Vacuum pump fails at 20 hours

[PMcClure]

I replaced my perfectly fine vacuum pump last annual with over 800 hours as part of preventative maintenance. Only to have it fail for no good reason a few months later.  $638 part that should cost about $100. Plus the cost to remove, replace, remove and replace. I have had similar experiences with batteries, alternators, starters, fuel pumps etc... It chaps my hide that these parts cost 5-10 times what they should but then fail and could kill you. And in general, recovering warranty value is a major hassle. Pump was a SIGMATEK AIR PUMP 1U128-006. 

 

Rant over. Thank you. 

[Cruiser]

Infant mortality is primary failure

your story goes a long way in validating "if it ain't broke don't fix it"

[RLCarter]

Go with a rebuilt Rapco, same warranty 2yr/1000hr at about a 1/3 the cost ($237.95)...just my $0.02

[PMcClure]

Thanks for the advice. I am generally in the "ain't broke don't fix it" camp. But general advise is to replace vacuum pumps at 500 if you fly IFR and depend on it. How many people subscribe to this theory. Or better to just let it fail whenever. 

 

[cnoe]

FWIW I'm using a Tempest vac pump with the vane wear indicator port that at least gives you some indication of health. I have no intention of randomly replacing it; I'm much more concerned with infant mortality. Instead I PLAN on its failure by utilizing an electric backup pump PLUS an electric standby attitude indicator. Then there's always Foreflight displaying the AHRS info from my Stratus. When (not if) my legacy vac pump craps out I have a few options to choose from.

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[Marcopolo]

PM,

 

  20 hours is extreme infant mortality.  Some pumps require a specific direction of rotation although I believe most Sigma-Teks are bi-directional.  Sorry to hear about this failure, glad you were in a position to notice it and return safely from it.

 

Ron

[jetdriven]

Was any Teflon tape or sealer used on the pipe  threads for install? Any silicone spray used to slip the highs on fittings? Were all the lines blown out or checked for deterioration? Do you have a CV1J4 filter? Anything other than air gets in that pump and it can fail very quickly 

Edited September 16, 2016 by jetdriven

[PMcClure]

21 minutes ago, cnoe said:

FWIW I'm using a Tempest vac pump with the vane wear indicator port that at least gives you some indication of health. I have no intention of randomly replacing it; I'm much more concerned with infant mortality. Instead I PLAN on its failure by utilizing an electric backup pump PLUS an electric standby attitude indicator. Then there's always Foreflight displaying the AHRS info from my Stratus. When (not if) my legacy vac pump craps out I have a few options to choose from.

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I'll check these points, thank you. I do know a new filter was installed and lines cleaned or replaced at annual. New filter ordered is a RAPCO RAB3-5-1.  Interesting point on the Tempest, I'll look into that. 

Regarding failure modes I have experienced 3 pump failures, one in IMC, 2 in VFR. 1st one failed at 500 hours, 2nd one was infant mortality as was this 3rd one. Mind you I only have about 800 hours flying.

My Ovation has a stand by pump and back up AI. The 1st failure was in an older Mooney with no back up pump or AI. That one was in VFR as was this last one, thank goodness. The failure in IMC was in my Bonanza which also had a history of erratic AP issues. It did not have a standby AI but did have a standby vacuum pump. I had fewer hours experience then. It took me a while to recognize diagnose and act. I don't want to do that in IMC again, but do practice partial panels more often as a result. 

Bottom line, it seems infant mortality is a bigger risk than flying around with an 800 hour pump. 

[peevee]

27 minutes ago, PMcClure said:

 

Bottom line, it seems infant mortality is a bigger risk than flying around with an 800 hour pump. 

Tough to say. Ours is at 600ish and at least based on anecdotal evidence I agree. Our A&P also seems to agree. 

Makes a good case for a Garmin or dynon digital doesn't it? 

[Mooneymite]

• I've always been a "wait until it fails" guy since the MTBF is so variable.  However, like CNOE, I've installed a Tempest with the vane wear indicator.  I suspect that when those vanes approach the limit, I'll replace the pump preemptively.  I've been incredibly lucky.  All four failures have been in clear weather, or on the ground....so, my time is coming.

[PMcClure]

9 minutes ago, Mooneymite said:

• I've always been a "wait until it fails" guy since the MTBF is so variable. 

That is kind of the point of the original rant. For $600 you think a pump would be more reliable or at least predicable. 

[jetdriven]

1 hour ago, Mooneymite said:

• I've always been a "wait until it fails" guy since the MTBF is so variable.  However, like CNOE, I've installed a Tempest with the vane wear indicator.  I suspect that when those vanes approach the limit, I'll replace the pump preemptively.  I've been incredibly lucky.  All four failures have been in clear weather, or on the ground....so, my time is coming.

Im a wait until it fails kinda guy, too,  but a vacuum system failure in IMC is quite a hazardous situation, so I mitigated it with the vacuum warning light and a standby electric attitude.  

