Flying C Farms Posted February 15, 2012 Report Share Posted February 15, 2012 Have recently replaced my o-rings on the CTSW fuel caps. The invoice from Flight Design says they replace C9997730H. Has anyone else replaced these and do you have trouble opening the fuel caps as it feels like metal to metal contact and make a pop when opening(breaking it loose). The good news is so far have not noticed any fuel stains and will be able to test the breaking strength of the fuel dip guage. There has to be a simple reason why both tanks hold 17 with 16.5 useable, but the dip guage is has different markings for each side. Thank you for your imput. Link to comment Share on other sites More sharing options...
chanik Posted February 15, 2012 Report Share Posted February 15, 2012 Have recently replaced my o-rings on the CTSW fuel caps. The invoice from Flight Design says they replace C9997730H. Has anyone else replaced these and do you have trouble opening the fuel caps as it feels like metal to metal contact and make a pop when opening(breaking it loose). The good news is so far have not noticed any fuel stains and will be able to test the breaking strength of the fuel dip guage. There has to be a simple reason why both tanks hold 17 with 16.5 useable, but the dip guage is has different markings for each side. Thank you for your imput. I used these Fluocarbon orings http://ctflier.com/index.php?/topic/646-ls-gas-caps/page__view__findpost__p__4114 They are industructable, but not super soft. I use a bit of fuel-proof grease on the seal so that they don't leak at all when I'm topped off. Link to comment Share on other sites More sharing options...
DocRon Posted February 15, 2012 Report Share Posted February 15, 2012 I need to try this myself. I replaced the right wing fuel cap o-ring and it still leaks fuel across the wing. If you guys have found a dependable o-ring that really works I've got to try it. Link to comment Share on other sites More sharing options...
chanik Posted February 15, 2012 Report Share Posted February 15, 2012 The trickier thing was to find fuel-proof grease. It still leaked slightly when the fuel tanks were very full with the new o-rings. The previous rings were decaying/softening and leaking alot though. Link to comment Share on other sites More sharing options...
Admin2 Posted February 15, 2012 Report Share Posted February 15, 2012 Many of us don't fuel more than 15 gal. Unless you need to fly a very long leg with no available fuel 15 gal. Is usually more than plenty. Link to comment Share on other sites More sharing options...
Runtoeat Posted February 15, 2012 Report Share Posted February 15, 2012 DocRon, just a sanity check. Although the "O" ring is the "normal" source for leaks, you may be leaking fuel from the putty that seals the gap around the filler fixture that accepts the fuel filler? After 20 to 30 hours, I notice a fuel stain which runs from the fuel filler and forms a yellow stain rearward to the trailing edge of my flap. The fuel is not coming from the "O" ring on my CTSW but is coming from leaks at the gap around the filler fixture. If the normal brown colored putty that seals the fixture has areas that are turning black and small gaps at the interface of the putty to the wing, you may be leaking here. This has been reported by other CTSW owners. If the filler fixture is leaking, the CTSW has a gasket which seals the filler fixture which must be replaced and the putty sealer reapplied. If you are still getting fuel stains after replacing the "O" ring, this may be your problem. Link to comment Share on other sites More sharing options...
sandpiper Posted February 15, 2012 Report Share Posted February 15, 2012 I carry a maximum 25 gallons unless more is needed but that's rarely. I get my fuel cap o rings at Tru-Value. I have only had to replace them once in 5 years. Link to comment Share on other sites More sharing options...
chanik Posted February 15, 2012 Report Share Posted February 15, 2012 I leave 34Gal in the tanks frequently. The lack of air inhibits gum formation and condensation and I do like to fly 6hr+ legs. It's a problem with any sort of parking tilt once you fill above 25Gal too. Link to comment Share on other sites More sharing options...
kentuckynet Posted February 16, 2012 Report Share Posted February 16, 2012 I have never seen it leak form around the oring, it leaks out of the vent which is just above! Atleast thats how it cam eout of mine and thats where i saw it coming out of flying c farms plane. mack Link to comment Share on other sites More sharing options...
chanik Posted February 16, 2012 Report Share Posted February 16, 2012 The vent openning is ~3" higher than the cap. I've never had it sit so tilted that it flowed out there, I think Link to comment Share on other sites More sharing options...
Tom Baker Posted February 16, 2012 Report Share Posted February 16, 2012 The vent openning is ~3" higher than the cap. I've never had it sit so tilted that it flowed out there, I think Do you block your gear when you park the airplane in case of a flat tire? Full tanks and a flat will leave you a big mess. Link to comment Share on other sites More sharing options...
kentuckynet Posted February 16, 2012 Report Share Posted February 16, 2012 Chanik, each time o have been to page someone in the group was called back to there aircrafts due to fuel pouring out the vents. Roger up until last year always had up park our planes at page sideways just to avoid this known issue with all ctsw's. There have been many posts about check valves and the possibility of adding a fuel selector switch to avoid these type issues. If you fill your tanks full annd your plane is just off a little or even a low tire fuel pous out the vents. Whe i take off with full fuel and the planes leans one way or the other there will be fuel all over the wing. mack Link to comment Share on other sites More sharing options...
