Vacuum Pump Failure - VFR

[Pictreed]

Ya it was VFR, didn't want to make this seem like click bait.  

I was doing an instrument proficiency review yesterday (I know, I can't believe I let a year slip without approaches too) and the vacuum pump failed.

I might have my mechanic replace it but I thought about doing it myself.  What should I watch for when doing this?

It's a '65 E with stock windshield and access - YAY!

Thanks, Tim

[RLCarter]

Order the wrench when you order the pump, makes life easier

[Guest]

With the pump off look carefully for signs of oil leakage from the drive shaft seal.  Nothing will kill you new pump faster than oil getting inside it.  
As with everything, use new lock washers, 4 MS35333-40 internal star washers.

Clarence

[Pictreed]

Just now, M20Doc said:

With the pump off look carefully for signs of oil leakage from the drive shaft seal.  Nothing will kill you new pump faster than oil getting inside it.  
As with everything, use new lock washers, 4 MS35333-40 internal star washers.

Clarence

I was hoping you'd reply :-)  Thanks.

[neilpilot]

Don’t forget to have your mechanic or another A&P sign off on the replacement. Also a new filter maybe a good idea.

[Pictreed]

Thanks Neil, I've already talked to him and an IA.

[Matt Ward]

20 hours ago, Pictreed said:

Ya it was VFR, didn't want to make this seem like click bait.  

I was doing an instrument proficiency review yesterday (I know, I can't believe I let a year slip without approaches too) and the vacuum pump failed.

I might have my mechanic replace it but I thought about doing it myself.  What should I watch for when doing this?

It's a '65 E with stock windshield and access - YAY!

Thanks, Tim

Do you mind talking a little about how it failed and what happened in flight?  Any warnings that you can look back on now?  I've got a DG that is processing a bit too much and an AI taking longer than I'd like to stand up and wondering if my pump is on the verge of failing.  I haven't seen any low vacuum lights (besides low rpm ground ops) but I'm trying to watch it closely.

[SantosDumont]

I had mine fail on me a few years ago, but it was on the ground.  It had probably failed in flight but I didn't notice.  Went to start the plane and the AI didn't spin up (AI is my only vacuum powered instrument) and the vacuum power indicator was at 0.  Changing it is super easy if you have that wrench.  They only have a life of 500 hours or so though so my plan next time it fails is to just change my AI with a AV-30 or Garmin 275.

[RobertGary1]

I’ve never had a warning when one was about to fail. I have a cockpit voice annunciator that tells me it failed. But it’s really just a third backup to my AHRS based systems. 
 

-Robert 

[Hank]

When mine failed, I noticed it during runup before flying home from breakfast. Made it all 33 nm home VFR, just didn't look at the wildly bobbing, crooked AI and didn't use the DG or Brittain to get back. The Low Vac light was on, and the Vac Gage was pointing at 0. With a new pump, everything was back to normal.

[RLCarter]

I’ve 2 fail and seen maybe 5 more, each time it was the shear coupler,   one guy had a spare coupler that was several years old and it crumbled into pieces getting it out of the bag. My second pump that failed got a new coupler installed and made into a electric drive test pump for my IA, 

Edited June 22, 2020 by RLCarter

[David Lloyd]

I've had about 10 pump failures, all in the Bo.  Only one produced low pressure for a while before failing.  Twice, the pressure indicator flicked up and down a couple times and went to 0 over the period of a couple seconds.  Not much warning.  Others died during startup or silently passed on during flight.

[0TreeLemur]

On 6/21/2020 at 2:33 PM, M20Doc said:

With the pump off look carefully for signs of oil leakage from the drive shaft seal.  Nothing will kill you new pump faster than oil getting inside it.  
As with everything, use new lock washers, 4 MS35333-40 internal star washers.

Clarence

Wish we had a FAQ section.  I'd nominate this for inclusion.

[bradp]

Wet pumps available ?

[Pictreed]

On 6/22/2020 at 9:34 AM, Matt Ward said:

Do you mind talking a little about how it failed and what happened in flight?  Any warnings that you can look back on now?  I've got a DG that is processing a bit too much and an AI taking longer than I'd like to stand up and wondering if my pump is on the verge of failing.  I haven't seen any low vacuum lights (besides low rpm ground ops) but I'm trying to watch it closely.

