GPS for Century 41 AP

[PBones]

As some know here I am new to flying and Mooney. My 79 M20K Mooney is a solid low air frame (1900) and engine (5hrs) so I am concentrating on upgrading the avionics. I will need ADS-B and a GPS. I am already in the process of getting an Electronics  International engine monitor which is paramount for me.

I have a Century 41 Autopilot. It was overhauled and checked out by Century less than 150 hours ago according to the log book so it is in good working order.

I want to install a modern GPS that will work with the this autopilot without too much fan fare and maybe have WAAS, Radio and or ADS-B (not sure if I want to have a bundle unit but will entertain any thoughts about it).

Any recommendations are welcome. I don't mind spending money for good stuff, but that said, I want something that will give me good years of service.

 

[kortopates]

Hate to be the bearer of bad news, but i think your confidence in your Century AP is overblown. The old analog AP are very expensive to maintain. Even if it’s working fine now it won’t be that long till you’ll need to replace or overhaul a very expensive item whether it be a magnetometer, attitude indicator, servo etc. At several thousand each is why most of us ditched the older analog AP’s.
But as far as modern GPS Navigators the Garmin GTN’s must have over 90% of the market share from what i see as an instructor.
Your initial challenge will be in selecting equipment that will interface with the Century AP if you want to go to a modern digital attitude indicator and HSI, but on the Garmin side i believe the GI-275’s will work with your century AP, there are more expensive options as well.


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[Flyler]

I've done a bit of hunting on this topic as I have a 79 J with a C41.  I have only flown 3 types of autopilots, including this C41 and it is the most capable.  I am actively avoiding flying others   So my opinion is very novice, at best.

For steering, the C41 takes input from your Attitude Indicator as well as your Directional Gyro (or HSI if equipped) when in Heading mode.  In NAV mode, it uses the CDI.  So you'll need to provide it with that information.  You can do this with an Aspen or dual GI275 units.  Apparently the G5 works for the DG/Heading info but does not work as the AI, so if you wanted G5's you would need to keep the old vacuum AI.  There is a GPSS add-on you could get as well, but I'm not sure that is needed if you were to use modern gyro-less instruments.

I have a 530w GPS in my plane, and a G106 CDI.  The CDI can be driven by a NAV radio source (for VOR tracking, etc.) or it can be driven by the GPS.  The C41 adjusts for the needle deviation on the CDI.

I think for future compatibility it would be smart to use dual GI275 and a garmin GPS.  Then if your C41 ever dies, you could go the G500 autopilot route and not have wasted too much. 

[1980Mooney]

2 hours ago, PBones said:

I have a Century 41 Autopilot. It was overhauled and checked out by Century less than 150 hours ago according to the log book so it is in good working order.

 

1 hour ago, Flyler said:

I've done a bit of hunting on this topic as I have a 79 J with a C41.  I have only flown 3 types of autopilots, including this C41 and it is the most capable.  I am actively avoiding flying others   So my opinion is very novice, at best.

For steering, the C41 takes input from your Attitude Indicator as well as your Directional Gyro (or HSI if equipped) when in Heading mode.  In NAV mode, it uses the CDI.  So you'll need to provide it with that information.  You can do this with an Aspen or dual GI275 units.  Apparently the G5 works for the DG/Heading info but does not work as the AI, so if you wanted G5's you would need to keep the old vacuum AI.  There is a GPSS add-on you could get as well, but I'm not sure that is needed if you were to use modern gyro-less instruments.

I have a 530w GPS in my plane, and a G106 CDI.  The CDI can be driven by a NAV radio source (for VOR tracking, etc.) or it can be driven by the GPS.  The C41 adjusts for the needle deviation on the CDI.

I think for future compatibility it would be smart to use dual GI275 and a garmin GPS.  Then if your C41 ever dies, you could go the G500 autopilot route and not have wasted too much. 

As @kortopates highlights, getting service on any Century autopilot product if needed will be a problem.  Century Flight Systems went out of business well over a year ago.  You are lucky, and maybe one of the last, to have it overhauled by Century.

