Wing root fuel leak [UPDATE]

[EB3]

Hello everyone, I haven't posted in a long time, just lurked. Now I have reason to post. I was doing a walk-around my CTLSi last weekend and discovered a slight fuel leak at the right wing root. The leak appears to be between the root and the fuselage. I've ruled out a leak from the sight tube, also cannot detect any trace of fuel by running paper towels in the space above the passenger door inside the fuselage (where fuel and electrical lines run). There's not a strong fuel odor inside the cabin.

I jammed a paper towel into the little gap where the wing joins the fuselage (see red arrow) and the paper towel gets a little damp from fuel from that gap. What might be leaking in there? And will the wing need to be pulled back to access making a repair (I'm thinking that's the only way to get to it)? 

No, I do not intend on pulling a wing alone or even with my local A&P (he's never worked on FDCT). I'd have to ferry it somewhere.

I'd be grateful for any insight, thank you. 

[Anticept]

That's where the sight tube, inspection panel, and fuel hose comes from.

It can also show up there from spilling fuel on top of the wing.

Gonna have to do a pull to investigate if you cant see it from the inside with an inspection mirror.

[Roger Lee]

I’m about 98% sure that since this is a CTLSi that the leak is from where the fuel line is clamped onto the wing tank fitting. It’s easy to fix. Drain the fuel and pull that wing only out about 1-1.5” so you have access to that hose and clamp and reclamp it. Since the metal fitting there is quite short make sure you push the hose on all the way and when pushing the wing back on make sure you don’t pull it outward once clamped.
 

[Tom Baker]

I'm with Roger on the location. The hose connection is right above that. It certainly could be the hose, but it could also be the fitting in the wing. I also heard of a CTLSi having a fitting that had some porosity and it was actually the fitting that was leaking. 

[Roger Lee]

The way I pull the wing on a CTLSI is after I drain the fuel I remove the back header cover above the storage shelf area. Then disconnect the rubber fuel lines that connect to the metal ones. They are only clamped on.  Than when I slide the wings out I don’t have to worry about messing with the fuel hose attached at the fuel bulkhead and it stays firmly clamped. In the CTLS it’s different.

[Mike Koerner]

EB3,

Be sure you check the fuel fittings on your left wing too. As I had posted some time back, it's possible for the fuel to run across the spar tube. A leaking fitting on the left side can show up as a leak from the right wing root as shown in your photo.

Mike Koerner

[EB3]

On 7/25/2022 at 7:25 AM, Roger Lee said:

The way I pull the wing on a CTLSI is after I drain the fuel I remove the back header cover above the storage shelf area. Then disconnect the rubber fuel lines that connect to the metal ones. They are only clamped on.  Than when I slide the wings out I don’t have to worry about messing with the fuel hose attached at the fuel bulkhead and it stays firmly clamped. In the CTLS it’s different.

Questions:

1) Is the wing installation/removal procedure the same for the CTLSi as the CTLS (per the Maintenance & Inspection Procedures Manual for the CTLS)?

2) Is the Main Bolt for the wing being pulled (the right side in my case) the only one that needs to be removed, or must both Main Bolts (right & left) need removal? My A&P thinks both may need to be removed, but we want to clarify.  

Thank you! 

 

[Anticept]

Both. They pin together the carry through spars. Make sure BOTH wings are supported or you will seriously damage the aircraft.

[EB3]

15 minutes ago, Anticept said:

Both. They pin together the carry through spars. Make sure BOTH wings are supported or you will seriously damage the aircraft.

OK, thanks - that makes sense. Yes, we have supports under both wings. During my search for "Wing Removal" on this site, I'd seen using support for both wings mentioned several times.