DocRon Posted February 16, 2012 Report Share Posted February 16, 2012 DocRon, just a sanity check. Although the "O" ring is the "normal" source for leaks, you may be leaking fuel from the putty that seals the gap around the filler fixture that accepts the fuel filler? After 20 to 30 hours, I notice a fuel stain which runs from the fuel filler and forms a yellow stain rearward to the trailing edge of my flap. The fuel is not coming from the "O" ring on my CTSW but is coming from leaks at the gap around the filler fixture. If the normal brown colored putty that seals the fixture has areas that are turning black and small gaps at the interface of the putty to the wing, you may be leaking here. This has been reported by other CTSW owners. If the filler fixture is leaking, the CTSW has a gasket which seals the filler fixture which must be replaced and the putty sealer reapplied. If you are still getting fuel stains after replacing the "O" ring, this may be your problem. Dick, I'll definitely check this. Another reason why this forum is so good to read. I really benefit from the experiences of all the contributors. I just ordered new flurocarbon 0-rings (also recomended here) and will check the putty around the filler fixture. I also try (now, anyway) not to fill the right tank too full. I keep learning! Link to comment Share on other sites More sharing options...
chanik Posted February 16, 2012 Report Share Posted February 16, 2012 I had the problem while flying on topped off tanks. I figure, now it has 3 more inches to climb before it gushes out so that seems to mitigate any further stains so long as I keep it fairly level for the first hour of flight. Simple geometry would show a flat would raise the fuel about 6-8" in the dropped wing so that would surely spill everywhere. I'll have to keep that in mind. Link to comment Share on other sites More sharing options...
sandpiper Posted February 16, 2012 Report Share Posted February 16, 2012 I always put blocks below the axles when parked in the hangar. Since it is attached to our house, a fuel spill could ruin my day. Link to comment Share on other sites More sharing options...
Brucegoose Posted February 20, 2012 Report Share Posted February 20, 2012 I replaced my "O" rings four years ago. I simply took one cap with the "O" ring on with the diameter of the filler to a local seal specialist and they recomended I change to Viton rubber. Have not had a leak or deterioation of the rubber since. Regards Bruce Link to comment Share on other sites More sharing options...
chanik Posted February 20, 2012 Report Share Posted February 20, 2012 Viton, BTW, is just a brand of fluorocarbon elastomer so any such o-ring will basically outlast the plane. It's become eponymous though, much like xerox, frisbee, zipper or thermos. Link to comment Share on other sites More sharing options...
wlfpckrs Posted April 10, 2012 Report Share Posted April 10, 2012 Do the 2006 CTSW and CTLS use the same o-rings? Link to comment Share on other sites More sharing options...
Tip Posted April 10, 2012 Report Share Posted April 10, 2012 Don, The SW and LS are different. If you needs o rings, I have some for the SW. Link to comment Share on other sites More sharing options...
Philip Welsch Posted April 11, 2012 Report Share Posted April 11, 2012 Aircraft Spruce sells the caps and the o-rings used on the LS (2008 at least). PRW Link to comment Share on other sites More sharing options...
wlfpckrs Posted April 11, 2012 Report Share Posted April 11, 2012 Tip, I could use a couple o-rings for the SW. Where did you get yours, and how much would they cost? Do you have a part number or the specs? Do you have the viton/fluorocarbon o-rings? Link to comment Share on other sites More sharing options...
Runtoeat Posted April 11, 2012 Report Share Posted April 11, 2012 Hi Tip. I could stand to replace my original "O" rings. What is the material and size of the CTSW "O" rings you have? Link to comment Share on other sites More sharing options...
Tip Posted April 11, 2012 Report Share Posted April 11, 2012 I had this problem until I switched to Viton. From my old post: I run E10 almost exclusively. Can't say I've seen any problems except the gas cap o-rings. It's also worth changing the fuel filter every 100hrs instead of 200hrs I think. Could have just been age, but anyway I replaced them with VITON style rings: Product ID: ov-75-222 Product Name: Fluorocarbon 222 Size O-ring Quantity: 2 Unit Price: $0.64 from http://www.superiorseals.com/ Pretty solid now. This is where I bought them. I'll check at the airport to see how many I have. Link to comment Share on other sites More sharing options...
Roger Lee Posted April 11, 2012 Report Share Posted April 11, 2012 Viton "O" rings are what's listed in the parts manual. Looks like everyone is good to go with Tip's info. Thanks Tip Link to comment Share on other sites More sharing options...
chanik Posted April 12, 2012 Report Share Posted April 12, 2012 The only other advice I have is that I use a thin coating of Krytox grease on the rings so that they are virtually hermetic. That way fuel doesn't leak out at all and stain the filler neck area even when I'm very topped off. Link to comment Share on other sites More sharing options...
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