Vacuum pump failure

[Tx_Aggie]

While shooting approaches vfr this weekend, my autopilot stopped working while my backup ai started rotating all over the place and eventually went near upside down. I used the manual trim to help stabilize my approach and land where I found my vacuum pump failed. A precise flight standby vacuum pump was installed a few years ago according to the logs (1988) and neither worked while troubleshooting on the ground. 

My set up is an Aspen 1000 pro, gnc-355, century 4 autopilot which appears to be controlled by the backup AI and not the Aspen - figured that out this weekend! 1980 M20J. 

I’m interested in considering chunking my vacuum system altogether but have been told the vac pump repair will only be about $500 to repair, which is also enticing. Does anyone know if a G5 is compatible as a backup AI for the Century 41 AP? I appreciate it!

Edited December 30, 2020 by Tx_Aggie

[carusoam]

TX A,

Did you see the classic warnings?   HSI goes one way, while the AI goes the other...

Of course... if the AP is following the TC, you may only see the AI slowing down before going nuts...
 

Vac pumps are cheap...

500hrs and out... the usual time for tossing them if flying In IMC...

 

What version of the Precise flight do you have?

There is one that has deadly consequences if you are unfamiliar with its operation...

There is one that is a vac pump with an electric motor attached in the tail...

The electric motor one gets tested every pre-flight...

The other one is simple plumbing that only works with enough MP... and following the instructions...

Got a pic? I think you have the plumbing version and need to be a bit more familiar with it to have it be useful...

Find Marauder... he documented the how to use it for his M20F... before tossing it out...

PP thoughts only, not a mechanic or CFI...

Some things were good, back in the day... but have outlived their usefulness...

Best regards,

-a-

[jlunseth]

It is not a simple as you think to just dump the vacuum. Do you have a backup alternator? If not, then your all new electronics have a single mode of failure, and when failed you will lose everything on the panel. You will be less safe than your current setup of two vacuum pumps. I am trying to do the same as you, but the first step is to find a way to install a second alternator. Battery backups don't sway me. For one thing, in real life when a failure occurs you will generally find that the actual life of the backup is about half what it was rated for, especially if the failure happens 500 hours or so and several years after the backup was installed (that is about the life of a vacuum pump). If you use your aircraft for long distance travel, like me, then a half hour or hour rated backup are not enough, you need to consider the time required, in the middle of nowhere, to fly to an airport which may not be right under the wing, then descend and fly at least one approach without the AP. And don't expect you will get any help from the aircraft battery, when it is not new any more you will be lucky to get a half hour out of it, and that is with most of your panel shut down. You will also have to be vigilant and replace the aircraft battery every two or three years because it is your life line. Have to save juice for gear deployment or put the gear down and fly that way to get to your "out".

Vacuum pumps last no more than 500 hours. My suggestion is that you either add a backup alternator if that is even possible, and then spend the money on hew electronics such as the GI 275, or you  automatically replace your pumps every 500 hours no matter how well they are working. Having more than a single mode of failure driving your AI, and having a backup AI, are just a must if you fly in IMC.

[takair]

9 hours ago, Tx_Aggie said:

While shooting approaches vfr this weekend, my autopilot stopped working while my backup ai started rotating all over the place and eventually went near upside down. I used the manual trim to help stabilize my approach and land where I found my vacuum pump failed. A precise flight standby vacuum pump was installed a few years ago according to the logs (1988) and neither worked while troubleshooting on the ground. 

My set up is an Aspen 1000 pro, gnc-355, century 4 autopilot which appears to be controlled by the backup AI and not the Aspen - figured that out this weekend! 1980 M20J. 

I’m interested in considering chunking my vacuum system altogether but have been told the vac pump repair will only be about $500 to repair, which is also enticing. Does anyone know if a G5 is compatible as a backup AI for the Century 4 AP? I appreciate it!

Do you have a standby vacuum pump or a standby vacuum system?  The common Precise Flight standby vacuum system uses vacuum from the intake manifold.  It has a pull cable to move a valve. I suspect that this is what you have. There are very specific instructions on how it operates, the engine running at a low manifold pressure is key.  Typically there is a cheat sheet placard that was filled out on a test flight.  If it is truly a pump, as others have said, it should be in back and easy to troubleshoot.

