Fuel line crack?

[dzeleski]

Hi all, wrapped up an oil change and gave the fuel lines an inspection. I seem to have a crack of some kind on one of the joints. The line does not appear to leak at this point so im thinking this is an outer layer? I have not run it up after finding it as I would rather not have a fire. Am I going to need a new line here or is this fixable?

Attached two photos, one good line and one with the crack.

Thanks!

[carusoam]

Great pics Dzel!
 

Looks like something has failed...

Fortunately, that is probably a Lycoming part that should be readily available...

You wouldn’t want to delay replacing it because air leaking in or fuel leaking out won’t be very good...

Seeing if @M20Doc is around... (fuel spider line with a broken weld(?) at the spider)

Best regards,

-a-

[dzeleski]

4 hours ago, carusoam said:

Great pics Dzel!
 

Looks like something has failed...

Fortunately, that is probably a Lycoming part that should be readily available...

You wouldn’t want to delay replacing it because air leaking in or fuel leaking out won’t be very good...

Seeing if @M20Doc is around... (fuel spider line with a broken weld(?) at the spider)

Best regards,

-a-

Definitely not moving it until someone can tell me its safe or not To my mostly untrained eyes it looks unairworthy so ill consider it is until further notice.

[larryb]

I had to replace on on my J once. It was about $100 and they come straight. You have to form the bends yourself. You can bend it around a socket or anything with a suitable radius.

[Guest]

It appears that the solder joint holding the end fitting to the stainless steel tube has cracked.

FAA AD2015-19-07 drives you to compliance with Lycoming SB342G which says to inspect for cracked fuel lines among other things.  As it does not differentiate between lines and solder joints, I’d say your line requires replacement.

From the picture I’d say it cylinder #1, part number 9, I’ve had the best luck with Lycoming lines versus aftermarket.

https://www.lycoming.com/sites/default/files/Fuel Line and Support Clamp Inspection and Installation.pdf

Clarence

Edited April 26, 2020 by M20Doc

[dzeleski]

4 hours ago, M20Doc said:

It appears that the solder joint holding the end fitting to the stainless steel tube has cracked.

FAA AD2015-19-07 drives you to compliance with Lycoming SB342G which says to inspect for cracked fuel lines among other things.  As it does not differentiate between lines and solder joints, I’d say your line requires replacement.

https://www.lycoming.com/sites/default/files/Fuel Line and Support Clamp Inspection and Installation.pdf

Clarence

Thats what I figured, thank you for the confirmation.

[dzeleski]

4 hours ago, larryb said:

I had to replace on on my J once. It was about $100 and they come straight. You have to form the bends yourself. You can bend it around a socket or anything with a suitable radius.

You are correct, $110 shipped and it will apparently be here Tuesday. Ill use the old line as a template.

@M20Doc TY for the part number, ordered.

[carusoam]

Also check the support for that line...

Things that cause cracks are often related to vibration and supports not holding the lines very well... or not Damping the vibration... (similar to wires)

The hose clamp looking supports in Docs drawing...

PP thoughts only, not mechanically inclined...

Best regards,

-a-

 

[dzeleski]

8 minutes ago, carusoam said:

Also check the support for that line...

Things that cause cracks are often related to vibration and supports not holding the lines very well... or not Damping the vibration... (similar to wires)

The hose clamp looking supports in Docs drawing...

PP thoughts only, not mechanically inclined...

Best regards,

-a-

 

Valid point and it’s actually something I checked the second I saw the crack. All the little rubber clamps are in good shape and seem to be holding the lines tightly. I’ll make sure when the new line is installed the clamp looks good. Thank you!

Edited April 26, 2020 by dzeleski

[MikeOH]

You might consider replacing the zip-tie on the pushrod tube with an Adel clamp.  Eventually vibration will cause it to cut through the metal tube.

[Yetti]

Airpower had Superior for like $50.

[Guest]

16 minutes ago, Yetti said:

Airpower had Superior for like $50.

I’ve had lean flow from some Superior lines, switched back to a Lycoming lines and the mixture returned to normal.

Clarence

[PT20J]

2 hours ago, M20Doc said:

I’ve had lean flow from some Superior lines, switched back to a Lycoming lines and the mixture returned to normal.

Clarence

Interesting, Clarence. I wouldn't expect the lines to have much affect on flow unless they were really undersized. Did you happen to measure the ID? I think the spec is .085-.090".

Skip

[MikeOH]

13 minutes ago, PT20J said:

Interesting, Clarence. I wouldn't expect the lines to have much affect on flow unless they were really undersized. Did you happen to measure the ID? I think the spec is .085-.090".

Skip

Well, that diametrical difference represents over 10% in area.  Just sayin'

[PT20J]

12 minutes ago, MikeOH said:

Well, that diametrical difference represents over 10% in area.  Just sayin'

That was my point. The flow should be relatively insensitive to the diameter. The specification is from Precision Airmotive for the RSA injection system. They don't supply the lines -- that's an engine manufacturer's part. Might be an issue if lines from different manufacturers were mixed on the same installation.

Skip

[Guest]

50 minutes ago, PT20J said:

Interesting, Clarence. I wouldn't expect the lines to have much affect on flow unless they were really undersized. Did you happen to measure the ID? I think the spec is .085-.090".

