Bill.Peyton
Well Known Member
How difficult would it be to first do the ground test. that may be all you need to discover a leak.
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RV-10: Fuel Smell When Turning
- Thread starter Geico266
- Start date
Ground check
I run the boost pump before start and for run up and never even got a whiff
of fuel smell, except when over priming spills fuel down into the FAB.
I can easily plug the AN fittings forward of the firewall and run the boost pump just as I did for fuel line testing during installation.
I run the boost pump before start and for run up and never even got a whiff
of fuel smell, except when over priming spills fuel down into the FAB.
I can easily plug the AN fittings forward of the firewall and run the boost pump just as I did for fuel line testing during installation.
Bill.Peyton
Well Known Member
If you just run the boost pump with the mixture set to lean it should check the lines end to end. You may not smell it on the ground because there is no airflow through the tunnel
update
I went out and flew for 30 minutes to test a couple of scenarios.
I left the tanks half full just the way they were yesterday upon returning from my trip. As I stated earlier, the smell was quite strong on landing yesterday
as well as the 3 previous landings, each following about an hour of flying.
Started engine normal, boost pump on, taxi out, run up and take off with boost pump on. As before, no smell here whatsoever.
Flew 10 minutes away to Rio Vista for landing without boost pump.
No smell whatsoever.
Back to pattern altitude and boost pump on for landing. No smell whatsoever??? This is the part that drives me nuts.
Back to Concord, I did some slow flight, full flaps and descending at various speeds and no fuel smell here either.
At this point I had been flying about 20 minutes and went back for landing,
boost pump on about 5 miles out and sure enough as I lowered the flaps I detected a whiff of fuel again.
I will open the tunnel and check all the fittings with boost pump pressure on.
I am still at a loss as to what causes this on and off smell
All suggestions considered, thank you.
I went out and flew for 30 minutes to test a couple of scenarios.
I left the tanks half full just the way they were yesterday upon returning from my trip. As I stated earlier, the smell was quite strong on landing yesterday
as well as the 3 previous landings, each following about an hour of flying.
Started engine normal, boost pump on, taxi out, run up and take off with boost pump on. As before, no smell here whatsoever.
Flew 10 minutes away to Rio Vista for landing without boost pump.
No smell whatsoever.
Back to pattern altitude and boost pump on for landing. No smell whatsoever??? This is the part that drives me nuts.
Back to Concord, I did some slow flight, full flaps and descending at various speeds and no fuel smell here either.
At this point I had been flying about 20 minutes and went back for landing,
boost pump on about 5 miles out and sure enough as I lowered the flaps I detected a whiff of fuel again.
I will open the tunnel and check all the fittings with boost pump pressure on.
I am still at a loss as to what causes this on and off smell
All suggestions considered, thank you.
Bill.Peyton
Well Known Member
It sounds like it takes a little time before the smell appears. Before u fly again I would open up the tunnel. If there are fumes in the tunnel, a concern might be the flap motor brushes causing an ignition source. When you check the fittings make sur you look around the shaft of the fuel selector. You may have to run the pump for a while before you see or smell a leak.
Wayne Gillispie
Well Known Member
I got down inside my tunnel after my leak detector pinpointed it and there it was ...fuel built up on bottom side of fitting up inside threads first then finally after several minutes would form a drip that dripped down onto my fiberfrax insulation. No blue stains appeared in fiberfrax at the time. Use a strong flashlight and mirror.
finally!
Wayne, I have been following you on this one because it was like a mystery. Im glad you were able to find the problem. Having the fuel leak found and fixed has to be great news for you and those who fly with you.
Wayne, I have been following you on this one because it was like a mystery. Im glad you were able to find the problem. Having the fuel leak found and fixed has to be great news for you and those who fly with you.
Fuel Leak Found
Although I had my doubts about a possible fuel leak, I finally opened the tunnel and was a bit shocked at what I found.