[skykrawler]

My 1982 J has a vacuum failure light on the annunciator panel. There is also a gauge.  My recent pump failure (also on a +30 year old pump!) was detected before the gyro spun down and the KAP-150 AP disconnected.  The failure was not the vanes in the pump, it was the frangible plastic coupler in the drive.  Had a recent oil seal replacement on the acc drive shaft.

I previously removed the Precise Flight standby (manifold) to eliminate the AD hassle and installed a G5 for a proper secondary.   It important to know the systems on your particular airplane - how else can you understand the consequences of failures?

 

[jlunseth]

The one thing to watch out for in that failure mode, is that you need to stop using the AI as soon as the failure is annunciated. The gyro continues to spin for some time and you think you can get away with using the AI for awhile, but it starts to slowly slide off in one direction before it tumbles completely. If you continue using it you will get yourself in a graveyard spiral, or a climb or descent when you think you are level.

[Raymond J1]

 

In the Classic Vacuum Pump, the first failure is the sealing gasket (white part in the photo). In practice, this corresponds to a long time to obtain the desired vacuum pressure, the AI takes time to place itself in a horizontal position on the ground. If this piece is not changed, then it degrades even more and we come to the breakdown of the hooking. The splendor of the photo of an 800 hours.

[kortopates]

13 hours ago, Tx_Aggie said:

While shooting approaches vfr this weekend, my autopilot stopped working while my backup ai started rotating all over the place and eventually went near upside down. I used the manual trim to help stabilize my approach and land where I found my vacuum pump failed. A precise flight standby vacuum pump was installed a few years ago according to the logs (1988) and neither worked while troubleshooting on the ground. 

My set up is an Aspen 1000 pro, gnc-355, century 4 autopilot which appears to be controlled by the backup AI and not the Aspen - figured that out this weekend! 1980 M20J. 

I’m interested in considering chunking my vacuum system altogether but have been told the vac pump repair will only be about $500 to repair, which is also enticing. Does anyone know if a G5 is compatible as a backup AI for the Century 4 AP? I appreciate it!

The real problem you seem to be getting is that your Aspen was likely installed without using the Aspen EA100 AP adapter that would allow controlling your AP from the Aspen. Purely a significant  cost saving measure that eliminated the need to buy/install and wire up your AP so that original costly to maintain Century AI could be retired - instead it was just likely moved out of the way. But your "Backup AI" is actually your Primary AI since its the Century AI that drives your AP. The Aspen is really the backup. There are other options to get rid of the vacuum dependency but you probably should decide first if you like the Aspen system and want to integrate your AP in with your Aspen or go another route entirely.  if you stick with the Aspen, my personal choice would be to first update your Aspen Pro to the Aspen Pro Max to eliminate the vulnerability of bringing down the entire Aspen due to an iced pitot tube with failed pitot heat at cost of 5.5K then also add the EA100 adapter for about 3K and lastly add a real backup AI like a Garmin G5. Or you could just replace your vacuum pump and move on with a new appreciation of the your system installation vulnerabilities.  

[Skates97]

34 minutes ago, jlunseth said:

The one thing to watch out for in that failure mode, is that you need to stop using the AI as soon as the failure is annunciated. The gyro continues to spin for some time and you think you can get away with using the AI for awhile, but it starts to slowly slide off in one direction before it tumbles completely. If you continue using it you will get yourself in a graveyard spiral, or a climb or descent when you think you are level.

This is a great point.

Back in August I had my vacuum pump fail. I noticed the vacuum gage had gone to zero. I had just installed a RCA 2601-3 backup AI in place of the turn coordinator so watched both just to see how the vacuum one would progress. It was a very slow lean for quite a few minutes, I wish I would have timed it from the point that I saw the vacuum gage go to zero and when it finally fell off and started tumbling. I'm going to say it was somewhere around five minutes. The drift was so slow that without having the other AI and if I was IMC and I didn't notice the vacuum gage I would have been in serious trouble. The vacuum DG also took a long time before it started spinning, and while it began to precess faster and faster it was initially very slow.