As @Flyler highlights, it is a very capable analog autopilot.  I have one also.  But if something goes wrong, there are no parts available and no one will service it.  You have to scrounge for used parts at best.  It is better replacing at that time.

Jake Bevan @Jake@BevanAviation at Bevan Aviation stated:

In 2021: century 41 auto pilot - " I don't like to work on the 41 as they are full of ribbon cables and a lot of the parts are not available any more.  The last 41 I sent to Century came back with a 9k repair estimate.  It had a failing transducer that would produce intermittent oscillations and multiple ribbon cable problems.

In 2023:  Century 41 Problems - "Unfortunately, with the current state of Century Flight Systems getting a Century 41 fully operational and reliable might be a big issue.  A lot of the parts are no longer available for this system.  Century is no longer doing repairs at the factory to my knowledge and has very limited support.  Due to this reason I stopped working on the C41 years ago and would only send the system back to the factory for repair.  The last system I sent in years ago came back with a 9K estimate for repair. 

My recommendation would be to replace it when you can for better reliability and support with a newer modern AP system like Garmin.  There still might be some shops out there trying to do bench repairs but parts will be the biggest limitation. Altitude transducer problems were not uncommon for this system."

 

[PBones]

I believe Flyier is on the right track on my thinking here. If I get a capable GPS that can operate the 41, why not? If the 41 fails, I can get a modern autopilot. This is my thinking.

I read a few posts here that say dump the 41 but why, it was gone though by Century and it works? I will be spending a lot of money this year to get the plane up to date on electronics and will need a GPS anyway so I think this is a more important upgrade right now, even if the 41 does not end up useful.

Thanks for any help

[Flyler]

I think the biggest reason is the added cost of "doing the job twice" as you might save money on labor doing it all at once.  While that might make sense at the end of the day, you may also find that you can keep the C41 going without dumping too much money into it.  It all depends on your budget and needs out of the plane.  My J has about 2500 airframe hours and reading through the logs, looks like the C41 computer was sent in for repair once, and the AI/DG more than once.  For having been around since 1979, I would say that ain't too shabby.  I don't expect to get another 50 years out of it, but if I could get 5 I would be happy.  I'm not planning on flying hard IMC with this thing.  I do plan to start IR training soon but thats really just to make me a safer VFR pilot, and maybe launch through a thin layer every once in a while.

[Schllc]

While budget is always a factor, one element seldom discussed in this context is downtime. 
Maybe I am an outlier here, but the biggest factor for me in these scenarios is time. 
I bought my plane to fly it, and to go places. Downtime makes me crazy. 
If you are planning to do major avionics work, what would be the reason to split that into two events, causing two long gaps in usage. There will also absolutely be added expense to this method. 
Yes, you may get years of service out of the old equipment.  You also, just as easily, could be rolling it back into the shop in 6 months to replace the AP. 
“Overhauling”, in the aviation world is a much abused term. 
common sense would dictate that at an overhaul, everything critical is replaced with new(ish) parts and it were to leave service as a nearly new unit. 
This is simply not the case.  I recently sent an electric AC condenser motor in for “overhaul”.  In the real world, when you overhaul an electric motor, it is rewound, the commutator changed along with bearings and brushes, and everything is made to like new condition.  My aircraft electric motor overhaul consisted of replacing the brushes, and they were the incorrect ones which further damaged the commutator, nothing else was done, not even the bearings. You would think for nearly $3k more would have been done. Such is aviation… 

Caveat Emptor

Sounds like an excellent time to replace the AP, and your parts likely have good salvage value, and along with the saved labor, you are likely to both save money and downtime.  You will also add value and safety to your platform.  
 

[EricJ]

13 hours ago, PBones said:

I believe Flyier is on the right track on my thinking here. If I get a capable GPS that can operate the 41, why not? If the 41 fails, I can get a modern autopilot. This is my thinking.

I read a few posts here that say dump the 41 but why, it was gone though by Century and it works? I will be spending a lot of money this year to get the plane up to date on electronics and will need a GPS anyway so I think this is a more important upgrade right now, even if the 41 does not end up useful.

