Vacuum system issues

[SLOWR426]

Hi all, we’ve been having intermittent DG issues / tumbling in our ‘67 F-model and last flight both the DG and attitude indicator tumbled / failed at the same time.  It’s strange because most of the time the vacuum gyros work fine.  2 weeks ago an oil leak was fixed at the vacuum pump.  What could cause intermittent vacuum issues?  And where is the vacuum regulator located? Does this intermittent issue sound more likely to be the pump, regulator or vacuum lines/connections?

I’ll have my mechanic look at it, but I’m curious as to your thoughts and any Mooney-specific nuances.  I’m hoping to train for my instrument rating this Summer in the plane.

Thanks in advance

[LANCECASPER]

The first thing I'd do after getting the vacuum system figured out is to put in a backup attitude indicator, preferably electric. Too many people think they are proficient at partial panel in IFR (turn coordinator) until it really happens under a stressful situation and we lose too many pilots every year to that.

[EricJ]

Do you have a vacuum/suction gauge?   What does it say?    It sounds like you may have developed a leak somewhere.   The regulator/manifold is usually on the cabin side of the firewall behind the instruments.

 

[carusoam]

+1 for vac gauge readings…

+1 for looking for leaking tube or disconnected tube…

you know if your DG fails going opposite direction your AI is pointing….. your vac system is failing…. IR101…

 

Hard to do any problem solving without the vac gauge reading…  what does yours say?

Vac pumps are pretty digital… work/don’t work, not much in between…

Vac regulators don’t hide very easily from any mechanic…

Any more challenging than that…

G5

GI275

G3

-a-

[cliffy]

Do you have a vac gage or just a low vac light (red)?  Is the light on or the gage at zero?

Now IF a second Ai is ever wanted one could always get a good used one and power it from a (do I dare say?) from a venturi mounted under the airplane and then that gyro would NEVER lose vacumn as long as the airplane was flying!  :-) :-) Simple, cheap, fail safe. What more could one ask for? 

Shields are up! 

[Guest]

On 6/20/2022 at 12:34 PM, SLOWR426 said:

Hi all, we’ve been having intermittent DG issues / tumbling in our ‘67 F-model and last flight both the DG and attitude indicator tumbled / failed at the same time.  It’s strange because most of the time the vacuum gyros work fine.  2 weeks ago an oil leak was fixed at the vacuum pump.  What could cause intermittent vacuum issues?  And where is the vacuum regulator located? Does this intermittent issue sound more likely to be the pump, regulator or vacuum lines/connections?

I’ll have my mechanic look at it, but I’m curious as to your thoughts and any Mooney-specific nuances.  I’m hoping to train for my instrument rating this Summer in the plane.

Thanks in advance

If the problem started after the oil leak was repaired, possibly the hoses at the pump were crossed, or the hose from the pump has collapsed internally.

From the IPC, a typical vacuum system.

Clarence

[SLOWR426]

Thanks all.  Turns out the pump just failed.  Apparently there’s an indicator on the vacuum pump body that spins when you pull the prop through, which is not indicating.  And there’s plastic debris there also.  Looks like I’ll be ordering a Rapco 211CC for my IO-360 A1A.  But thanks for the tips; this is an education for me.

[carusoam]

3 minutes ago, SLOWR426 said:

Thanks all.  Turns out the pump just failed.  Apparently there’s an indicator on the vacuum pump body that spins when you pull the prop through, which is not indicating.  And there’s plastic debris there also.  Looks like I’ll be ordering a Rapco 211CC for my IO-360 A1A.  But thanks for the tips; this is an education for me.

Did you find a vac gauge in the cockpit for that?

not as critical if VFR only…

Vac pumps don’t give much of a warning that they are about to fail…

They throw a carbon blade that wipes out the rest of them…

Potential Carbon bits and dust everywhere inside the vac system… depending on the plumbing… filter location compared to the pump…

 

PP thoughts only, not a mechanic…

Best regards,

-a-

[jetdriven]

If you really going to fly in the clouds you really want a back up electric attitude indicator and you want a vacuum gauge and preferably a low vacuum light as well. Because as you can tell, vacuum failures are insidious

[SLOWR426]

Anyone know how to remove the bottom Left nut from the vacuum pump?  Holly $hit it looks impossible to get a wrench and hands on there 

[47U]

14 minutes ago, SLOWR426 said:

Anyone know how to remove the bottom Left nut from the vacuum pump?  Holly $hit it looks impossible to get a wrench and hands on there 

https://skygeek.com/tools-equipment/vacuum-pump-wrenches/?msclkid=a6a3d815a1b5174c05f4baaa8735a229

[Mooney-Shiner]

2 hours ago, SLOWR426 said:

Anyone know how to remove the bottom Left nut from the vacuum pump?  Holly $hit it looks impossible to get a wrench and hands on there 

Second vote for Rapco Wrench. As far as replacement vacuum, I installed AA3215CC and had no problems. It considered the best one.