[Tom Baker]

Drain the fuel. For the CTLSi I disconnect the fuel line from the fuel rail on the left side and use the fuel pump to drain the fuel. Turn on the master, back up power, and fuel pump on. Support both wings. Remove caps from wing pins. I tape the aileron and flaps to keep them from dropping. One strip across the aileron gap, and two for the flaps. Remove the bolt for the aileron bell crank in the wing root. Pull the pins. Slide the wing out just a little 1.5 to 2 inches. Unhook the fuel line from the wing root. Slide the wing out a little more 5-6 inches. Disconnect fuel vent line, pitot line, AoA line, and wiring. Once everything is disconnected then you can slide the wing out completely. I normally set them on saw horses with a two by four piece of 1" pink foam. The saw horses need to be 100" apart. The other wing can remain in place as long as it is supported. If you have to remove the left wing in has an extra fitting at the top towards the rear. It is a flare fitting that takes a 17mm wrench.

[EB3]

This morning we got the wing pulled back enough to expose the clamp and, sure enough, that was causing the leak. He replaced it with a better grade of clamp and after some jiggling and wiggling, got the wing back in place and both main bolts reinstalled and torqued and everything else. Took about two hours in total. Seems to be holding fuel OK now.

Thanks for everyones' advice! 

[Anticept]

Big tip, look up there in the wing from inside and verify the hose is not kinked.

I find more often than not that I have to put a spring inside the hose to prevent kinking.

Exterior springs are acceptable if you can find one of the right size.

[Tom Baker]

16 minutes ago, Anticept said:

Big tip, look up there in the wing from inside and verify the hose is not kinked.

I find more often than not that I have to put a spring inside the hose to prevent kinking.

Exterior springs are acceptable if you can find one of the right size.

The CTLSi is a little different than the CTLS, the hoses on the CTLSi go to the rear instead of down the door post. Both need help to keep the hose from kinking.

[Anticept]

That one I actually knew!

[EB3]

On 8/24/2022 at 3:29 PM, Anticept said:

Big tip, look up there in the wing from inside and verify the hose is not kinked.

I find more often than not that I have to put a spring inside the hose to prevent kinking.

Exterior springs are acceptable if you can find one of the right size.

I went back to the hangar this morning, and now the SOB is leaking again. There wasn't any evidence (stains, etc.) that fuel was leaking from anywhere but where the hose clamps to the fitting at the wing root. My A&P used a better grade of clamp, and everything went back together relatively easy. I'm now wondering if the hose itself might have a leak in that area. Replacing the hose will be a booger since it has to thread under the spar. The spring idea to prevent kinking is a good one, but I have a feeling I'll have to convince my A&P that's a bona fide option. 

[Roger Lee]

Call me. I can tell you a better way to do this and make sure everything seals.

520-349-7056.

[EB3]

Will do, Roger. If I can get my guy back to my hangar next week, we will give you a call. Thanks! 

[EB3]

We finally got the right  wing pulled back again to examine the hose and fitting at the root. This time we crimped-off a section of hose, refilled the tank just enough to cover up the fitting. Due to the gunk and stains around the fitting, we suspected the leak wasn't from the hose, but from the fitting. Sure enough, after a few minutes, wetness was noticed at the bottom of the fitting. That's the source of the leak. See photos attached.

What's the likely culprit - any ideas? The fitting has a nut at the base - does that simply need to be tightened? I can only wish it's that easy. Also, there appears to be a crack, but not sure if it's truly a crack or just where excess material was smeared when the wing was built. we don't see any evidence of fuel accumulating inside the wing root (there's a nearby drain hole under the wing with zero stains). 

 

[Anticept]

I believe the fittings have sealant around them and sandwich the composite. If so, it will require you to open the wing to get to the other side. However, I have never removed a fitting before, and mine looks a little different, so please do call roger or airtime.

[Tom Baker]

I had one of these leak before. Arian told me to take the nut off and seal it with marine epoxy, and reinstall the nut into the wet epoxy. I did that, and then re did it to finally seal that leak. I think a better solution might be to bevel the inside of the nut, and place a small o-ring over the fitting captured by the bevel on the nut. There should be no need to remove the cover unless the fitting turns. The one I did the fitting was glued into the wing.

[TheEngineer]

Curious how 

On 10/26/2022 at 2:35 PM, EB3 said:

We finally got the right  wing pulled back again to examine the hose and fitting at the root. This time we crimped-off a section of hose, refilled the tank just enough to cover up the fitting. Due to the gunk and stains around the fitting, we suspected the leak wasn't from the hose, but from the fitting. Sure enough, after a few minutes, wetness was noticed at the bottom of the fitting. That's the source of the leak. See photos attached.