Skip

I didn’t measure the line.  It was on a Bravo, the owner complained of higher EGT on that cylinder after the line was installed.  I ordered a Lycoming line and installed it, the EGT return to normal.

The ID of the line should be greater than the nozzle ID, I think the line has some silver solder inside.

Clarence

[MikeOH]

41 minutes ago, PT20J said:

That was my point. The flow should be relatively insensitive to the diameter. The specification is from Precision Airmotive for the RSA injection system. They don't supply the lines -- that's an engine manufacturer's part. Might be an issue if lines from different manufacturers were mixed on the same installation.

Skip

And, the point I failed to communicate, is that 10% is a pretty significant difference to me!  IOW, an 0.005" diameter difference affects area by 10%.  No idea if a 10% area difference makes an appreciable difference in flow in a tube with a large length/diameter ratio, but I would not just assume it's insignificant.

If Lycoming supplies on the high side of tolerance, and brand "X" on the low side...

Edited April 28, 2020 by MikeOH
area not diameter

[PT20J]

3 minutes ago, M20Doc said:

I didn’t measure the line.  It was on a Bravo, the owner complained of higher EGT on that cylinder after the line was installed.  I ordered a Lycoming line and installed it, the EGT return to normal.

The ID of the line should be greater than the nozzle ID, I think the line has some silver solder inside.

Clarence

When I was in college, I had a summer job working at a TV station. One summer I worked in the tape room. We had an entire shelf full of Scotch tapes and one new, unused Memorex tape. No one ever used the Memorex and when I asked why, all I got was a shrug. So, next commercial spot we had to tape, I picked the Memorex. It clogged a head and we had to do the whole thing over and I got chewed out. Ever since, I've been leery of trying brand X.

[Eight8Victor]

2 minutes ago, PT20J said:

When I was in college, I had a summer job working at a TV station. One summer I worked in the tape room. We had an entire shelf full of Scotch tapes and one new, unused Memorex tape. No one ever used the Memorex and when I asked why, all I got was a shrug. So, next commercial spot we had to tape, I picked the Memorex. It clogged a head and we had to do the whole thing over and I got chewed out. Ever since, I've been leery of trying brand X.

Beta or 3/4”? 

[PT20J]

Just now, Eight8Victor said:

Beta or 3/4”? 

I'm older than that: 2" quadraplex

[carusoam]

Hmmm....

effects of pressure, flow, and diameter...

Oddly, doesn’t usually take into consideration the surface of the tube...

Mostly because the fluid running through doesn’t stick very well... if it did, the layers of fuel don’t stick to each other...  

If it were sticky and gooey or. Thick like molasses... the surface area and material would play a much larger role...

Length and diameter are the sources of drag in a fuel lines... bends would also add to the drag...

Changing the diameter... can do some odd things besides increasing the pressure drop...

Fluid flowing in the tube... like air over a wing... can change from laminar flow to turbulent flow... which may be the reason for not selecting brand X...   (for more information... look up the ‘Reynolds number’.  )

Flow in a tube is all about the cross sectional area... so if you cut the ID by 10% it will have a squared effect on the pressure change/ volume of flow...

PP thoughts only, not a rheologist... we always used Memorex, bought on Canal St, NYC for cash... they were looow cost...  I must have been early in the CB evolution...

Best regards,

-a-

[PT20J]

RSA fuel injection systems meter fuel by controlling the pressure drop across the metering jet which thus controls the flow rate. The nozzles atomize the fuel and provide a restriction on one side of the metering jet. The metering systems adjusts the pressure on the other side of the jet against this restriction to adjust the flow. The plumbing between the jet and the nozzles is sized so as to be out of the picture. The RSA specification states that an 1/8" OD stainless tube with any ID between .085 and .090" is acceptable. Clarence probably got a defective tube as he suspected. On the other hand, it's probably not the best idea to mix brands.

Skip

[carusoam]

Skip,

Any idea what the hole at the end has for an ID?

Does the fuel injector generate a spray/mist by sending the fuel through a tiny hole at the end?

From the blocked FIs... I’m guessing their is some constriction there...

Makes the blocked fuel line sound similar to having a heart attack.... 

Best regards,

-a-

[PT20J]

Just now, carusoam said:

Skip,

Any idea what the hole at the end has for an ID?

Does the fuel injector generate a spray/mist by sending the fuel through a tiny hole at the end?

From the blocked FIs... I’m guessing their is some constriction there...

Makes the blocked fuel line sound similar to having a heart attack.... 

Best regards,

-a-

Not sure what diameter the hole is. There is a calibrated restrictor within the body of the nozzle. The two components are a matched set so if you take them apart to clean them, don't mix up the pieces. Al Jesmer at Precision Airmotive told me that they don't actually calibrate the nozzles but they do flow fluid through each and can tell by eyeballing the spray pattern if it's good. The servos are calibrated on a flow bench.

Skip

[Yetti]

Well they did not have Lycoming line in stock when I ordered.   He said on the phone that the Superior was thicker.   Which I believe it to be.   If you look, the ends are smaller than ID of the line.   So I am thinking the restriction is the ends not the line itself.   That and it is a pressurized line so that changes the flow characteristics.     Also the guy that did my Servo did the servo, the flow divider and the injectors to calibrate.