Gary0747

Metal fuel line tubing maintenance

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With all the high time building on our airplanes has anybody been doing maintence or replacement of the metal fuel line tubing?  I was just reading about some failures on the Bonanza list due to fatigue or corrosion. I do not recall any incidents on Mooneys.

I do have some concerns with the tubing  around the fuel pump under the  pilots feet partly because it has likely been fiddled with several time over the years.  I would like to see a drawing or photo on the proper installation and support for the pump and tubing but have never found one.  

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Metal fuel lines fail when subjected to vibration or the wrong person turning the wrench.   The mooney fuel lines are pretty well supported and not subject to vibration.   At some point the rubber fuel line at the wing root should be replaced.    I checked mine and decided the if ain't broke don't fix it rule applies

 

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Mine are corroded and will require replacement. Mooney will make them up for you, at a steep price.... I’m trying to find out what the original wall thickness was to order tubing..

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This fuel line is from a customer’s Cessna 340.  It sprung a leak after landing.  Apparently it’s not unusual.

Clarence

47A1BD04-9AAF-47B1-8C51-DDABCB4F6617.jpeg

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All metals if subject to vibration have a fatigue life. These parts are seldom examined or replaced and there are instances of improper installation and inadequate support.   I think some of our airplanes originally had Dukes boost pumps that have now been replaced by Weldon.  Does anybody know if these are identical pumps with no changes in tubing or support needed?

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Tubing has a few ways of being manufactured...

And varying materials of construction...

Expect a Mooney fuel line to be different than the others... for better or worse..?

Installation details, leading to life in service...

 

Looks like Clarence’s C customer split at a weld line...?

That is a pretty big leak...

If that were to happen in flight, your Fuel Level and fuel totalizer would have a mismatch that would be hard to believe...

expect strong aroma of fuel if this happens in a Mooney.  Fuel lines are in and around or under the cabin only... not out in the wings...

Best regards,

-a-

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I have a eaton cnc tube bender

I can copy per sample sizes 1/4 to 3/4

When there various angles and rotation we build a tool jig for proper q.c.

 

I have a perfect 252 upper breather to duplicate in alloy, as I know that owners dont clean out the breather tubes and will corroide

I suggest 300 hours or five years>

 

Two ways to service, drop of at a radiator shop or plug one side and fill with tolulene.

 

Reinstall with firesleeve, heatshrink the ends to secure and keep from wicking.

I suggest high temp silicone adel clamps also

 

Service the assy, cost less than replacement, I see engine breather tubes worn thru as clamps are bad.

 

GB

 

 

lower 520 tube.jpg

GB 35 LOWER CAN TO RESV.png

ms21919wcj.jpg

IO470N.JPG

E225.JPG

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All metals if subject to vibration have a fatigue life. These parts are seldom examined or replaced and there are instances of improper installation and inadequate support.   I think some of our airplanes originally had Dukes boost pumps that have now been replaced by Weldon.  Does anybody know if these are identical pumps with no changes in tubing or support needed?
I just did the swap from the Duke's to the Weldon pump. They make a bolt in kit no mods needed. Only thing noticable is the pump is louder.

Sent from my E6810 using Tapatalk

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On 11/9/2018 at 3:59 AM, carusoam said:

Tubing has a few ways of being manufactured...

And varying materials of construction...

Expect a Mooney fuel line to be different than the others... for better or worse..?

Installation details, leading to life in service...

 

Looks like Clarence’s C customer split at a weld line...?

That is a pretty big leak...

If that were to happen in flight, your Fuel Level and fuel totalizer would have a mismatch that would be hard to believe...

expect strong aroma of fuel if this happens in a Mooney.  Fuel lines are in and around or under the cabin only... not out in the wings...

Best regards,

-a-

Anthony,

While it looks like a weld line, it’s actually the shadow caused by the fuel stream.  According to a fairly large twin Cessna maintenance shop this is quite familiar.  The lines corrode from the inside.

Clarence

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I had replaced the one that runs from the fuel pump to the firewall. It had cracked longitudinally at the compression fitting and was leaking fuel. My mechanic at the time got the part number and ordered another. Came over, put it on, handed me a bill for $150, parts and labor. This was before I enacted the Raptor Methodology© and kept track of my parts, expenses, and assisted with maintenance. Its wasn't terribly expensive for as important as it was. 

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Eesh...

Corrosion from the inside gives two challenges...

  • Leaking to the outside
  • bits of oxidized metal moving along the inside, towards the fuel distribution system...

There must be a filter or screen for that...

Best regards,

-a-

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2 hours ago, carusoam said:

Eesh...

Corrosion from the inside gives two challenges...

  • Leaking to the outside
  • bits of oxidized metal moving along the inside, towards the fuel distribution system...

There must be a filter or screen for that...

Best regards,

-a-

In the case of this 340, it was the main line from the tip tank to the fuel selector valve/ strainer filter assembly.  

Clarence

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Speaking of fuel lines-

How many of you have ever looked at the fuel line from the firewall to your fuel pressure gauge?  I have seen many that have never been replaced and when they came out they snapped like a glass tube. 

 

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