Century 41 Glide Slope

[opie]

 Does anyone know anything about the GS and the century 41?  I own a 1979 M20K and took her out for a two hour IFR flight the other day to shoot some ILS and GPS approaches.  Everything worked very well in the horizontal modes (NAV and HDG) but never captured the GS when in APP mode.  the APP light never went steady and the GS light never came on.  The system just continued to fly the approach in APP mode with no vertical coupling.  The EFIS (Sandel 3308), and GNS 430W all indicated GS guidance and I just hand flew it down the GS so that is no worry.  Additionally the NAV2 VOR and CDI also indicated correctly so my assumption is the Century 41 GS logic has checked off the net.  Anyway just wondering if anyone out there has tinkered wih any of these systems and had any idea where to start looking prior to my local shop out here doing discovery learning at $80 per hour.

 

[jetdriven]

get ahold of the service manual for it and start digging.  otherwise the shop will just start replacing parts until you spend 5K or give up.  troubleshooting saves plenty of time and money.

[opie]

Thanks already on it....was hoping to lead turn the page by page read by plugging into the knowledge of the masses.  Expensive fixes tend to bite into the monthy flight time goals and wish lists like interior.

[M016576]

I had some problems with my C41 a year or two ago that sound similar to what you're experiencing.  Turned out to be a blown fuse. 

LASAR sent the autopilot computer to autopilot central (I think that's the name of the place), and they threw it on the test bench.  Turned out to be 300 or so bucks plus shipping and removal/install.  Not too bad of a fix.  The C41 couples flawlessly to GS on my 430W and ILS (KNS80) now.  Might be worth looking into... (LASAR's recommendation intially was to suck it up and buy a new A/P rather than try to troubleshoot the old one... a new STEC is 15K... I wasn't going to spring for that without at least getting the computer bench checked by an A/P specialist). 

Good luck!  When the C41 works, though, it's a thing of beauty!

[opie]

Thanks...this is exactly the type of info I was looking for.

[jax88]

Any of you Century 41 owners ever have a problem with the AP always wanting to climb?

[LANCECASPER]

Just a thought . .  I've never flown with a Centiry 41, but some autopilots won't capture the GS if when you intercept the localizer you are above the glidepath. I had a STEC 55 in a Mirage that was like that. I was used to a KFC 150 in a Bravo where it wasn't a problem.

[RJBrown]

What Lance said. The C41 in My 1980 K would only capture from below.

[RJBrown]

What Lance said. The C41 in My 1980 K would only capture from below.

[opie]

Thanks for the good gouge and affirm to all....I thought of that while airborne and did a couple of GPS approaches to make sure with same result.  On both ILS and GPS approaches I would watch the GS come down the HSI and CDI and just keep going down as drove right through waiting for the nose to pitch over.  APP would just continue to flash and GS would never illuminate.  I then had to revert to the simple but uncivilized way of piloting such a magnificent and modern machine and acually have to lay hands on the yoke and fly the acft....how barbaric.