[dzeleski]

4 hours ago, jlunseth said:

It is not a simple as you think to just dump the vacuum. Do you have a backup alternator? If not, then your all new electronics have a single mode of failure, and when failed you will lose everything on the panel. You will be less safe than your current setup of two vacuum pumps. I am trying to do the same as you, but the first step is to find a way to install a second alternator. Battery backups don't sway me. For one thing, in real life when a failure occurs you will generally find that the actual life of the backup is about half what it was rated for, especially if the failure happens 500 hours or so and several years after the backup was installed (that is about the life of a vacuum pump). If you use your aircraft for long distance travel, like me, then a half hour or hour rated backup are not enough, you need to consider the time required, in the middle of nowhere, to fly to an airport which may not be right under the wing, then descend and fly at least one approach without the AP. And don't expect you will get any help from the aircraft battery, when it is not new any more you will be lucky to get a half hour out of it, and that is with most of your panel shut down. You will also have to be vigilant and replace the aircraft battery every two or three years because it is your life line. Have to save juice for gear deployment or put the gear down and fly that way to get to your "out".

Vacuum pumps last no more than 500 hours. My suggestion is that you either add a backup alternator if that is even possible, and then spend the money on hew electronics such as the GI 275, or you  automatically replace your pumps every 500 hours no matter how well they are working. Having more than a single mode of failure driving your AI, and having a backup AI, are just a must if you fly in IMC.

 

You cant fit a second alternator in a J as far as I am aware. This is part of the reason I went with Garmin instead of Aspen. 2 hours wasnt enough for me personally. My G5s genuinely last about 4 hours, ive tested it. I would not expect the time to degrade much over 5 years because 100% charge displayed is not actually 100% charged, its most likely around 80%. This allows the battery to keep a consistent run time over many years. The GI 275 only runs for 1 hour, which is the reason I didnt go for that either.

Replacement G5 batteries are under $200 dollars, so worst case you replace them every 3 years.

You should be vigilant about replacing the main battery regardless, they arent that expensive all things considered when the alternative is being stuck on the ground in the middle of no where. This is also why more people should start looking into lithium based batteries, they can handle deep drains much better and will be able to be charged without damage after being drained deeply.

[David Lloyd]

7 hours ago, jlunseth said:

The one thing to watch out for in that failure mode, is that you need to stop using the AI as soon as the failure is annunciated. The gyro continues to spin for some time and you think you can get away with using the AI for awhile, but it starts to slowly slide off in one direction before it tumbles completely. If you continue using it you will get yourself in a graveyard spiral, or a climb or descent when you think you are level.

Vacuum indicator should be part of your instrument scan.  If (edit, not if, but when) the pump fails, cover your vacuum powered instruments before they start spinning down.  If you fly instruments very often, it is just about impossible not to look at an uncovered and failing instrument and will set up a spacial disorientation event.  Last pump failure I had was on an ILS approach in Little Rock. I saw the gauge twitch, go to zero and I said something ugly.  Wife saw the gauge and without either of us saying more, she tore off the cover of an NOS approach book and handed it to me to cover the AI.

[Tim Jodice]

2 hours ago, dzeleski said:

You cant fit a second alternator in a J as far as I am aware.

When you throw away your vacuum pump put this in it's place. 

https://www.aircraftspruce.com/catalog/eppages/sd20_alternator.php?clickkey=4300

[dzeleski]

1 hour ago, Tim Jodice said:

When you throw away your vacuum pump put this in it's place. 

https://www.aircraftspruce.com/catalog/eppages/sd20_alternator.php?clickkey=4300

Good to know thank you!

[Bolter]

What is viability of using a portable 12V battery source through the cigarette lighter to power a minimum of instruments in case of electrical failure?  I am thinking of these portable jump start packs.  As long as you keep current below the cigarette lighter's limit through judicious use of off-switches and circuit breakers, I would think you could keep a G5 and a turn coordinator going for quite some time, before consuming the G5's backup.

