After my last flight, there was blue staining on both sides at the wing root and down the gear legs. Not a huge amount, but obviously needs fixing. Had the root panels off - no signs of leak. So seats out and tunnel panels off. Sure enough, the leak seems to originate in the tunnel and flowed out across to the wing root.
I should mention now that my fuel system is modified a little. UK regs require a gascolator but with the wing fuel drains being at the low point, it's a bit redundant. A mod has been approved to remove the inline filter and put the gascolator in the tunnel to act as a fuel filter only. Using the Andair version means easy cleaning by screwing off the bowl. I also use the Andair fuel selector. All piping is standard flared aluminium fittings.
Witness stains in the tunnel indicate that the leak is from the mid-section. This is good news as if it was forward by the pump or red-cube it would be a real PITA. I know that red-cubes have been a potential source of leaks but this does not appear to be the case.
Now here's the problem - I can't find the leak. This is bad news as a tunnel leak is potentially very serious. I initially just tried the fuel valve left/right to see if anything leaked. Then I tried again with the booster pump on. Nothing..... From what I can see, the leak has to be from the selector, gascolator or maybe the inlet to the fuel pump.
Could it be that the tunnel flexing in flight is causing a joint to weep? In which case it is going to be extremely difficult to track down. I think my next step is to take her out for a high power engine run and see if I can spot any drips. Obviously, though, I did that during the initial ground tests and all was well. Other than that, I could try tightening the joints but I don't want to end up over doing it. I could take them apart, check the flares and threads, clean and re-assemble but access is a bit tight with the panel and controls in place and I don't want to make things worse.
Any advice appreciated......
I should mention now that my fuel system is modified a little. UK regs require a gascolator but with the wing fuel drains being at the low point, it's a bit redundant. A mod has been approved to remove the inline filter and put the gascolator in the tunnel to act as a fuel filter only. Using the Andair version means easy cleaning by screwing off the bowl. I also use the Andair fuel selector. All piping is standard flared aluminium fittings.
Witness stains in the tunnel indicate that the leak is from the mid-section. This is good news as if it was forward by the pump or red-cube it would be a real PITA. I know that red-cubes have been a potential source of leaks but this does not appear to be the case.
Now here's the problem - I can't find the leak. This is bad news as a tunnel leak is potentially very serious. I initially just tried the fuel valve left/right to see if anything leaked. Then I tried again with the booster pump on. Nothing..... From what I can see, the leak has to be from the selector, gascolator or maybe the inlet to the fuel pump.
Could it be that the tunnel flexing in flight is causing a joint to weep? In which case it is going to be extremely difficult to track down. I think my next step is to take her out for a high power engine run and see if I can spot any drips. Obviously, though, I did that during the initial ground tests and all was well. Other than that, I could try tightening the joints but I don't want to end up over doing it. I could take them apart, check the flares and threads, clean and re-assemble but access is a bit tight with the panel and controls in place and I don't want to make things worse.
Any advice appreciated......
Last edited: