Recommendations for new autopilot - M20E

[rahawk]

Hello - I'm looking for recommendations, as I consider replacing/upgrading my STEC 40 autopilot.  The current unit is 21 years old, and is starting to over correct, and is slow to adjust.  I have been told the servo's may need rebuilding.  This autopilot is a single axis, is slaved to a Garmin 430W, and I have GPSS.  It has been a great unit.

 

Here is my question:  Should I upgrade this unit, as I understand it can be upgraded to have alt hold, or invest in a new install?  And if new install, what unit would you recommend? Also, I'm in the midwest (St. Louis), any recommendations experience with avionic shops would be great..

Have included a pic of the panel for reference.  Thanks in advance for your thoughts/ideas..

[aaronk25]

Boy sure would seems that given the plane is 37years or more old that it might be the best to rebuild what you have and upgrade it if it makes sense.  Altitude hold is really nice.  I have a century 3 that is original and I spent 7K and rebuilt it and overhauled the servos.  

 

I spent some time talking with central auto pilots in OK about it and what I discovered is the new auto pilots aren't without issues either and the older ones can be more robust and not affected by static electricity like the new stuff is.  Good old capacitors and resistors.  

 

A complete new auto pilot system is 30K or so for mine, and given I wasn't gonna get my money back out of it I decided to fix and repair what I had so it perfroms flawlessly.  

 

I'd probably spring for the alt hold if I were you.

[Rwsavory]

I would repair the unit and upgrade it to alt hold. Your other option is a brand new S-tec system, which is very expensive. I don't think there are any other after-market autopilots certified for your E. You could go back to the original Brittain, but I have heard the wait time for these is quite long.

We have used Dyersburg Avionics in Caruthersville, MO. They provided good service in troubleshooting and fixing our S-tec electric trim. Nice, helpful folks there.

[Bob_Belville]

I have an STEC 50 in this E and it performs just fine. It has ALTHLD but not preselect or rate of climb/descent but the cost for those features would be prohibitive, I think.

 

I also added an STEC to Tom Nalle's 9249M ('66E) when I owned it back in the 'early '80s. As far as I know he still has it. He might give you some more anecdotal evaluation on a 30 year old install.  

[John Pleisse]

Check with Cobham. If you work with a dealer, you may be able to keep existing servos and harnesses in place and make an upgrade to a 55X or a lateral move to an Stec 30. Both are great and offer different performance. I did a 30 to 55X and kept the servos and harnesses.

 

It is to my understanding that Cobham has become completely unreasonable with their pricing and re-certification process.

[mike_elliott]

If you can be patient for a few months, Avidyne has a slick new digital AP that will use the STEC servos. The mooney STC is in the works.

Rumored 9K, plug and play with current Stec setup.

[Marauder]

For me it would be a no brainer. 21 years old is not old for an autopilot that is still being produced. I personally would have them overhaul your single axis hardware and see if you can upgrade it to a System 50 for altitude hold and precision approach capabilities. Since I am spending your money, I would upgrade it to altitude pre-select and put in a DG with heading bug if you don't already have it. Or go whole hog and put in a 60-2 or 55x!

 

Someone has already invested in the AP by adding GPSS. That is an expensive option.

 

I have a 60-2 and love it.

[Marauder]

If you can be patient for a few months, Avidyne has a slick new digital AP that will use the STEC servos. The mooney STC is in the works.

Rumored 9K, plug and play with current Stec setup.

 

I heard the same but I believe you need to be on the S-TEC 55X platform.

[Mooneyjet]

Talking with the folks at oskosh this year they said that mooney was in the work and as well it would be a plug and play to the stec systems. I would defenetivily be interested, if you ever flown behind a attitude base autopilot you be sold if your doing approaches in bumpy and very windy conditions. The avidyne will work in conjunction of the aspen, I figure it will cost me as half of what my airplane is worth, but only a quarter of a ovation or an acclaim and leave me with all the cash to fly away.

[KSMooniac]

Fixing what you have will be the least expensive/painful option, at least for now.  The servos might just need a good cleaning.  Adding altitude hold would be a great idea as well.

 

The Avidyne DFC90 autopilot sounds great, but it isn't here for Mooneys yet, and they need STEC servos for now, so you might as well get your system serviced, even if you want to upgrade down the road.  I believe the DFC90 will need an attitude input, perhaps only from an Aspen unit, so that is more cost to add to the equation.  I also read that it is plug-n-play for an STEC 55x system, so I don't know if/how you get there from another STEC system today.  

[Danb]

I had similar problems with my s-tec55x..had my servos rebuilt and the system has worked flawless then wait and see what comes up in the quickly evolving state of autopilots

[rahawk]

Wow, great response and advice!  I like the approach of fixing this unit, and adding alt hold.  Thanks for all your responses!!

 

Rob

[TWinter]

I would repair the unit and upgrade it to alt hold. Your other option is a brand new S-tec system, which is very expensive. I don't think there are any other after-market autopilots certified for your E. You could go back to the original Brittain, but I have heard the wait time for these is quite long.

