Greg Posted April 23, 2017 Report Share Posted April 23, 2017 I want to replace my gas caps on CTLS. I ordered new caps from Aircraft Spruce. As expected they do not have the vertical vents added by flight design. My plan was to move the vents from the old caps. But I am having a problem removing the old vents from the old caps. I can loosen the nut on the upside of the cap. But the lower part of vent tube seems to be flaired in. Has anyone removed the vent tubes? Does anyone have a diagram? Will the fuel flow adequately without the vents? I appreciate any guidance. Thanks Greg Link to comment Share on other sites More sharing options...
Roger Lee Posted April 23, 2017 Report Share Posted April 23, 2017 The CTLS has vents out at the wingtips unless this is an early model and they hadn't switched yet.. If yours has the metal vent tubes sticking up out of the caps those must go back in the new ones or the tanks will not flow fuel. They're just screwed in. Grab it with a pair of vice grips or pliers and they will unscrew. Link to comment Share on other sites More sharing options...
Tom Baker Posted April 23, 2017 Report Share Posted April 23, 2017 The early CTLS did have the wing tip vents, but there was some issue with the installation. The fix was the standpipe like the CTSW into the plastic cap of the CTLS. The fix was accomplished in the field IIRC. I used to work on one of these airplanes, but it was totaled in a accident. I never had the cap apart. You might give a call to Airtime Aviation, I think they had to make the modification to the airplane I used to work on Link to comment Share on other sites More sharing options...
Greg Posted April 23, 2017 Author Report Share Posted April 23, 2017 Thank you Roger and Tom I have a November 2007 CTLS. It has both the vents at the wing tips and the verticle post vent in the gas caps. The verticle post has a nut around the post just above the surface of the gas cap. The post is threaded at this point and the nut screws down to tighten the post. The post does not appear to be threaded below this point as it will spin freely once the nut is loosened, but the post will not pull out. There has to be a backing on the bottom side to allow the nut to torque against. There seems to be a rubber and plastic fitting around the bottom end of the post, but it is inside the molded cap so you can not get a grip on it. I am going to try to send photos I do not need this vent if the wing tip vents work??? Any suggestions on how to see if the wing tip vents work? Thanks much. Greg Link to comment Share on other sites More sharing options...
Greg Posted April 23, 2017 Author Report Share Posted April 23, 2017 Photos of how the vent tube attaches. Thanks - Greg https://goo.gl/photos/bAFUcPtzhhV4NfYz6 https://goo.gl/photos/WDvtH6QzSrEcdSbW8 Link to comment Share on other sites More sharing options...
Tom Baker Posted April 23, 2017 Report Share Posted April 23, 2017 The wingtip vents on the early airplanes like yours did not work as planned. That is why the standpipe was added to fix the problem. Do not fly without the added vents. It is hard to tell from your picture, but it almost looks like a nut in the recess on the inside of the cap. What ever it is I suspect it is threaded on the end of the standpipe. Link to comment Share on other sites More sharing options...
Greg Posted April 24, 2017 Author Report Share Posted April 24, 2017 Posting this for those who may need to switch old vertical vent tubes to new SPRL gas caps on CTLS Roger and Tom were right. Surprise. The verticle vent tube does thread off. There is a nylon 6M-1 nut on the top side of molded cap and the same nut on the bottom side of molded cap. Screwing them together holds the vent tube in place. The tricky part is you can not grasp the lower nut or even see it well enough to know its a nut. You have to just keep tightening (clockwise) the top nut and it will eventually rotate the vent shaft out of the bottom nut. Drill the hole in the new cap and you are set to screw back together. Here is what the vent shafts and nuts look like without the molded cap. https://goo.gl/photos/YUz8Ev7ZmLttPTsd7 Hope this helps someone. Greg Link to comment Share on other sites More sharing options...
BravoFoxtrot Posted April 24, 2017 Report Share Posted April 24, 2017 Good information. Thanks for sharing. Link to comment Share on other sites More sharing options...
rhanson Posted April 25, 2017 Report Share Posted April 25, 2017 Good info to ponder. Here's something: if only one vent is working, how would you know that ? Does this condition prevent cross-feed as well ? RH Link to comment Share on other sites More sharing options...
FlyingMonkey Posted April 26, 2017 Report Share Posted April 26, 2017 The CTSW caps are fully threaded, it looks like the CTLS caps just use locking tabs. That's probably better, unscrewing the caps several turns is a PITA. Link to comment Share on other sites More sharing options...
Greg Posted April 26, 2017 Author Report Share Posted April 26, 2017 The 2007 CTLS fuel caps have turn and lock lever caps. The caps work well and can easily be adjusted by adjusting the bottom nylon lock nut. Early CTLS apparently had verticle vent tubes to create a small positive pressure in the tank because the vents at the wing tips did not work well. My 2007 has these verticle vents and the wing tip vents. I believe Flight Design may have later improved the fuel tank wing tip vents eliminating the need for the verticle pipe vents. You can replace the CTLS Fuel caps. They are SPRL caps. Aircraft Spruce and others offer these. Aircraft Spruce offers them as a set of cap and gas cap fitting that goes into the wing. They may sell separately, I do not know. But others do sell separately. You can also just replace the two O rings, the spring and the nylon nut. Aircraft Spruce sells this tune up kit If you have the verticle vent pipes, these will have to be moved to the new caps. I posted a photo earlier. The real problem is how Flight Design mounted the cap fittings in the wings. These are epoxied in without pins or screws/bolts. A sloppy lineman in New Orleans pried my left fitting out three years ago. There have been several reports on the forum of pilots loosing the whole system in flight. My concern was sucking fuel out, but the safety officer reported several years ago that missing caps create a negative pressure that prevents that tank from flowing. Watch the sight tubes! I have struggled for three years to get my left cap fitting to properly adhere to the wing. This joint is constantly bathed in fuel. I have recently purchased a new cap and fitting. I ruffed the fitting and base where it fits in wing. You need to use flexible epoxy as the wing flexes. This time I think I have it. But I have the parts if it comes out again. And I will check often. One more point and I will quit. Your CTLS fuel cap fitting can be loose and you will not know it if you do not wiggle by hand. Put the cap in closed and wiggle. See if the whole system is moving at the joint with the wing. If it moves at the epoxied joint, it will leak rain water here when the plane is outside. And it can detach. I hope I never post on CTLS fuel caps again. But I have gotten deep into them so call me if I can help Greg Link to comment Share on other sites More sharing options...
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