Thanks for any help

I have (had) a Century III and it was working with my GPS.    It just got too difficult to keep it working so it will get replaced with a modern autopilot.   It may take spending money on some additional electronics to make the 41 work that will get deleted if/when you switch to a modern autopilot, but if you're okay with that then it's certainly doable.   The main thing is that it is very predictable that at some point the 41 will just become impractical to keep maintained, so it's not so much 'if' as 'when'.

 

[1980Mooney]

2 hours ago, Schllc said:

Caveat Emptor

Sounds like an excellent time to replace the AP, and your parts likely have good salvage value, and along with the saved labor, you are likely to both save money and downtime.  You will also add value and safety to your platform.  
 

Caveat Emptor

True - if you don’t mind heaping up piles of cash and setting them on fire. Four (4) years ago @Jake@BevanAviation said his shop quotes for a GFC500 installation (in this case replacing a KAP-150 in a J) were typically in the mid $20K’s. Of course prices have gone up in 4 years. 
 

And as is well known, the “value” of reduced downtime does not fully translate to added value of the plane if you have to sell. Upgrades lose about half their value immediately if you have to sell in the near future. Major engine/prop work has a better return but you will still be leaving money on the table. 
 

Such is the nature of General Aviation and old planes. 
 

 

[Schllc]

9 minutes ago, 1980Mooney said:

True - if you don’t mind heaping up piles of cash and setting them on fire

That is awfully reductionist, and more than a little antagonistic.
If you were so eager to spare your cash from the fire you wouldn’t own a plane. 
Everything in aviation is a trade off. I don’t pay for an airplane to sit in a hangar, I bought one to fly and that is my trade off. 

[1980Mooney]

3 hours ago, Schllc said:

That is awfully reductionist, and more than a little antagonistic.
If you were so eager to spare your cash from the fire you wouldn’t own a plane. 
Everything in aviation is a trade off. I don’t pay for an airplane to sit in a hangar, I bought one to fly and that is my trade off. 

Not trying to antagonize you but if you are giving advice on spend vs "value" you might want to let this new 231 owner that it is from the perspective of someone who owns and maintains both an Acclaim and a pressurized twin Aerostar 601P.  Yes owning any plane is a process of setting piles of money on fire - some need smaller, some need larger (or really, really larger).  Your perspective/comfort level is about an order of magnitude higher than most "cheap bastard" Mooney owners trying to support budgets for their 35-60 year old planes. It is not a criticism - your vantage point is enviable.  It is just a perspective on value.  There are many owners here that have no problem and rave about the "perceived value" of dropping $100K on glass panel/avionics upgrades.  

[Schllc]

2 minutes ago, 1980Mooney said:

Not trying to antagonize you but if you are giving advice on spend vs "value" you might want to let this new 231 owner that it is from the perspective of someone who owns and maintains both an Acclaim and a pressurized twin Aerostar 601P.  Yes owning any plane is a process of setting piles of money on fire - some need smaller, some need larger (or really, really larger).  Your perspective/comfort level is about an order of magnitude higher than most "cheap bastard" Mooney owners trying to support budgets for their 35-60 year old planes. It is not a criticism - your vantage point is enviable.  It is just a perspective on value.  There are many owners here that have no problem and rave about the "perceived value" of dropping $100K on glass panel/avionics upgrades.  

I’m not providing advice.  I’m probably not qualified to “advise” anyone. 
But, hearing a different perspective to make sure it’s considered from all angles is useful.   We all have a tendency to focus a bit narrowly when looking at these things.
This is why you post the question on a forum for random people to opine. 
Frankly, what I spend is irrelevant.  The OP’s budget and tolerance for cost and downtime has nothing to do with me. 
Owning an airplane is not a cheap endeavor, even for the cheap bastards.   If it is cheap, chances are you’re doing it wrong. 
Opening up a panel to install new avionics is both expensive and time consuming. If you spend half the amount repairing and configuring a legacy autopilot with new avionics is not free. It would be easy to spend half of the 20k cost for a gfc500. 
A good analogy would be doing an IRAN on an engine which is at TBO. 
Sure it’s cheaper but is it the cheapest in the long run?  Does it add value?

