EDO Attitude Indicator

[T. Peterson]

I have a 1979 M20K. The AI is an Edo-Aire Part #52D177. In the last two years I have had it replaced 3x. The third one is now slow to erect and begins to precess in flight. In straight and level flight it will slowly move to indicate 20 degrees nose down and back up to 10 degrees nose up. 
There is no indication of vacuum failure and engaging the back up vacuum pump does nothing. I have considered replacing it with a GI 275, but there is no point to do that without also replacing the DG with a 275 and getting rid of the vacuum system altogether. That is a 21000.00 bill, and with a 56000.00 engine plus all the peripherals coming in 3 weeks it’s just more than I can spend right now.

Therefore I need a replacement vacuum AI that actually works, or have mine overhauled by someone that actually knows how!!

If you folks on the forum have a recommendation, I am eager to hear it.

 Thank you,

Torrey

[KSMooniac]

You might call Century Instrument in Wichita for a consult.  I recently tried to get an Edo Aire airspeed indicator repaired with them and learned that they're essentially not supported any longer.  I don't know if the AI is any better off.  They have a TON of inventory, though, and might be able to exchange or repair yours.

Another vendor local to me is Aircraft Quality Instruments.  They did my DG a couple of years ago and it has been fine.  

[T. Peterson]

2 hours ago, KSMooniac said:

You might call Century Instrument in Wichita for a consult.  I recently tried to get an Edo Aire airspeed indicator repaired with them and learned that they're essentially not supported any longer.  I don't know if the AI is any better off.  They have a TON of inventory, though, and might be able to exchange or repair yours.

Another vendor local to me is Aircraft Quality Instruments.  They did my DG a couple of years ago and it has been fine.  

I called Century and they claim the part number of my AI is incorrect for my Century 41 auto pilot. My AI is 52D177 which they say is matched for a Century 4 auto pilot. The correct AI part number for my application is 52D267 which fortunately they do have in stock, but they think there is a slight difference in pins. So if mine is wrong, how can it fit??? Century is suggesting that maybe I don’t actually have a Century 41, but a Century 4. They want me to check, so I need to make a trip to the airport and verify. They also suggested that if I do indeed have a Century 41, that might explain why my attitude indicators are malfunctioning so quickly.

 

 

[KSMooniac]

They may be on to something.  Professional or not, no mechanic or shop will ever care as much as you do (or should!) about what is going on with your plane.  It seems natural to me since I'm very, very heavy DIY with my plane so I know essentially every square inch of the airframe, and almost every bit behind my panel.  I know that is not true of most owners, though.  My plane had it's original Century II (I believe) removed by a previous owner for an STEC 30 installation, so I don't have any direct experience with Century bits.  To get to the bottom of your mystery, you can look at your records, POH supplement(s), etc. and see what is documented.  Then you can try to read actual part numbers from various other bits in the plane, and/or match up pictures for Century IV vs. 41 from the internet and make sure you know exactly what is installed.  You can do all of this for free with just a bit of effort and not pay a pro that may not really know everything. 

[T. Peterson]

58 minutes ago, KSMooniac said:

They may be on to something.  Professional or not, no mechanic or shop will ever care as much as you do (or should!) about what is going on with your plane.  It seems natural to me since I'm very, very heavy DIY with my plane so I know essentially every square inch of the airframe, and almost every bit behind my panel.  I know that is not true of most owners, though.  My plane had it's original Century II (I believe) removed by a previous owner for an STEC 30 installation, so I don't have any direct experience with Century bits.  To get to the bottom of your mystery, you can look at your records, POH supplement(s), etc. and see what is documented.  Then you can try to read actual part numbers from various other bits in the plane, and/or match up pictures for Century IV vs. 41 from the internet and make sure you know exactly what is installed.  You can do all of this for free with just a bit of effort and not pay a pro that may not really know everything. 

My autopilot is the Century 41. Because I am currently out of state taking care of my mother, I don’t have access right now to either my plane or the logbooks, but internet pictures confirm what I already knew.

[1980Mooney]

8 hours ago, T. Peterson said:

I called Century and they claim the part number of my AI is incorrect for my Century 41 auto pilot. My AI is 52D177 which they say is matched for a Century 4 auto pilot. The correct AI part number for my application is 52D267 which fortunately they do have in stock, but they think there is a slight difference in pins. So if mine is wrong, how can it fit??? Century is suggesting that maybe I don’t actually have a Century 41, but a Century 4. They want me to check, so I need to make a trip to the airport and verify. They also suggested that if I do indeed have a Century 41, that might explain why my attitude indicators are malfunctioning so quickly.