[Guest]

5 hours ago, dzeleski said:

 

You cant fit a second alternator in a J as far as I am aware. This is part of the reason I went with Garmin instead of Aspen. 2 hours wasnt enough for me personally. My G5s genuinely last about 4 hours, ive tested it. I would not expect the time to degrade much over 5 years because 100% charge displayed is not actually 100% charged, its most likely around 80%. This allows the battery to keep a consistent run time over many years. The GI 275 only runs for 1 hour, which is the reason I didnt go for that either.

Replacement G5 batteries are under $200 dollars, so worst case you replace them every 3 years.

You should be vigilant about replacing the main battery regardless, they arent that expensive all things considered when the alternative is being stuck on the ground in the middle of no where. This is also why more people should start looking into lithium based batteries, they can handle deep drains much better and will be able to be charged without damage after being drained deeply.

STC’d back up alternator for your Mooney.  I take care of 2 J models equipped with this system.

http://www.basicaircraft.com

Clarence

[toto]

2 hours ago, Tim Jodice said:

When you throw away your vacuum pump put this in it's place. 

https://www.aircraftspruce.com/catalog/eppages/sd20_alternator.php?clickkey=4300

The B&C is not STC’d for the J model though, right? This would require a field approval?
 

[jlunseth]

6 hours ago, dzeleski said:

 

You cant fit a second alternator in a J as far as I am aware. This is part of the reason I went with Garmin instead of Aspen. 2 hours wasnt enough for me personally. My G5s genuinely last about 4 hours, ive tested it. I would not expect the time to degrade much over 5 years because 100% charge displayed is not actually 100% charged, its most likely around 80%. This allows the battery to keep a consistent run time over many years. The GI 275 only runs for 1 hour, which is the reason I didnt go for that either.

Replacement G5 batteries are under $200 dollars, so worst case you replace them every 3 years.

You should be vigilant about replacing the main battery regardless, they arent that expensive all things considered when the alternative is being stuck on the ground in the middle of no where. This is also why more people should start looking into lithium based batteries, they can handle deep drains much better and will be able to be charged without damage after being drained deeply.

Stay tuned. I don't know about the J for sure, but I have discovered that one can be added to a 231 by putting it on the pad where the vacuum pump was. Of course, then you have no choice about whether to remove the vacuum. Requires FAA approval, if it works out I will let you know, and I don't know if it would apply to a J, that is a Lyc, 231 is a Conti, but the alternator system exists.

[Tx_Aggie]

10 hours ago, skykrawler said:

My 1982 J has a vacuum failure light on the annunciator panel. There is also a gauge.  My recent pump failure (also on a +30 year old pump!) was detected before the gyro spun down and the KAP-150 AP disconnected.  The failure was not the vanes in the pump, it was the frangible plastic coupler in the drive.  Had a recent oil seal replacement on the acc drive shaft.

I previously removed the Precise Flight standby (manifold) to eliminate the AD hassle and installed a G5 for a proper secondary.   It important to know the systems on your particular airplane - how else can you understand the consequences of failures?

 

I forgot to mention the annunciator was the first to indicate the issue. Had the vac pump pulled today and the failure was the same as you described. Mine ran for 1000 flight hours and 17 years. Pretty good run time I figure!

[Tx_Aggie]

8 hours ago, kortopates said:

The real problem you seem to be getting is that your Aspen was likely installed without using the Aspen EA100 AP adapter that would allow controlling your AP from the Aspen. Purely a significant  cost saving measure that eliminated the need to buy/install and wire up your AP so that original costly to maintain Century AI could be retired - instead it was just likely moved out of the way. But your "Backup AI" is actually your Primary AI since its the Century AI that drives your AP. The Aspen is really the backup. There are other options to get rid of the vacuum dependency but you probably should decide first if you like the Aspen system and want to integrate your AP in with your Aspen or go another route entirely.  if you stick with the Aspen, my personal choice would be to first update your Aspen Pro to the Aspen Pro Max to eliminate the vulnerability of bringing down the entire Aspen due to an iced pitot tube with failed pitot heat at cost of 5.5K then also add the EA100 adapter for about 3K and lastly add a real backup AI like a Garmin G5. Or you could just replace your vacuum pump and move on with a new appreciation of the your system installation vulnerabilities.  

