Vacuum pump failed

[TonyK]

On my way home from Nantucket last weekend the AI tipped over about half way home.  I went out this morning to pull the pump and knew it as soon as I looked at it.  Coupler bits were a dead give away.  I don't think this is going to buff out.

[GaryP1007]

On my way home from Nantucket last weekend the AI tipped over about half way home.  I went out this morning to pull the pump and knew it as soon as I looked at it.  Coupler bits were a dead give away.  I don't think this is going to buff out.

Curios as to how old the pump was?


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[LANCECASPER]

44 minutes ago, TonyK said:

On my way home from Nantucket last weekend the AI tipped over about half way home.  I went out this morning to pull the pump and knew it as soon as I looked at it.  Coupler bits were a dead give away.  I don't think this is going to buff out.

There once was a man returning from Nantucket . . .

[Hank]

1 minute ago, LANCECASPER said:

There once was a man returning from Nantucket . . .

Who flew along, his vacuum pump in a bucket . . 

[LANCECASPER]

Just now, Hank said:

Who flew along, his vacuum pump in a bucket . . 

The coupler sheared

Just as he feared 

[Mooneymite]

Good job, Mooney poets!  

I'm betting the failure occurred about 400 hours?

As I understand it, it is not the coupler that fails, it is the vanes break inside, the coupler does it's job of breaking to protect things "up-stream".

[TonyK]

And his attitude turned quickly to #$%^ it!

[TonyK]

I went through the logs and I can't find any entries for replacement but it could have been done in 2008 during overhaul so maybe 900hrs or perhaps never.  

Vane pieces and dust out both the intake and exhaust but I did get it to eventually roll through with some shaking and torque on the shaft.

[N201MKTurbo]

If you take it apart you will most likely find one of the vanes cocked in its slot and the hub cracked in half. 

You have nothing to lose at this point so take it apart and show us a picture of the guts.

[Hank]

14 minutes ago, N201MKTurbo said:

If you take it apart you will most likely find one of the vanes cocked in its slot and the hub cracked in half. 

You have nothing to lose at this point so take it apart and show us a picture of the guts.

I'd like to see what it looks like i side. When mine crapped out on a breakfast run, I wasn't able to get involved in the replacement. 

[TonyK]

For the curious.  I set the vanes at the retracted and extended limits.  I don't know what the limits are supposed to be but it doesn't look like there was much more holding them in on the elliptical portion of the rotation.  I will have to get my micrometer out but the vanes do look uneven.  Also notice the uneven carbon line around the shaft.  Either way it was toast.

 

[MIm20c]

26 minutes ago, N201MKTurbo said:

If you take it apart you will most likely find one of the vanes cocked in its slot and the hub cracked in half. 

You have nothing to lose at this point so take it apart and show us a picture of the guts.

I lost my pump a couple months ago, also around the 900 hr point.  One reason not to take it apart is if you need a core to trade in. I went the reman route and had no problem getting my $100 back even with a broken coupler identical to the picture above. 

[N201MKTurbo]

1 minute ago, MIm20c said:

I lost my pump a couple months ago, also around the 900 hr point.  One reason not to take it apart is if you need a core to trade in. I went the reman route and had no problem getting my $100 back even with a broken coupler identical to the picture above. 

That one actually looks rebuildadle. I bought a rebuild kit 20 years ago. I haven't had one that failed that wasn't compliantly trashed inside.  Usually they are scored and galled. 

[TonyK]

It must have blown out the coupler instantly.  I was expecting it to be completely shelled out inside as well.

[MIm20c]

Just now, N201MKTurbo said:

That one actually looks rebuildadle. I bought a rebuild kit 20 years ago. I haven't had one that failed that wasn't compliantly trashed inside.  Usually they are scored and galled. 

I talked to rapco at Oshkosh and asked how many core get rejected as unusable. Basically was told that if the unit (212cc for me) was recent (overhaul or new within the last 15? ish years) it is still viable as a core because most of the parts are replaced.  However, this was a factory overhaul not a parts kit overhaul. 

[Mooneymite]

Perhaps the trick is to replace the guts prior to failure?  Other than vane wear, there should be virtually no damage.

[RLCarter]

Had a vacuum pump failure on a new pump, pump rotated freely with no evidence of vane damage, replaced the coupler and all is good 400hrs total, 300hrs since new coupler. This was on a C-172 and the pump was new but had been purchased a few years earlier, the coupler would just crumble when you touched it. I think age and heat takes them out.

[N201MKTurbo]

6 minutes ago, Mooneymite said:

Perhaps the trick is to replace the guts prior to failure?  Other than vane wear, there should be virtually no damage.

Oh sure, next you are going to want me to remember anaversaries and birthdays...

[MIm20c]

3 minutes ago, N201MKTurbo said:

Oh sure, next you are going to want me to remember anaversaries and birthdays...

With a plane now these two dates are probably more important than AD compliance dates for the wellbeing of both the plane and myself. 

[takair]

My last two pumps failed at just over 500 hours.  In both cases the coupler sheared, but the veins were still intact.  I do wonder if the coupler gets brittle?  I still have one, will measure the veins on the last one out of curiosity. It is a rAPCO pump with a vein measuring window.  In general, it seems like pumps with more than 500 hours are on borrowed time.

[RLCarter]

24 minutes ago, takair said:

My last two pumps failed at just over 500 hours.  In both cases the coupler sheared, but the veins were still intact.  I do wonder if the coupler gets brittle?  I still have one, will measure the veins on the last one out of curiosity. It is a rAPCO pump with a vein measuring window.  In general, it seems like pumps with more than 500 hours are on borrowed time.

Someone had a Vac. pumps special going so we purchased one knowing ours had to be getting close..... But it just kept chugging along 

[PTK]

1 hour ago, takair said:

My last two pumps failed at just over 500 hours.  In both cases the coupler sheared, but the veins were still intact.  I do wonder if the coupler gets brittle?  I still have one, will measure the veins on the last one out of curiosity. It is a rAPCO pump with a vein measuring window.  In general, it seems like pumps with more than 500 hours are on borrowed time.

I'm of the opinion that the vacuum pump can go when it feels like it. It could be brand new and go in 10 hours or it could go without a hitch for 500 or more hours. I think pumps are dependable. Failures are more often than not due to liquid contamination from washing down the engine or even oil contamination. Also mishandling while installing and improper installation.

I carry a spare pump in the airplane just in case mine fails and I'm away somewhere.

[Andy95W]

I strongly recommend the Tempest vacuum pump.  Quality is excellent and the engineering that went into the oil diverter ring is well thought out.

 

 

[StevenL757]

18 hours ago, TonyK said:

And his attitude turned quickly to #$%^ it!

Tony, pleasure meeting you in Maine at the air show.  Glad this didn't turn into something worse.  Please let me know if you need anything, rides anywhere for any reason, etc.

Steve

[Tommy]

Get a new one. I am not sure if this applies to your engine but on my J, because it's a wet pump, it calls for a special seal plate. If you use the generic one then the oil will leak either explosively (which is good so that you know there is a problem but you end up with a oil soaked engine compartment) or insidiously (which is bad because you will take off with it).

Change your vacuum system filters as well to rid of contamination.