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Mystery Penetration 1975 M20F

N7186V

By N7186V
in Vintage Mooneys (pre-J models)

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N7186V Contributor

N7186V

Posted
Posted

I've been looking through my maintenance manual and IPC, but haven't been able to locate the purpose of the penetration shown in the attachment.  I can find the "connector" on the aft side of the baffling, but I can't seem to find what, if anything, is supposed to be connected to it.  I've had an oil cooling problem and we've done everything we can except overhaul the oil cooler.  Before I do that, I'd like to verify that this shouldn't be plugged and will maybe fix the airflow.

Thanks!

Mooney Penetration.jpg

KSMooniac Grand Master

KSMooniac

Posted
Posted

I bet it used to have a duct connected that ran to the vacuum pump or fuel pump for extra cooling.  Have you looked through the logbooks to see if there is a mention of such a mod?

I'd just cover it.

Guitarmaster Veteran

Guitarmaster

Posted
Posted

It should have a scat tube attached that blows on your fuel pump to keep the fuel pump cool. At least mine does.

Sent from my XT1254 using Tapatalk

  • Like 3
N601RX Grand Master

N601RX

Posted
Posted

The fuel pump and mags should have a cooling tube. The large one in the picture is for the fuel pump. The pump should have a shroud around it that the hose connects to. 

  • Like 2
Yetti Grand Master

Yetti

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Posted

Mine is a SCAT tubing that blows air on the prop governor.   I would think the nice chilly fuel flowing though the pump would be enough to cool the pump.    Now the prop governor would seem to need cooling since it has hot oil flowing through it.

look for an adel clamp of the same diameter in a line with the hole and the prop governor  

  • Like 1
N7186V Contributor

N7186V

Posted
  • Author
Posted
Just now, Yetti said:

On mine the  Mags have a couple of hard tubes at an angle that cool them

My mags have a hard tube as well, the smaller hole under the one I'm asking about.  I guess my circle was too large and encompassed a couple penetrations.  I'll dig around, thanks all.  I'm scrubbing the IPC for these suggestions now.  If only there was an electronic searchable version out there.

Yetti Grand Master

Yetti

Posted
Posted

I think I see the adel clamp down angling to the top corner of the prop governor in the second pic.  I don't think this stuff is in the Manuals.  The don't have that type of documentation back there.   I looked at the power plant section and did not see it.

I still can not find the Stall vane adjustment or even the parts in the parts manual.

 

Marauder Grand Master

Marauder

Posted
Posted

I also have a tube that cools the vacuum pump. I need to take some pictures when I am doing oil changes. These questions come up a lot!

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  • Like 1
Shadrach Grand Master

Shadrach

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Posted

As was previously said it is the cooling feed for a SCAT tube that ducts to the mechanical fuel pump housing.  It would be a good idea to replace it.  This time of year it's not a huge deal, but in August...

Yetti Grand Master

Yetti

Posted
Posted

There is some technology that allows real time data and other maintenance annotation on photos.  I am trying to figure it out.  It would be cool to have pictorial maintenance guides.

N601RX Grand Master

N601RX

Posted
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The tube circled is the fuel pump.  If it hasn't been removed the fuel pump will have a shroud around it with a matching size inlet.  Its in the parts manual.

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Yetti Grand Master

Yetti

Posted
Posted

Parts manual is no help. Under the Power Plant group,  In the baffle section the circled part is called "connector"

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mike_elliott Grand Master

mike_elliott

Posted
Posted
1 hour ago, N7186V said:

I've been looking through my maintenance manual and IPC, but haven't been able to locate the purpose of the penetration shown in the attachment.  I can find the "connector" on the aft side of the baffling, but I can't seem to find what, if anything, is supposed to be connected to it.  I've had an oil cooling problem and we've done everything we can except overhaul the oil cooler.  Before I do that, I'd like to verify that this shouldn't be plugged and will maybe fix the airflow.

Thanks!

Mooney Penetration.jpg

I had a scat hose and a shroud going to the fuel pump from this opening on my 1970 F when I owned it.

  • Like 1
Bob_Belville Grand Master

Bob_Belville

Posted
Posted
1 hour ago, Guitarmaster said:

It should have a scat tube attached that blows on your fuel pump to keep the fuel pump cool. At least mine does.

Sent from my XT1254 using Tapatalk

+1 for my E

Yetti Grand Master

Yetti

Posted
Posted

Are there really any legal fuel pump shrouds?  It is not in the manual, so what do we need an STC version or a TSO?   Can I replace it with the LED version?    How hot does it get back there behind in the low pressure area?

 

  • Like 1
Yetti Grand Master

Yetti

Posted
Posted

I would have to guess that the shroud would be impossible to get on without removing the engine from the airplane.  It was almost impossible to get the pump on and tighten and safety wire without it.  Took way longer than a V8 chevy for 2 bolts and a couple of hoses.

N601RX Grand Master

N601RX

Posted
Posted

Yes, it's factory equipment. I asked Maxwell about it once and he said that he occasionally get planes in that has it removed and just the hose pointed at the pump. It mounts with the same 2 bolts that hold the pump on and isn't easy to mount with the engine on the plane.

If you have the oil filter relocation then the supply point moves up to the baffle just in front of the #2 cylinder. 

  • Like 1
Shadrach Grand Master

Shadrach

Posted
Posted
19 minutes ago, Yetti said:

Are there really any legal fuel pump shrouds?  It is not in the manual, so what do we need an STC version or a TSO?   Can I replace it with the LED version?    How hot does it get back there behind in the low pressure area?

 

The shroud is factory equipment and it serves 2 purposes:

1) it circulates fresh air around the pump which helps to keep the fuel in its intended state... a liquid.

2) it acts as a collector if a fuel pump seal fails confining the leak to the inside of the shroud which has an overflow that is piped (hosed?) to a devoted drain tube on the bottom of the cowl.  

I just replaced the AN elbow that comes of the shroud at annual and yes it is a PITA to get to. I did not have to tilt the engine forward into the service position, but it is really not that big of a deal if needed. 

  • Like 1
Yetti Grand Master

Yetti

Posted
Posted

I am trying to get my head around.  How hot is it back there anyways.   If it is hot enough to boil fuel would the fuel lines outside the shroud not also boil fuel.   I would think the fuel injection lines sitting on top of the engine would boil fuel better until they are hit with pressurized fuel.  The shroud/hose assembly is only going to work while in flight or maybe a little air with the prop spinning in ground ops.  How hot is it back there?

Leaks.  There is a tell tale drain on the pump.  The pump housing would have to split or the diaphragm blow out the side.  Seems like a really, really remote chance.

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