We have used Dyersburg Avionics in Caruthersville, MO. They provided good service in troubleshooting and fixing our S-tec electric trim. Nice, helpful folks there.

I'll second Dyersburg Avionics in Caruthersville, MO. They did all my avionics this year including GTN750 and my S-tec 30 ALT. Jerry and his crew do very good work. I think I have probably spent enough to fund him a Branson vacation home.

[tomn]

I still have the STEC 50 in my E that Bob installed. It is still working great - I have no plans to change it and would rebuild anything that fails before replacing it with a new system. Alt hold is a must if flying long cross countries.

I have had a recent issue with it losing its alt hold ability twice - it would go up/down 100 ft each way repeatedly hunting for level. The first time was shooting ILS practice approaches in some turbulence. The second was a short local flight the next time up. The second time I recyled the unit and it started working fine, the first time I shut it off and left it off. Powered up and ran the test mode while sitting still this morning and it flew for 4 hours perfectly today. Anyone seen issue before? (Didn't mean to redirect the thread - but while I'm here...)

Tom

[KSMooniac]

Tom, next time that happens try using your alternate air.  I get that sometimes and think it is due to moisture in the static lines.

[tomn]

Scott, the first time was in the clouds. The second time was not but it was somewhat humid. Thanks for the information - I'll give that a try if it does it again. Do you have to recycle the unit at the same time or just open the alternate air and it stops?

[DrBill]

I have an STEC 30 with Alt Hold and GPSS with the 430W.  AWESOME.   I'd get your system fixed and upgraded with Alt Hold.

[M016576]

I have a 30 year ol century 41 autopilot. It wasn't working when I bought the airplane. At annual I asked a mooney MSC to repair it. They tried to talk me into. Buying a new STEC system. The quote was something like 15K. I politely refused, and had them send the A/P computer to Autopilot central. $500 bucks later, and my C41 has been rock solid for the last 3 years.... I understand the desire to upgrade, but at some point, particularly with an older model mooney (M20C-K), you might be better off selling your current plane and buying one with a new A/P in it already.,., the hit you take to install a new but basic a/p can be 40% of the value of the aircraft. I guess it's the same with all avionics, though....

[Bob_Belville]

... I understand the desire to upgrade, but at some point, particularly with an older model mooney (M20C-K), you might be better off selling your current plane and buying one with a new A/P in it already.,., the hit you take to install a new but basic a/p can be 40% of the value of the aircraft. I guess it's the same with all avionics, though....

I guess that's one way to look at it..

 

I bought 9249M (M20E) in 1977 for ~$19,000. I sold it in 1988 for ~$19,000. I flew it well over 2000 hours in all kinds of weather including 200 & 1/2 in the rain at night, inadvertent ice, and a great deal of convective junk. Early on I added a STEC50, a Stormscope, a DME and an RNAV as technology became available.

 

Did I waste my money spending far more than 100% of what the plane was worth? I guess it depends in part on what your neck is worth to you and those who depend on you.  

[Bob_Belville]

I might add I also painted the plane, redid the interior, added the cheaper speed mods (various gap seals), and replaced the engine with a factory new A1A during those 11 years before I sold it for what I paid for it. 

[Marauder]

I might add I also painted the plane, redid the interior, added the cheaper speed mods (various gap seals), and replaced the engine with a factory new A1A during those 11 years before I sold it for what I paid for it.

And your comment supports my wife's comments to me about plane owner/stewardship; "it would have been cheaper for us if you had a cocaine habit".

[BigTex]

I personally feel we are all stewards of the planes we own. We should all make sure that when we sale our aircraft it is sold in better condition that what it was when it was purchased. "Fly it Forward" for both pilots and aircraft.

[Lood]

Sorry to highjack your thread, but while on the autopilot topic, what would you guys suggest I do in my F? It has never had anything autopilot installed, except for the original Brittain PC wing leveler system, but that was removed many, many years ago.

I thought along the lines of something that I can build up over time and maybe start out with something like a wing leveler or something that can track the heading bug and then add as funds allow?

[Bob_Belville]

I personally feel we are all stewards of the planes we own. We should all make sure that when we sale our aircraft it is sold in better condition that what it was when it was purchased. "Fly it Forward" for both pilots and aircraft.

Nicely put Gary. They ain't making these wonderful flying machines anymore.

[Bob_Belville]

Sorry to highjack your thread, but while on the autopilot topic, what would you guys suggest I do in my F? It has never had anything autopilot installed, except for the original Brittain PC wing leveler system, but that was removed many, many years ago.

I thought along the lines of something that I can build up over time and maybe start out with something like a wing leveler or something that can track the heading bug and then add as funds allow?

I think your practical choices are STec and Brittain. Was everything striped out when the PC was disabled? Boy, I'd hate to have to fly a Mooney single pilot, IMC w/o a wing leveler. I would talk to the nice people in Tulsa and pick their brain. www.brittainautopilots.com/