch or 2) get it into some kind of neutral configuration and then INOP that rocker switch until we can find a replacement part or do an avionics upgrade.

So, anyone 1) know where to find a replacement part for this thing?  It's not the actual black plastic on the outside that's broken - it's the spring or likely plastic mechanism inside that's no longer working or any help/insight on what/how else to go about getting this old ass thing back to where at least it'll do an ALT hold.  I'm having absolutely zero luck finding a PDF or online version of a service manual for this unit to see what the actual part is - if anyone has an old one of these in a box somewhere or knows someone that does, please let me know!

Thanks in advance!

Edited October 26 by Austin305Rocket

[LANCECASPER]

Paging @Jake@BevanAviation

[Jake@BevanAviation]

@Austin305Rocket Only way to get replacement parts would be someone that has old stock or from a parts unit.  My guess is something has failed in the switch assembly.  I would have to look Monday to see if I have any good parts units.  If you can bite the bullet and do the GFC500 that would be ideal.  However, if you need more time try looking on eBay for parts units.  Our minimum charge to evaluate a unit is $270.00, I will look for used parts Monday morning, if I have something I will send you a PM.

[LANCECASPER]

6 hours ago, Austin305Rocket said:

Hey Folks,
We've got a Century 31 in our Rocket and the Up/Down rocker switch is now stuck in the UP position.  You can feel it on the rocker switch that it doesn't have any 'bounce' and it's permanently stuck there.  We're toying with the idea of biting the bullet on a GFC500 (we already put dual GI275's in a few years ago) but would like a way to at least get the existing AP into a neutral state with that rocker switch so we can at least use it in cruise until we decide what the next steps are going to be.
Right now as soon as you engage the AP it wants to climb.  Our local avionics shop won't work on anything that's not digital anymore and they recommended a shop (I believe it's somewhere in TX as are we...but IIRC, it's $1000 to get them to even look at it).  Our A&P has given us the green light to see if we can either 1) replace that rocker switch or 2) get it into some kind of neutral configuration and then INOP that rocker switch until we can find a replacement part or do an avionics upgrade.
So, anyone 1) know where to find a replacement part for this thing?  It's not the actual black plastic on the outside that's broken - it's the spring or likely plastic mechanism inside that's no longer working or any help/insight on what/how else to go about getting this old ass thing back to where at least it'll do an ALT hold.  I'm having absolutely zero luck finding a PDF or online version of a service manual for this unit to see what the actual part is - if anyone has an old one of these in a box somewhere or knows someone that does, please let me know!
Thanks in advance!

 

(That's a Century 41 in your picture. The drawings below are for a Century 31.)

It would be interesting to see if the springs on those two switches that the rocker hits, just above the number 14 are still intact.

Could you just avoid the right rocker switch by climbing up to altitude manually and when you get to altitude hit HDG or NAV and the ALT?  If that worked at least you'd have the autopilot on cross country flight. Or maybe the UP switch is stuck in the ON position. If the rocker was removed, could you use it the way I mentioned?

They must not have made nearly as many Century 31s. I don't see any used C31s on eBay or at BAS Aircraft Salvage.

[Austin305Rocket]

Thank you - Yes, we do have a 31 but wasn't able to find a shop manual online and couldn't find a picture like that.  I do believe that spring mechanism in the likely culprit.  As I mentioned, you can definitely 'feel' that the springs behind the rocker switch are compromised in some way.  There's no 'bounce' when you push "up".

[PT20J]

That looks like a standard part. If you can take the unit apart and get the part number, you may be able to find them at one of the electronic component suppliers such as Digi-Key or Newark.

[N201MKTurbo]

Those slide switches get sticky over time, cleaning and lubing them would probably get them going.

 

[PT20J]

1 hour ago, N201MKTurbo said:

Those slide switches get sticky over time, cleaning and lubing them would probably get them going.

 

Not a bad idea and certainly worth a try. Use contact cleaner. WD-40 or other lubes will gum them up.