I did not take long to find the spot on th rear of the red cube where the nipple is weeping just enough to create a glossy spot after about 2 minutes of applying pressure to the lines. I could not readily see the blue stain, only now looking at the picture it's actually pretty obvious.
The aircraft has 64 hours at this time and most likely had this leak from the beginning. The fact that it was weeping just a tiny bit is probably why I couldn't smell anything on short flights. A small change in cabin pressure upon entering the pattern and applying flaps was all it took to have the vapors exit the tunnel and into the cabin, I presume.
I do know that moving the vents reduced the smell significantly from what it was before.
Thanks for all the help, I hope this is the end of fuel smells.
Question: How do you clean up the blue stain?
I tried acetone and WD40 without much success.
Although I had my doubts about a possible fuel leak, I finally opened the tunnel and was a bit shocked at what I found.
I did not take long to find the spot on th rear of the red cube where the nipple is weeping just enough to create a glossy spot after about 2 minutes of applying pressure to the lines. I could not readily see the blue stain, only now looking at the picture it's actually pretty obvious.
The aircraft has 64 hours at this time and most likely had this leak from the beginning. The fact that it was weeping just a tiny bit is probably why I couldn't smell anything on short flights. A small change in cabin pressure upon entering the pattern and applying flaps was all it took to have the vapors exit the tunnel and into the cabin, I presume.
I do know that moving the vents reduced the smell significantly from what it was before.
Thanks for all the help, I hope this is the end of fuel smells.
Question: How do you clean up the blue stain?
I tried acetone and WD40 without much success.
Bill.Peyton
Well Known Member
Ernst,
So glad you found the issue. Fuel leaks are dangerous as others have found out. having the high pressure pump inside the passenger compartment is one of the design flaws that continues to bother me. I have debated on putting the pump on the firewall in the engine compartment. I believe that the flap motor and gas fumes should not live in the same space. The West Marine fuel leak detector is probably a very good alternative. Be glad you caught it before it became a real emergency issue. Your continued diligence in the pursuit of the smell is to be commended.
While you are working in the tunnel you might consider securing your wiring separate of your fuel and brakes lines with Adel clamps or equivalent. Using cable ties on the soft aluminum to secure the wires may cause you problems down the road.
BTW I use 100LL to remove fuel stain on my vent overflow. It seems to work well. Congrats on finding the problem!
So glad you found the issue. Fuel leaks are dangerous as others have found out. having the high pressure pump inside the passenger compartment is one of the design flaws that continues to bother me. I have debated on putting the pump on the firewall in the engine compartment. I believe that the flap motor and gas fumes should not live in the same space. The West Marine fuel leak detector is probably a very good alternative. Be glad you caught it before it became a real emergency issue. Your continued diligence in the pursuit of the smell is to be commended.
While you are working in the tunnel you might consider securing your wiring separate of your fuel and brakes lines with Adel clamps or equivalent. Using cable ties on the soft aluminum to secure the wires may cause you problems down the road.
BTW I use 100LL to remove fuel stain on my vent overflow. It seems to work well. Congrats on finding the problem!
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Try MEK. Glad you found it. I had my suspicions. Now I hate to pick, but I do see 2 things. First, I'd prefer not to see any wiring lashed to fuel lines. Even if its isolated like I see there. Its more better to route the wiring together and adel it to the tunnel side ABOVE the lines. You did just have a fuel leak there after all. I'll let somebody else catch the other thing. Its not a big thing. Sorry, couldn't hold it.
Speak up
aerhed,
speak up, I've been following everybody's advise so far.
It's not personal, I am first and foremost interested in a safe airplane.
I don't see much harm, short or long term in tying a couple of wires to an aluminum line when properly isolated with 1/4 " rubber hose. It's an extremely difficult spot to reach for properly securing adel clamps, so I opted for rubber hose and zip ties.
Whatever else you see please point it out.