 

6 hours ago, T. Peterson said:

My autopilot is the Century 41. Because I am currently out of state taking care of my mother, I don’t have access right now to either my plane or the logbooks, but internet pictures confirm what I already knew.

The Century 41 Autopilot was a common factory installation on both J's and K's at the end of the '70's and the early '80's.  I have a Century 41 on a beginning of year 1980 M20J.  Our planes came off the assembly line a few months apart.  Back in Nov. 2023 you commented on MS that you had a Century 41 autopilot so that matches up with your recollection.

If you currently have a 52D177, then you have the vacuum operated 2 Cue Flight Director.  Contrary to Century Instruments (Wichita) assertion, the 52D177 is an approved Attitude Indicator to drive your Century 41.  The 52D67 is an unlighted basic Attitude Indicator.

You need to talk to your avionics shop before ditching your Flight Director.   It should be a perfect unit to drive the Century 41.  Having a Flight Director is not the cause of your problems.  I think it is due to the quality of the ones that have been sold to you.  Yes the basic AI 52D267 will work but you will lose your FD cues.

From the Century 41 Installation Manual.

Edited January 17 by 1980Mooney

[T. Peterson]

10 hours ago, 1980Mooney said:

 

The Century 41 Autopilot was a common factory installation on both J's and K's at the end of the '70's and the early '80's.  I have a Century 41 on a beginning of year 1980 M20J.  Our planes came off the assembly line a few months apart.  Back in Nov. 2023 you commented on MS that you had a Century 41 autopilot so that matches up with your recollection.

If you currently have a 52D177, then you have the vacuum operated 2 Cue Flight Director.  Contrary to Century Instruments (Wichita) assertion, the 52D177 is an approved Attitude Indicator to drive your Century 41.  The 52D67 is an unlighted basic Attitude Indicator.

You need to talk to your avionics shop before ditching your Flight Director.   It should be a perfect unit to drive the Century 41.  Having a Flight Director is not the cause of your problems.  I think it is due to the quality of the ones that have been sold to you.  Yes the basic AI 52D267 will work but you will lose your FD cues.

From the Century 41 Installation Manual.

Thank you so very much! That eliminates one concern. Now I just have to find a replacement or someone that will overhaul mine. Century Instruments in Wichita doesn’t handle the 52D177 anymore and I am very hesitant to go back to the other place as all 3 of the faulty replacements came from them.

 I will continue to work this problem through a couple of other avenues and post my final results. Your tracking down the fact that my AI is not an incorrect application is an immense contribution! Thank you!

[EricJ]

A 275 for just the AI spot is not a bad option.   I had replaced a failed DG with a G5, and then replaced the AI with a second G5 later and then deleted the vacuum system.   It might be easier and less expensive in the long run than continuing to deal with the 52D177.

 

[T. Peterson]

25 minutes ago, EricJ said:

A 275 for just the AI spot is not a bad option.   I had replaced a failed DG with a G5, and then replaced the AI with a second G5 later and then deleted the vacuum system.   It might be easier and less expensive in the long run than continuing to deal with the 52D177.

 

It is a very good option, but in the short run it is thousands of dollars versus hundreds. In the long run probably a much better investment, but unfortunately I am dealing with short run dollars!

 

[T. Peterson]

I believe I have found a very satisfactory solution thanks to @Will.iam. He recommended Bob Bramble at aerolabaviation.com. I just had a very nice conversation with Mr. Bramble and I will send him my AI as soon as I can.

 

[KSMooniac]

Bob is very good!  I didn't realize he was still working, or that he will work on Century components.  He is a whiz with the legacy King gyros for those still keeping those systems going.  He'll take very good care of you.

[laytonl]

Bob bramble is excellent.  Another source - if he is still around - is Tim Brouwer at mayday avionics.  tbrouwer@maydayavionics.com.  He repaired a similar unit for me on my previous Mooney. Lee

[T. Peterson]

2 hours ago, KSMooniac said:

Bob is very good!  I didn't realize he was still working, or that he will work on Century components.  He is a whiz with the legacy King gyros for those still keeping those systems going.  He'll take very good care of you.

Bob said that he very much enjoys the work and will continue to do it as long as he is able. 

He has also moved to McKenzie, TN, which is midway between Nashville and Memphis.

He has worked on many EDO-Aire units and had no hesitation about mine. He did say that it would be a two week turnaround due the rotor of the Edo. I think he can turn around the Kings in a couple of days. In aviation terms, two weeks is the speed of light! Especially when it involves avionics. I’m delighted!