Edo Air Attitude Indicator

[T. Peterson]

The AI in my 1979 231 failed and was replaced with an exchange unit in February of this year. It failed again and was again replaced with an exchange unit in October during the annual. Yesterday on our way home from Alabama it failed again. Just does a very slow roll to 20 degrees right bank. Fortunately I have a backup AV-30 which is spot on and we were for the most part vmc. No anomalies with the vacuum system of which I am aware. Just to make sure, I turned on the backup vacuum pump, but nothing changed.

 I called the overhaul facility in Wichita and they are sending a replacement to my maintainer after the new year. Do you fellas find it conceivable that two units in a row could fail like this, or might there be an issue with my airplane that could cause this?

 If this happens again I believe I will replace it with an electric AI, but will that be compatible with a Century 41 autopilot? 
I welcome your comments and advice.

[OR75]

I believe the only electric options you have would be an Aspen (up to $10k to get the config you need) or the GI-275 ADHARS with A/P and thats not much cheaper 

all these do a lot more than the basic attitude output for the A/P you are looking for .

I am hoping the AV-30C or the RC-Allen  will eventually get A/P outputs

 

 

[0TreeLemur]

A failing vacuum pump can discharge chunks of graphite back into the vacuum system.   I had this damage an AI once.   Seems unlikely though given that you didn't indicate a reduction in vacuum.  Most likely the replacement they sent you was defective.

[1980Mooney]

4 hours ago, T. Peterson said:

The AI in my 1979 231 failed and was replaced with an exchange unit in February of this year. It failed again and was again replaced with an exchange unit in October during the annual. Yesterday on our way home from Alabama it failed again. Just does a very slow roll to 20 degrees right bank. Fortunately I have a backup AV-30 which is spot on and we were for the most part vmc. No anomalies with the vacuum system of which I am aware. Just to make sure, I turned on the backup vacuum pump, but nothing changed.

 I called the overhaul facility in Wichita and they are sending a replacement to my maintainer after the new year. Do you fellas find it conceivable that two units in a row could fail like this, or might there be an issue with my airplane that could cause this?

 If this happens again I believe I will replace it with an electric AI, but will that be compatible with a Century 41 autopilot? 
I welcome your comments and advice.

 

3 hours ago, OR75 said:

I believe the only electric options you have would be an Aspen (up to $10k to get the config you need) or the GI-275 ADHARS with A/P and thats not much cheaper 

all these do a lot more than the basic attitude output for the A/P you are looking for .

I am hoping the AV-30C or the RC-Allen  will eventually get A/P outputs

I think @T. Peterson previously said he has a Century 41 autopilot.  I don't think you can drive it from the Aspens.  I have the same set up but with twin Aspens.  My shop had to retain the vacuum AI on the installation. 

Sounds to me like it is a problem with the instrument overhaul shop.

[T. Peterson]

Thanks to all of you for your input. Hopefully this 3rd AI will be the charm.

 I am willing to pay for an AI upgrade to electric, but not at the expense of also putting in a whole new autopilot. My Century 41 works perfectly. I think @1980Mooney is correct in his assessment, and if this next one fails I will just eat the cost of sending it to a different overhauler.

 I knew airplane ownership was going to be costly, but I didn’t know the aggravation factor was going to be this high. Same niggly gripes over and over again. I don’t have the skills to maintain my own airplane and I may not have the personality to own one either!!

[LANCECASPER]

13 hours ago, 1980Mooney said:

 

I think @T. Peterson previously said he has a Century 41 autopilot.  I don't think you can drive it from the Aspens.  I have the same set up but with twin Aspens.  My shop had to retain the vacuum AI on the installation. 

Sounds to me like it is a problem with the instrument overhaul shop.

For ten years now the Aspen EA-100 can be used with an Aspen PFD to drive the Century autopilot to get rid of the vacuum attitude indicator. These vacuum Indicators are getting old and even after they have been “rebuilt” they seem to be problematic. 

https://aspenavionics.com/news/ea100-digital-autopilot-interface-receives-faa-and-easa-approvals-for-centu

[1980Mooney]

1 hour ago, LANCECASPER said:

For ten years now the Aspen EA-100 can be used with an Aspen PFD to drive the Century autopilot to get rid of the vacuum attitude indicator. These vacuum Indicators are getting old and even after they have been “rebuilt” they seem to be problematic. 

https://aspenavionics.com/news/ea100-digital-autopilot-interface-receives-faa-and-easa-approvals-for-centu

Thanks. That’s great to know that there are other options now.  I see from the late 2013 announcement (below) that it was certified slightly after my Aspen install (unfortunately)

@T. Peterson Looks like it costs about $3000  

https://aspenavionics.com/news/aspens-ea100-digital-autopilot-interface-approved-to-replace-century-attitu

https://sarasotaavionics.com/avionics/ea100

[Will.iam]

On 12/28/2023 at 11:33 AM, T. Peterson said:

Thanks to all of you for your input. Hopefully this 3rd AI will be the charm.

