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Vacuum failure


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Flying today and HI started spinning, attitude indicator rotated, vacuum reads zero. Landed uneventfully, but now for the repair:

 

Is the vacuum pump the most likely item that failed? Could anything else cause this or should I go ahead and order the vacuum pump to expedite the repair?

 

Recommendations on which pump to use? I'm going to take the cowl off and look at what's currently installed, but wondering what kind of options I'll have.

 

No, not ready to go sans pump right now, but recognize that's the best way to go.

 

 

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It would be good to check your vacuum hoses first.  After some panel work, I found my vacuum was zero.  The shop checked, and the hose had come off at the firewall fitting.  It did not have a hose clamp and must have been knocked off during the panel work.  They reconnected it with a hose clamp and all was well...

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Don’t look in the logs yet....

How many hours did it have on it?

OK, you can look now... :)

Some die from infant mortality, for several reasons...

Others get past 500 hours before wearing blades... worn blades stick and snap off... ending the vacuum portion of the pump...

Some people OH them... realistically they are in the replace early and often category... others replace them with wet pumps that last extremely long...

Many toss them at 500hrs to keep things from going awry in IMC...

I’m guessing, you don’t fly in IMC?

Best regards,

-a-

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Sometimes strange things happen. My friend with an “F” model had a vacuum failure on start up recently. Scrutiny revealed a looseness in the elbow fitting in the top of the pump. The pump had been operating normally for hundreds of hours, but suddenly this became an issue. Engine mount interfered with tightening without first removing the pump, but that corrected the problem. 

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Also, be concerned for your vacuum instruments after a vacuum pump failure. When the vacuum suddenly fails karma the carbon dust from the vacuum pump blades camp suddenly flow back into the instruments. Good practice is to place a filter in between the vacuum pump and the vacuum instruments. There used to be a company called it clear view filter that made filters that were clear so you could see how much damage had been prevented by having the filter inline. The clear filters are no longer available but I'd still consider an installation of  A filter.  My vacuum pump recently failed at my mechanic said "that filter sure saved you a lot of grief " .

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I would be money that your vacuum (circled) has failed.  Your local A&P will have extensive knowledge in finding/replacing and appears to be easy to get to.

Past the pump, inside the cabin (generally), there is a suction regulator that can dial the exact pressure.  The fact that your vacuum gauge is zero, I would bet money this is the source of your problem.

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As is MooneySpace tradition, posting wide-angle shots of a target-rich environment invites (what is hoped to) be "constructive commentary."

Is your A&P/IA mad at you for some reason?  There's a lot of  "stuff" going on in there.  (Sorry, not constructive.) 

Find a screw and nut to plug up that open hole in the firewall.  Just inboard (above, in the picture) of the terminal block. 

Good luck!

tom

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Use some additional words to describe things...

Loose exhaust piping after annual.... pretty much describes the thing that delivers flaming hot exhaust to the muffler...

Is that what you mean?

That would be really bad! As in do not fly until fixed...

Or did you mean the big heater hose?  This coming loose probably not a big deal...?

Circled in the pic below? :)

Unfortunately, I don’t see an exhaust piping in the pic...

PP thoughts only, not a mechanic...

Best regards,

-a-

A10480A3-64B5-4973-8395-2078E85A0DBD.jpeg

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5 minutes ago, carusoam said:

Use some additional words to describe things...

Loose exhaust piping after annual.... pretty much describes the thing that delivers flaming hot exhaust to the muffler...

Is that what you mean?

That was kind of my reaction when I read that :o

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11 minutes ago, carusoam said:

Use some additional words to describe things...

Loose exhaust piping after annual.... pretty much describes the thing that delivers flaming hot exhaust to the muffler...

Is that what you mean?

That would be really bad! As in do not fly until fixed...

Or did you mean the big heater hose?  This coming loose probably not a big deal...?

Circled in the pic below? :)

Unfortunately, I don’t see an exhaust piping in the pic...

PP thoughts only, not a mechanic...

Best regards,

-a-

A10480A3-64B5-4973-8395-2078E85A0DBD.jpeg

 

Yes, that is the piping that I was referring to. My '?' before "exhaust piping" was meant that I wasn't sure what this piping was for. Still developing my aviation vocabulary and knowledge-base. Either way, it seems like this could allow exhaust fumes/carbon monoxide into the cabin. Correct me if I'm wrong..

 

Photo was taken after I reattached it and secured the clamp. I'll have a mechanic inspect it when he's working on the vacuum before I take it in the air again.

Edited by BrettKS
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Have less fear....

1) But get to know where exhaust can enter that piece of hose... it comes from upstream...

2) If the exhaust is leaking out of an exhaust tube, and that hose was missing, and you had the slide gate open to get air/heat into the cabin... see the slide gate control wire?  The bigger problem is hot gasses being released under the cowl.... a large fire risk... 

3) A broken heat muff allows exhaust into the heat system... using the heat allows the errant exhaust into the cabin...

4) The heat muff surrounds the muffler... and hides the broken parts...

5) Got a CO monitor?  Now is the day to order one... :)

Best regards,

-a-

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8 hours ago, BrettKS said:

I'm glad I took the cowl off. Fresh out of annual and noticed that this ? exhaust piping was completely loose and easy to pull off. I imagine this could have been an issue in flight.

1566917007910557644199337295612.jpg

That’s called “Scat” ducting, it delivers hot air from the muffler shroud to the cabin via the shut off valve.  Your engine compartment wiring could use some attention and tidy up.

Clarence

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From now on I will be replacing the pump on a preventive maintenance basis.

About four weeks ago I headed over the top on a 250nm flight.  About 150 nm or so was over solid overcast with a METAR and forecast of VFR at my destination.  I got about halfway across above the overcast and saw the AI turning severely.  I looked at the horizon and I was wings level.  I looked at the suction gauge and it was on zero.

 It wasn’t serious because I was confident that I had VFR ahead and I had about five hours of fuel on board.  That said I still felt uneasy.  If I would have had to go through the overcast it would have been less than ideal without my vacuum driven instruments.

It got MY attention!, 

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1 hour ago, M20Doc said:

That’s called “Scat” ducting, it delivers hot air from the muffler shroud to the cabin via the shut off valve.  Your engine compartment wiring could use some attention and tidy up.

Clarence

Hey @M20Doc, what does "SCAT" actually stand for?  It seems a rather unfortunate name more reminiscent of proctology... :rolleyes:

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8 minutes ago, jaylw314 said:

Hey @M20Doc, what does "SCAT" actually stand for?  It seems a rather unfortunate name more reminiscent of proctology... :rolleyes:

I have to look it up, but it is a product of the Thermoid Co.  Scat, Sceet, Cat and Ceet are common ducting solutions.

Clarence

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