The kind of slow weeping leak would have never been detected, had this occurred in the engine compartment. I've had the very same fuel system installation in my RV-8 and with white interior paint never saw or detected any fuel stains.
However, all of the installation was exposed and visible up to the firewall.
In the 10, it is confined and not very accessible for inspection.
I have been diligent in applying proper torque values and from what I see,
this nipple simply needs another 1/4 turn to make it tight, effectively over torquing it just a bit. I am well aware of the effect of over torquing AN tube fittings but NPT threads just need a little more than the prescribed conventional torque value. As to having the high pressure fuel pump inside the cockpit, I don't see a benefit in having the high pressure boost pump up front. A leak in the firewall forward compartment is probably much worse than one in the cabin were you can smell it and apart from the flap motor no other ignition source exists. I deliberately put all these components including BP, flow meter and pressure sender behind the firewall to keep it on the cool side. I run mogas out of the right tank and keeping the fuel system cool is one way to prevent vapor lock.(another thread)
The fuel leak detector seems like a great idea, at least until you know the system is tight. It is quite a chore to open up the tunnel and get a good look at the fuel lines. Your nose can tell the truth too apparently.
aerhed,
speak up, I've been following everybody's advise so far.
It's not personal, I am first and foremost interested in a safe airplane.
I don't see much harm, short or long term in tying a couple of wires to an aluminum line when properly isolated with 1/4 " rubber hose. It's an extremely difficult spot to reach for properly securing adel clamps, so I opted for rubber hose and zip ties.
Whatever else you see please point it out.
The kind of slow weeping leak would have never been detected, had this occurred in the engine compartment. I've had the very same fuel system installation in my RV-8 and with white interior paint never saw or detected any fuel stains.
However, all of the installation was exposed and visible up to the firewall.
In the 10, it is confined and not very accessible for inspection.
I have been diligent in applying proper torque values and from what I see,
this nipple simply needs another 1/4 turn to make it tight, effectively over torquing it just a bit. I am well aware of the effect of over torquing AN tube fittings but NPT threads just need a little more than the prescribed conventional torque value. As to having the high pressure fuel pump inside the cockpit, I don't see a benefit in having the high pressure boost pump up front. A leak in the firewall forward compartment is probably much worse than one in the cabin were you can smell it and apart from the flap motor no other ignition source exists. I deliberately put all these components including BP, flow meter and pressure sender behind the firewall to keep it on the cool side. I run mogas out of the right tank and keeping the fuel system cool is one way to prevent vapor lock.(another thread)
The fuel leak detector seems like a great idea, at least until you know the system is tight. It is quite a chore to open up the tunnel and get a good look at the fuel lines. Your nose can tell the truth too apparently.
Bill.Peyton
Well Known Member
I installed access panels on the side, which makes it very easy to open up the tunnel and get access to the filter etc. I think someone is actually selling a kit for this, or you can make your own. I installed an Aerosport center console ans inst panel, which really complicates opening the tunnel from the top
In regards to the wires, you could also use the adhesive backed anchors that are available in the aviation section of your local big box store.
In regards to the wires, you could also use the adhesive backed anchors that are available in the aviation section of your local big box store.
Check AC43.13 11-96(w) and 11-118(a) for routing near fluid lines and drip loops. Then stare at your wiring and think about what could happen with fuel leaks and pump vibration. The other little thing was the torque seal. It really should stretch from the B-nuts, over the threads, and onto the fitting its attached to. As you have it, its possible for a nut and ferrule to turn together without breaking the seal. Not likely, but possible. A broken seal should essentially indicate movement between two fittings.
Agreed
I have to agree with both of your points, drip loop and separation between fuel lines and wiring especially the one going to the fuel pump. The signal wires coming from the pressure sender should not be a concern.
I applied inspection laquer mostly as a visual measure to know wich nuts had been tightened during installation but extending the bead of laquer across the nut ferrule and tube would certainly help in detecting movement at inspection time.