 I am willing to pay for an AI upgrade to electric, but not at the expense of also putting in a whole new autopilot. My Century 41 works perfectly. I think @1980Mooney is correct in his assessment, and if this next one fails I will just eat the cost of sending it to a different overhauler.

 I knew airplane ownership was going to be costly, but I didn’t know the aggravation factor was going to be this high. Same niggly gripes over and over again. I don’t have the skills to maintain my own airplane and I may not have the personality to own one either!!

Torrey you didn’t go with Bob Bramble to overhaul your ADI?

here is a link to that thread. When i priced GI-275 to a IRAN by Bob Bramble and the fact that i would go from 5 power backups to 3 I stayed with the Vacuum ki-256.  Still cheaper than GI-275 upgrade but not a lot. 

 

[LANCECASPER]

31 minutes ago, Will.iam said:

Torrey you didn’t go with Bob Bramble to overhaul your ADI?

here is a link to that thread. When i priced GI-275 to a IRAN by Bob Bramble and the fact that i would go from 5 power backups to 3 I stayed with the Vacuum ki-256.  Still cheaper than GI-275 upgrade but not a lot. 

 

His Century 41 autopilot won’t work with a King KI-256

It will with a GI-275, which would be useful if he decides someday to go to a GFC500 Autopilot https://static.garmin.com/pumac/gi275_autopilot_compatibility_c.pdf

(or an Aspen with an EA-100 would work)

[T. Peterson]

A wealth of wonderful information from you gentlemen! Thank you all. I have already ordered the rebuilt EDO and Maxwell will install it while I wait. I want to FLY my airplane, not have it sit for weeks on a maintenance ramp! So I really hope this one works well. If not, I’ll then be pretty much forced to go a different route. A great take away from your discussion is that I CAN install certain electric AI’s that will drive my autopilot! If push comes to shove I am leaning strongly toward the Garmin 275.

Thanks again fellas for your time and excellent insights!

[philiplane]

Before installing the new AI, make sure the vacuum system is clean. The hose immediately attached to the attitude indicator should be removed and checked for debris & dirt. A new vacuum filter, and vacuum regulator garter filter are also needed. Dirt in the system will gum up the vanes and bearings inside the attitude indicator.

[T. Peterson]

1 hour ago, philiplane said:

Before installing the new AI, make sure the vacuum system is clean. The hose immediately attached to the attitude indicator should be removed and checked for debris & dirt. A new vacuum filter, and vacuum regulator garter filter are also needed. Dirt in the system will gum up the vanes and bearings inside the attitude indicator.

I’m at the mercy of the mechanic. Hopefully they know that, but I will make a point to remind them. I didn’t know about the filters you mention. I will ask if they were replaced. Makes me wonder if dirty air is exactly what has caused three failures in a row!

[Will.iam]

20 hours ago, T. Peterson said:

I’m at the mercy of the mechanic. Hopefully they know that, but I will make a point to remind them. I didn’t know about the filters you mention. I will ask if they were replaced. Makes me wonder if dirty air is exactly what has caused three failures in a row!

I have heard it said that if a vacuum pump fails you need to flush / clean all the tubes and replace all the filters before running the vacuum system or it will shorten the life of the adi. 

[T. Peterson]

27 minutes ago, Will.iam said:

I have heard it said that if a vacuum pump fails you need to flush / clean all the tubes and replace all the filters before running the vacuum system or it will shorten the life of the adi. 

Makes sense, but I never had a vacuum failure.

[LANCECASPER]

29 minutes ago, T. Peterson said:

Makes sense, but I never had a vacuum failure.

The previous owner might have and the tubing and filter may have been contaminated

[T. Peterson]

58 minutes ago, LANCECASPER said:

The previous owner might have and the tubing and filter may have been contaminated

Good point. I will email the shop tomorrow and query them.

[Fly Boomer]

On 12/27/2023 at 8:42 PM, T. Peterson said:

I called the overhaul facility in Wichita and they are sending a replacement to my maintainer after the new year. Do you fellas find it conceivable that two units in a row could fail like this, or might there be an issue with my airplane that could cause this?

I don't find the failures too surprising.  Which shop in Wichita?

[T. Peterson]

2 hours ago, Fly Boomer said:

I don't find the failures too surprising.  Which shop in Wichita?

I don’t want to prejudice anyone against the shop, because the fault could very well be in my airplane.

[Will.iam]

Torrey when i asked Bob how long ADI should last his response was could be 2 years or 20. He said he only had 2 ADI come back to him with early failures it happens but he said like engines, sitting not being used causes them to fail sooner. He commented that since i had an electrical backup vacuum pump that any time i was out at the hanger, run the backup pump for a min to exercise the bearings and not allow the gyro sit in the same spot for extended periods of time. Also good for the backup pump too. Something to think about if you are at your plane but not going to fly it that day.