If the only question anyone has about maintenance/upgrades on an airplane is what it costs, they probably can’t afford to own it. 
 

[AndreiC]

Let me give another, more CB perspective. My previous plane, a Piper Cherokee, had no autopilot. I discovered that a version of the Century IIB was part of the Type Certificate, so I would not need an STC to install it. I found the parts for one on ebay. My avionics shop tested the head unit for free, I sent the servo to be overhauled by Autopilots Central in Tulsa, and had it installed. Total cost, about 8 years ago, was $5k all in. Despite the bad rap, that autopilot worked perfectly for the next five years with zero maintenance, and I am pretty sure it works fine still.

My main concern would be that I don’t know how much more complicated the C41 is. If it is a delicate piece of equipment with many things that could go wrong, then yes, probably keeping it in service another 10 years is a stretch. But for the CIIB the only things that were usually going bad were the connectors (still available) and the servo (which at the time could still be overhauled). If the situation is similar with the C41, installing a GPS to drive it, with the idea that if the C41 fails down the road there is a path to upgrading to a GFC500, does not sound to me like a bad idea. 

[wombat]

@PBones

I would recommend the GTN 650xi.   It's as good of a deal as you're going to get for a GPS that will stand the test of time and provide you a good usefulness while you own the plane and a good ROI when you sell the plane.  It'll work with your current autopilot either directly or through your current avionics.   You can install a remote transponder for it that will get you both ADS-B in and out.   Right now light GA is in the era where "Nobody ever got fired for buying IBM" with Garmin.   And the 650xi is the 'standard' for a somewhat-budget panel GPS.  With the integrated NAV and COM radios, it's a very handy little package.

My recommendation as an alternate solution is a 750xi.  It has some advantages that you might find worth the additional cost.   #1: You can install a remote intercom/audio panel as well as the remote transponder.  #2: The larger screen also allows more than just a larger moving map, you can show more data and options on the screen at once than you can on the 650.  #3: Larger moving map is better.  Also, the lists of waypoints visible on the list is larger so it's easier to see where you are going further out in flight plan mode.

 

I hear what the others are saying about replacing the autopilot, but if it works for now, it works.    As long as you understand that a 'recent' thorough look-over of the autopilot provides no guarantee that it won't fail next time you use it and you are ready to deal with that.  But that's true for everything.  The engine.   Landing gear.   Your own health.  

[PBones]

Thanks Wombat for clarifying my situation, what you propose is exactly what I was looking for, I did not want to stir up a "money pit if you want to fly" thread here since "If God wanted man to fly . . . .hey would have given him. . . . .MORE MONEY!

My autopilot was serviced and tested 100 hours ago, when the plane was ferried 6 months ago, it worked. I need a modern GPS to interface to it now, but be capable of hooking up to a new autopilot in the future. 

[Jake@BevanAviation]

@PBones  my suggestion would be the GTN Xi series navigators, depending on the budget will govern the size (750Xi is more expensive vs 650Xi).  I would also try and pair the dual GI275's (ADI and HSI).  The only reason I am suggesting this is looking towards the future and knowing the existing autopilot will fail at some point.  This would at least set you up for an easier transition to a Garmin autopilot.  You would already have everything the GFC500 wants.  Also, if you choose a GTN Xi unit you will have the capabilities of Smart Glide for the GFC500 once it is installed.

The Garmin GTX 335/345 transponders would be ideal when pairing with the GTN.  Panel space will govern if you need the remote mount unit or not.  Just make sure whoever the installing shop is knows how to interconnect the Century 41 system.  Garmin does a pretty good job of providing an interconnect of the new unit to a legacy autopilot system.  However, a lot of the interconnecting depends on the technician doing the job and how they interpret the prints.

Last week I helped a very well-known shop in Florida troubleshoot issues with a Century 41 system.  Thankfully it was an interconnecting issue and not a box-related problem.  Shops that have the knowledge to support this system are rapidly dimensioning over time.  That is great that the system got a clean bill of health recently.  However, I would plan on saving some money for when the system fails.  Who knows what support for Century 41 will look like then.