Well articulated. My system appears to be exactly as you described. I’ve decided to take the latter position and just replace the pump with a better understanding of how things are wired for now. I’ve only had the plane now for four months and thought I had a pretty good idea of how things were connected! I do enjoy continuing to learn, thanks for the help!!

[Gatlin Gun]

22 hours ago, Tx_Aggie said:

I’m interested in considering chunking my vacuum system altogether but have been told the vac pump repair will only be about $500 to repair, which is also enticing. Does anyone know if a G5 is compatible as a backup AI for the Century 4 AP?

Tx_Aggie,

To answer your question directly: No, I'm pretty sure it won't. Not sure specifically for the Centruy 4, but I have the Century 41 autopilot, and the G5s do NOT work for the AP.  

I had 2x G5s installed last year with that exact hope that you're after: rip out the entire vacuum system, and be on my way with a G5 ADI sending inputs to the autopilot.  Century unfortunately won't take the G5 source.  Thus, I still have to have my vacuum system and old-school ADI for no other reason than source input to my Century 41 AP.  My future will be a Century replacement eventually...but waiting for the budget to catch up to my "needs".  

[Skates97]

8 hours ago, David Lloyd said:

Vacuum indicator should be part of your instrument scan.  If (edit, not if, but when) the pump fails, cover your vacuum powered instruments before they start spinning down.  If you fly instruments very often, it is just about impossible not to look at an uncovered and failing instrument and will set up a spacial disorientation event.  Last pump failure I had was on an ILS approach in Little Rock. I saw the gauge twitch, go to zero and I said something ugly.  Wife saw the gauge and without either of us saying more, she tore off the cover of an NOS approach book and handed it to me to cover the AI.

Note pad came in handy when my pump died. 

[skykrawler]

Any thoughts about continuing IFR flight with IMC for over two hours after an electrical failure doesn't seem wise.   Now.....I realize there is always special circumstances, but for most flights there is a close enough airport.

Even if your EADI continued to run, the main battery will run down and now no radio, transponder or ADS-B.

[larrynimmo]

There are tons of certified backups that are super reliable...each with its own battery...and then you also have some non certified equipment such as stratus AI with an iPad....frankly I think that relying on vacuum gages alone offer a much higher risk to safety.

I keep inoperable stickers available to cover any of my glass that fails so I don’t dwell on a failed instrument..I got rid of my vacuum using the aspen Promax and the E5 (as replacement for turn coordinator)

[Tx_Aggie]

9 hours ago, Gatlin Gun said:

Tx_Aggie,

To answer your question directly: No, I'm pretty sure it won't. Not sure specifically for the Centruy 4, but I have the Century 41 autopilot, and the G5s do NOT work for the AP.  

I had 2x G5s installed last year with that exact hope that you're after: rip out the entire vacuum system, and be on my way with a G5 ADI sending inputs to the autopilot.  Century unfortunately won't take the G5 source.  Thus, I still have to have my vacuum system and old-school ADI for no other reason than source input to my Century 41 AP.  My future will be a Century replacement eventually...but waiting for the budget to catch up to my "needs".  

Thanks for the response, typo in my part,  century 41 autopilot as well. We’re on the same page with the budget needing to catch up!! Are you in a J also?

[PeteMc]

Sounds like you need the Aspen EA-100 to get your autopilot to take cues from your PFD.  (Or confirm that you don't already have one and they didn't wire it correctly...)

Another option would be to look at the Garmin GI-275.  It works with a number of autopilots, but I'd still think you'd want to drive the autopilot from your Aspen vs. reaching to the non primary display to make heading changes, etc.

But the GI-275 will let you get rid of your vacuum system if you get the correct version.  With it you'll have another screen to dedicate to traffic or other duties to have less clutter on your Aspen.