[EricJ]

+1 the Rapco wrench works fine.   

[cliffy]

If you don't have the rapco wrench many have been removed with a blade screwdriver and tapping with a hammer, 

Goes back on the same way It does ruin the finish of the nut but if you are trapped away from home (field repair :-) it works fine. 

It was done this way long before the rapco wrench, 

Kinda gorilla method but- 

Always use new lock washers and a new nut if you can get it.  

[Guest]

There’s really nothing wrong with vacuum pumps.  Replacing your vacuum pump at 500 hour intervals is cheaper than back up batteries for most new fancy electronic attitude indicators.

Clarence

[ArtVandelay]

There’s really nothing wrong with vacuum pumps.

I saved 20 lbs removing vacuum system (pump, hoses,electric backup pump, etc).

[cliffy]

I saved 42 pounds by dumping everything and going single screen 10" Dynon HDX  :-)

[Ragsf15e]

Have you seen the engine on @M20Doc comanche?! He don’t care about saving no 40lbs!  

[MBDiagMan]

Been there done that SLOW.  

A couple of years ago I was on a flight that was about 250 miles.  It was about 30 miles of clear sky and then a low, solid overcast below until about 30 miles from my destination where it cleared up.  I was on top, about halfway when I lost my vacuum pump.  I covered the vacuum instruments and went on.  Very thankfully it was indeed clear sky at my destination.  I am coming up on about 300 hours on my dry vane vacuum pump since it’s replacement and I’m considering replacing it at 400 hours as a preventive maintenance item.

[Marauder]

Been there done that SLOW.  
A couple of years ago I was on a flight that was about 250 miles.  It was about 30 miles of clear sky and then a low, solid overcast below until about 30 miles from my destination where it cleared up.  I was on top, about halfway when I lost my vacuum pump.  I covered the vacuum instruments and went on.  Very thankfully it was indeed clear sky at my destination.  I am coming up on about 300 hours on my dry vane vacuum pump since it’s replacement and I’m considering replacing it at 400 hours as a preventive maintenance item.

I was never happier than the day I ditched my vacuum pump. I used to do what you’re thinking of doing. I’d replace a pump after 500 hours. That changed when I had an infant mortality of a brand new pump. At one point I even considered going to a wet pump.


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[cliffy]

7 hours ago, Ragsf15e said:

Have you seen the engine on @M20Doc comanche?! He don’t care about saving no 40lbs!  

40 lbs isn't even taxi fuel in that gas guzzler!  :-)

The bad part is I remember when they came out new from Piper!

[cliffy]

5 hours ago, Marauder said:

I was never happier than the day I ditched my vacuum pump. I used to do what you’re thinking of doing. I’d replace a pump after 500 hours. That changed when I had an infant mortality of a brand new pump. At one point I even considered going to a wet pump.


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I have to agree now that I dumped all the old stuff for a Dynon panel

Never thought the transition would be so dramatic even to how much "consideration" on every flight was given to possible panel failures. 

Gyros, fuel gages, engine gages, etc The list goes on and on. "How long will it be until another instrument starts acting up"?

Here's a better question-  How many of you can say that EVERYTHING on your panel is working perfectly and as it was designed and delivered when new?

I'm a believer now. 

Its time to realize that the panel we look at is in some instances, maybe most, that panel is a half century old and we bank our lives on what it is displaying during IMC flight. How many of you are flying IMC with vac  gyros that haven't been out of the panel in 30+ years? How many of you can listen to the gyros winding down when you shut the engine off at the end of a flight? That stuff is getting old folks and  in the near future its gonna fail.

How many millions or revolutions have the gyros done since they were new? How long can the original bearings and lube last?

How many of you are driving 30+ year old cars to work every day?  WHY ARE YOU NOT DOING THAT? You fly a 30+ year old airplane don't you (and with just the minimum amount of repairs and maintenance you can get by with,( "how cheap can I get by with on this annual this year")?

If we want to keep flying these antique airplanes (AND YES they are antique) we have to really consider how we are going to bring them up to the 21st century in reliability. The basic airframe is not a problem. The panel is a different story. Especially if you are banking your life on it in  IMC flight!

Edited July 2, 2022 by cliffy
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[SLOWR426]

We replaced the vacuum pump successfully today.  Here’s the tool I fabricated which sort-of helped, and the screwdriver/hammer method.  Will use forcepts next time. Thanks for those tips.

[cliffy]

To start the nut on the stud one can take a bent piece of coat hanger 90 degrees with a 1/4"  leg to hold the nut on the end of the stud as you use the screwdriver to carefully turn it to start it on the threads.