What's the likely culprit - any ideas? The fitting has a nut at the base - does that simply need to be tightened? I can only wish it's that easy. Also, there appears to be a crack, but not sure if it's truly a crack or just where excess material was smeared when the wing was built. we don't see any evidence of fuel accumulating inside the wing root (there's a nearby drain hole under the wing with zero stains). 

 

Curious how this turned out for you. Did you bed the nut in epoxy as was suggested in the thread? I believe I have the same problem right now with my CTLSi.

[EB3]

On 1/19/2023 at 8:15 AM, TheEngineer said:

Curious how 

Curious how this turned out for you. Did you bed the nut in epoxy as was suggested in the thread? I believe I have the same problem right now with my CTLSi.

Sorry for the delayed reply. The local A/P simply tightened up the nut, but also used some sort of fuel-resistant thread sealant. It's like an epoxy of sorts in that it comprised two parts to be mixed in exact ratio. It worked, but IMO he over-thought the whole thing as far as which sealant was OK to use, IMO. By the time I figured out (with help from this forum) what needed to be done, he was already elbow-deep. I didn't want to rock the boat because he's my only option if I need maintenance. I do not want to burn that bridge.

It's been a big clusterf**k. Makes me highly question my continuation with aviation - I'm at a crossroads with that. At this point, it's not worth the hassle.

 

[Madhatter]

2 hours ago, EB3 said:

Sorry for the delayed reply. The local A/P simply tightened up the nut, but also used some sort of fuel-resistant thread sealant. It's like an epoxy of sorts in that it comprised two parts to be mixed in exact ratio. It worked, but IMO he over-thought the whole thing as far as which sealant was OK to use, IMO. By the time I figured out (with help from this forum) what needed to be done, he was already elbow-deep. I didn't want to rock the boat because he's my only option if I need maintenance. I do not want to burn that bridge.

It's been a big clusterf**k. Makes me highly question my continuation with aviation - I'm at a crossroads with that. At this point, it's not worth the hassle.

 

If you plan on staying in aviation and have the time, make an effort to learn how to do things for yourself by getting the training, engine,  airframe, etc. Talk to Roger about it. It will be worth it. Most good A&P's today are either owners of a legitimate maintenance business or work for a good paying maintenance business. Most of the rest are worthless and you need to be able to know more about your aircraft than they do. It's not hard, most of it is common sense. I've been in this environment for a long time and things are not good. So bad that repair stations are hiring good car mechanics and retraining them to work on aircraft. I see this every day as I am connected with a large repair station.

When I decided to fly I knew I had to be able to do anything on any aircraft including avionics. I however went a little overboard on aviation training but it serves me well. 

[Jim Meade]

In my experience, the best training is provided by Bryan and Carol Carpenter of Rainbow Aviation.

[FlyingMonkey]

On 2/1/2023 at 6:54 PM, EB3 said:

Sorry for the delayed reply. The local A/P simply tightened up the nut, but also used some sort of fuel-resistant thread sealant. It's like an epoxy of sorts in that it comprised two parts to be mixed in exact ratio. It worked, but IMO he over-thought the whole thing as far as which sealant was OK to use, IMO. By the time I figured out (with help from this forum) what needed to be done, he was already elbow-deep. I didn't want to rock the boat because he's my only option if I need maintenance. I do not want to burn that bridge.

It's been a big clusterf**k. Makes me highly question my continuation with aviation - I'm at a crossroads with that. At this point, it's not worth the hassle.

 

Sorry to hear you had so much trouble with it.  I echo what Madhatter and Jim said, you can learn to do most tasks yourself.  If you are handy I'd suggest an ELSA conversion.  They you can do any maintenance you feel comfortable performing, and if you take a weekend course you can do your own conditionals as well.  Doing that plus asking lots of questions on this forum has saved me thousands of dollars and many hours of finding and waiting on qualified mechanics to do maintenance.  You'll also learn your airplane inside-out.

The Rainbow course is said to be outstanding, I'm considering that one.