I did look at installing an access panel on each side but came away unconvinced. While these access panels will allow you to somewhat inspect the tunnel area it will be almost impossible to actually do anything in that awkward low position. Especially when it comes to fuel lines or filterts, you need 2 wrenches to open and properly close a B-nut, you need good lighting
and a good visual on the work area.
Without the top cover open you will have your head a foot lower than your rump section, squeezed between rudder pedals and the stick while trying to see what you are doing, applying proper torque and securing 2 adel clamps
and many other tasks. Before I took the picture I had also removed the rear heater hose to gain some working space, imagine reaching the firewall to undo the clamp from those access panels.
I am 5'6" 150lb and usually not terribly uncomfortable doing things upside down but I can't possibly imagine how I would be able to tighten that nipple
without the entire cover off.
In hindsight, I wanted to believe that the vents were the problem in part because it was easier to fix.
I do like the look of the center console but be sure to make installation and removal as easy as possible with plugs for electrical connections etc.
I have to agree with both of your points, drip loop and separation between fuel lines and wiring especially the one going to the fuel pump. The signal wires coming from the pressure sender should not be a concern.
I applied inspection laquer mostly as a visual measure to know wich nuts had been tightened during installation but extending the bead of laquer across the nut ferrule and tube would certainly help in detecting movement at inspection time.
I did look at installing an access panel on each side but came away unconvinced. While these access panels will allow you to somewhat inspect the tunnel area it will be almost impossible to actually do anything in that awkward low position. Especially when it comes to fuel lines or filterts, you need 2 wrenches to open and properly close a B-nut, you need good lighting
and a good visual on the work area.
Without the top cover open you will have your head a foot lower than your rump section, squeezed between rudder pedals and the stick while trying to see what you are doing, applying proper torque and securing 2 adel clamps
and many other tasks. Before I took the picture I had also removed the rear heater hose to gain some working space, imagine reaching the firewall to undo the clamp from those access panels.
I am 5'6" 150lb and usually not terribly uncomfortable doing things upside down but I can't possibly imagine how I would be able to tighten that nipple
without the entire cover off.
In hindsight, I wanted to believe that the vents were the problem in part because it was easier to fix.
I do like the look of the center console but be sure to make installation and removal as easy as possible with plugs for electrical connections etc.
Geico266
Well Known Member
Well I think I may have found the problem with fuel smell whiloe turning base to final. During the just completed condition inspection I found 3 fuel related issues that may have been the problem, but having fixed all 3 at once I don't know which one it was.
1. A leaking fitting on the fuel return line inside the tunnel. There were fuel stains stain on the fitting and line, but no fuel on the floor. The fitting was loose so I torqued it up.
2. I then replaced the fuel caps after reading there are two style of caps and two sets of o-rings that are not interchangeable, I did not know which o-rings go with which caps so I just replaced them as the old ones leaked. The new ones are water tight and no fuel escapes on steep climb out with full tanks anymore.
3. The vent tubes had small holes drilled in the back side. I sealed those up.
So between the new fuel caps, tighten the tunnel fitting, sealing the extra hole in the vent tubes...... NO MORE FUEL SMELL!
Thanks to all that responded, just thought I would post what I think fixed my smelly issue.
1. A leaking fitting on the fuel return line inside the tunnel. There were fuel stains stain on the fitting and line, but no fuel on the floor. The fitting was loose so I torqued it up.
2. I then replaced the fuel caps after reading there are two style of caps and two sets of o-rings that are not interchangeable, I did not know which o-rings go with which caps so I just replaced them as the old ones leaked. The new ones are water tight and no fuel escapes on steep climb out with full tanks anymore.
3. The vent tubes had small holes drilled in the back side. I sealed those up.
So between the new fuel caps, tighten the tunnel fitting, sealing the extra hole in the vent tubes...... NO MORE FUEL SMELL!
Thanks to all that responded, just thought I would post what I think fixed my smelly issue.
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