I'm super busy at work so I just had my mechanic replace it.  Looks like $681 and took a day.

My DG has been really weird and precession was noticeable.  I'm not sure if that's because the pump was going bad.  I think the vanes just separate and go from good to broke; however, don't take my word for it.  I'll let you know how it reacts now.  Personally I'd like to upgrade and get rid of the DG you have to reset all the time.

There were really no indications.  The instructor asked if I'd checked the suction and I said yes, it was bouncing around in the upper part of the green as it usually does.  My mechanic asked if it always bounced...yep.  Maybe it should have a restrictor???  I departed and turned out, slipped on my foggles and looked down to an AI that said I was in a steep climbing right hand bank.  I was actually in left shallow banking climb.  I assume it failed abruptly around 700' or so.

The only thing that really made me question it's  reliability is that the needle was all the way down at idle.  I'll let you know if that's changed.

 

 

[Pictreed]

On 6/22/2020 at 10:26 AM, SantosDumont said:

I had mine fail on me a few years ago, but it was on the ground.  It had probably failed in flight but I didn't notice.  Went to start the plane and the AI didn't spin up (AI is my only vacuum powered instrument) and the vacuum power indicator was at 0.  Changing it is super easy if you have that wrench.  They only have a life of 500 hours or so though so my plan next time it fails is to just change my AI with a AV-30 or Garmin 275.

I agree.  No instrument lights and no AI backup.  I think I'll migrate towards a G5 or something.  Fix multiple problems with one purchase.

[Pictreed]

On 6/22/2020 at 10:54 AM, RobertGary1 said:

I’ve never had a warning when one was about to fail. I have a cockpit voice annunciator that tells me it failed. But it’s really just a third backup to my AHRS based systems. 
 

-Robert 

Robert, how does it read the vacuum to send a signal.

My mechanic said the step is connected to the same vacuum, I guess if the vacuum gauge failed I could look outside for the step deployment.  LOL just kidding.

[RobertGary1]

28 minutes ago, Pictreed said:

Robert, how does it read the vacuum to send a signal.

My mechanic said the step is connected to the same vacuum, I guess if the vacuum gauge failed I could look outside for the step deployment.  LOL just kidding.

I used a switch off a piper that turns on a light when vacuum drops. I connected it to my voice annunciator. 
 

-Robert 

[67 m20F chump]

You could have put that money towards a couple of G5’s and ditched the pump.

[Mooneymite]

As a vacuum pump spins, the vanes are slowly worn down, when one (or more) of the vanes reach a critical point, it jams the pump, causing the coupler to break, disconnecting it from the accessory drive.  Often you hear people blame failure of the coupler for pump failure whereas it is actually a result of vane wear.

Because of this "decouple", vacuum failure usually is sudden and complete. The pump works fine until it doesn't.

At least one of the vacuum pump models feature a port for checking vane wear which sounds like a good idea, but dry vacuum pumps will all eventually fail due to vane errosion, some sooner than later.  

Seems like most of my vaccum pumps fail after 500 hours, or so.  That's a great reason to practice partial panel instrument skills.  Losing the AI and DG IMC need not be fatal.

[RobertGary1]

The problem is that there are some things that only a vacuum driven attitude indicator can do. Filmed this from the cfi perch. 
 

-Robert 

[RLCarter]

6 hours ago, RobertGary1 said:

The problem is that there are some things that only a vacuum driven attitude indicator can do. Filmed this from the cfi perch. 
 

-Robert 

DCE3C143-2107-4F39-AFB0-E76CB417A9F1.MOV

Nice.....Ive seen a DG that but never AI

[carusoam]

Looks like the back-up instrument needs a back-up... 

-a-

[47U]

Not that uncommon, apparently.  I was ground running to leak/ops check an FP-5 I had just installed.  It would do this on every 10th or so attempt to erect.  I’ve since replaced it.

 

[outermarker]

Isn't there a Low Vac and High Vac  warning lights in the artificial horizon? And isn't there a test button that you press to test the bulbs?