[peevee]

Just now, jetdriven said:

Im a wait until it fails kinda guy, too,  but a vacuum system failure in IMC is quite a hazardous situation, so I mitigated it with the vacuum warning light and a standby electric attitude.  

you would think they could have a system that fires up the electric standby pump automatically when a low vac situation exists.

[cnoe]

1 hour ago, Mooneymite said:

• I've always been a "wait until it fails" guy since the MTBF is so variable.  However, like CNOE, I've installed a Tempest with the vane wear indicator.  I suspect that when those vanes approach the limit, I'll replace the pump preemptively.  I've been incredibly lucky.  All four failures have been in clear weather, or on the ground....so, my time is coming.

Im a wait until it fails kinda guy, too,  but a vacuum system failure in IMC is quite a hazardous situation, so I mitigated it with the vacuum warning light and a standby electric attitude.  

I wish mine was tied into the JPI's warning light which jumps out at me much more than the stock annunciator. Instead I added a small vac gauge in the middle of my panel that at least gives me a shot at seeing the failure quickly.

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[Mooneymite]

36 minutes ago, jetdriven said:

...so I mitigated it with the vacuum warning light and a standby electric attitude.  

Yes, my C has a Hi and LO VAC light to help with recognition before the gyros tilt.  I practice partial panel and in a Mooney, it's not too tough.  Adding to the confusion of Vac loss is the fact that you also lose your PC.  What a great help that is!  

However, loss of vacuum in IMC requires immediately notifying ATC and, in my opinion, declaring an emergency.

[201er]

33 minutes ago, cnoe said:

I wish mine was tied into the JPI's warning light which jumps out at me much more than the stock annunciator. Instead I added a small vac gauge in the middle of my panel that at least gives me a shot at seeing the failure quickly.

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I like how well organized your pannel is with all the checklists, labels, and even speeds on the gear handle. Did you add those?

[Oldguy]

4 hours ago, cnoe said:

FWIW I'm using a Tempest vac pump with the vane wear indicator port that at least gives you some indication of health. I have no intention of randomly replacing it; I'm much more concerned with infant mortality. Instead I PLAN on its failure by utilizing an electric backup pump PLUS an electric standby attitude indicator. Then there's always Foreflight displaying the AHRS info from my Stratus. When (not if) my legacy vac pump craps out I have a few options to choose from.

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Paul, I had Rickey put a Tempest on mine in 2014 and have not had any problem. But just in case, I am pretty much an exact copy of what cnoe has in his and test my standby every third flight or so.

[N201MKTurbo]

Did you disassemble the failed pump to see if you could tell what caused it to fail?

[Mooneymite]

19 minutes ago, N201MKTurbo said:

Did you disassemble the failed pump to see if you could tell what caused it to fail?

In all of mine, the drive shaft was sheared, but I suspect that was a result of worn vanes, not the cause.  

Edited September 16, 2016 by Mooneymite

[cnoe]

52 minutes ago, Mooneymite said:

In all of mine, the drive shaft was sheared, but I suspect that was a result of worn vanes, not the cause.  

Yeah those frangible drive couplings will let go pretty quickly if something impedes the vanes. That sure beats risking damage to something in the accessory case.

About 18 months ago I moved some stuff around in the vac system and must have got a small contaminant in the stand-by pump side of the system. The moment I turned the switch on to test it the coupling immediately popped and the gauge was instantly at zero. "Maintenance Induced Failure", and my fault entirely. Damn! After that I have been super-careful anytime the vac system is opened up 'cause even an old hose can shed rubber internally just pushing the hoses onto their fittings.

1 hour ago, 201er said:

I like how well organized your pannel is with all the checklists, labels, and even speeds on the gear handle. Did you add those?

A few months ago I replaced all my interior placards with a set from Higher Graphics that they allowed me to customize as desired. I added the gear speeds along with several other tweaks. I also chose to place my rocker-switch (small) labels "under" the switches as opposed to on the switch-cover top. They also included new labels for the fuel pull-drain and selector which I sorely needed.

[PMcClure]

1 hour ago, N201MKTurbo said:

Did you disassemble the failed pump to see if you could tell what caused it to fail?

sheared 

[N201MKTurbo]

1 hour ago, PMcClure said:

sheared 

Of course it sheared! The coupling shearing is not the failure, it is just the mechanism to keep it from destroying your engine when it fails.

Did you disassemble the pump to see what made it lock up? Did it have Teflon tape residue in it? did it have oil in it? Any other foreign matter in there? Was there any unusual wear marks on the chamber? Were the vanes still in tact and the hub cracked?

Edited September 16, 2016 by N201MKTurbo

[Guest]

In my airplanes I put the small vacuum gauge and the warning light for the SVS beside the AH, making it instantly apparent when it fails.

Clarence

[cnoe]

I struggle with acronyms sometimes. "Synthetic Vision System"?

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[Guest]

40 minutes ago, cnoe said:

I struggle with acronyms sometimes. "Synthetic Vision System"?

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Standby Vacuum System it uses engine intake vacuum as an emergency source.

Clarence