procharger Posted January 21, 2016 Report Share Posted January 21, 2016 I was looking at some of my old posts and noticed there were over 3800 views on this subject, any one else had any tank drain issues lately, yea I am bored to cold to fly here. Snow on the way on east coast. Link to comment Share on other sites More sharing options...
Anticept Posted January 21, 2016 Report Share Posted January 21, 2016 Irregular drain is extremely common. Even in cessnas, it's hit or miss for even draining. The biggest issues causing irregular draining is uncoordinated flight. If the inclinometer installation is not level with the aircraft in flight, you will fly one wing low. Second biggie is unbalanced pressure, caused by a clogged fuel tank balance tube or tank vent clog/misalignment. Link to comment Share on other sites More sharing options...
rhanson Posted January 22, 2016 Report Share Posted January 22, 2016 As a new CT member, I am adjusting to this fuel imbalance problem; lately, I only have to fill the left tank. As I am parking outdoors on a slope, the left is higher than the right wing, and I am advised that this configuration will keep the right tank full. However I cannot be sure that I am using any fuel from the right wing, and now Anticept refers to: " unbalanced pressure, caused by a clogged fuel tank balance tube or tank vent clog/misalignment" to be concerned with. How do you troubleshoot this problem without running the left tank dry ? Thanks, Ron P52 Link to comment Share on other sites More sharing options...
Anticept Posted January 22, 2016 Report Share Posted January 22, 2016 It is extremely unlikely to have those vents or balance line clog. I should have been more clear: that's a cause of unbalanced draining, but for how often there are actual occurrences? I can really only think of two reasons this would crop up: maintenance induced failure, and insects. I believe many SW's don't even have a balance line. If you can blow compressed air into the vent with the fuel cap off, you aren't clogged. Just don't go crazy and blow high pressure into it. A bike pump is fine. In reality, unless you consistently run low on fuel and slip to landings, you're not going to have a problem. (note: forward slipping does unport fuel, so if you're low, don't do it!) In pretty much all cases with CTs that I know of, it's because of rudder trim dropping the right wing slightly trying to center the ball. The inclinometer install is often a couple degrees off center. Link to comment Share on other sites More sharing options...
Roger Lee Posted January 22, 2016 Report Share Posted January 22, 2016 I did the research (with the old vents and other vents, with negative and positive pressure vents) on this back in May 2007. This is not a pressure issue at all. It is the flat tank design and the fact that many instrument panels and instruments are not perfectly aligned for flight so you may be slightly out of trim which will cause this effect. This is not just CT's, but also in the certified world with certain aircraft. My left tank also drains faster. I fly 1/2 ball out to the left and my tanks drain equally. Remember this: The fuel will follow the ball. That means if you want to transfer fuel from the right tank to the left or feed more off the right then fly with the ball 1/2 out to the left. Put the ball always out towards the low fuel wing and fuel from the other tank will not only feed the engine, but will also transfer to the other wing. I never park on a slope with a wing low because our fuel system between wings are open and not closable. That means fuel from the high wing will flow to the low and it will overflow out the low wing vent. One last comment. There is no reason to ever fly with so little fuel in the wings as to be almost empty and some who have done this and not understood fuel flow have had engine outs. There is no reason to fly with excessively low fuel. Link to comment Share on other sites More sharing options...
Aero-Nut Posted January 22, 2016 Report Share Posted January 22, 2016 I would think since the tanks are basically connected together with a "T" fitting that even if one tank runs dry you will still get fuel from the other as gravity of the fuel will prevail over air. That is assuming that your venting system or fuel lines are not plugged. Link to comment Share on other sites More sharing options...
Roger Lee Posted January 22, 2016 Report Share Posted January 22, 2016 You are correct unless the other tank is somewhat low on fuel and you unport that fuel to the outside of the that tank effectively remove that fuel from use. Then both tanks are effectively empty to the engine. This has been done and caused some off field landings. I never ever short myself of fuel regardless of weight. Fuel is your elixer of life while flying so running out should never happen and if you do make a bad decision then it's time to land and top off. Why put yourself in a predicament when it's so easily avoidable. Link to comment Share on other sites More sharing options...
Tom Baker Posted January 22, 2016 Report Share Posted January 22, 2016 The CTSW has the vents on top of the fuel cap. They are easy to check. One thing to watch is that the hood on the pipe is pointed the correct direction. If it still has the green dot it should be forward. The CTLS changed to vent in the winglets with little NACA scoops. these vents are connected to the tanks and also incorporate a cross over tube to help equalize pressure. there is a "T" fitting connection forward of the little clear cover on the wing where the individual lines can be checked. I did hear of one airplane having one of the vent line disconnected and having fuel flow issues. On the very first CTLS's that were delivered they had more extreme fuel flow issues, and they added a standpipe like used on the CTSW. I think they used to small diameter lines on the early airplanes IIRC. The other thing with both airplanes is to check the feed lines from the wings to the engine. If a line is a little restricted by having to tight of a radius somewhere it will cause that tank to drain slower. As long as the flow from each tank is sufficient to run the engine I wouldn't worry to much about a restriction. Link to comment Share on other sites More sharing options...
FredG Posted January 22, 2016 Report Share Posted January 22, 2016 As has been mentioned previously, there are two separate mechanisms that can lead to unequal fuel levels in the tanks after a flight. The first such mechanism is unequal flow from each tank to the engine because of (a) greater resistance to the flow of fuel from one tank to the engine than from the other tank to the engine or (b ) a relative vacuum forming in the void over the fuel in a tank (a failure of venting). Problem "a" results from a defect in the airplane's plumbing and problem "b" results from a defect in one of the airplane's tank vent (at least on my CTsw which has no equalizer between tanks). The other issue is transfer of fuel from the fuel tank that is higher than the other tank - this occurs during uncoordinated flight or when parked on a pad that is not level. This transfer can (and does) occur in the absence of a defect in the airplane's plumbing or venting. As noted by Corey, it is a common occurrence when the slip-skid ball is not installed in perfect trim with respect to the wings. In that case, when flying with the ball level, one wing (and its fuel tank) is slightly higher than the other and fuel will transfer from the higher tank to the lower tank. This will happen with properly functioning fuel plumbing and properly functioning tank venting. It simply results from fuel flowing downhill. It would occur in prolonged gliding flight with the engine not running. Link to comment Share on other sites More sharing options...
Fly Boss Posted February 7, 2016 Report Share Posted February 7, 2016 860LS is now at its new home in Virginia. Have completed transition training and additional training to slow the plane down to land. I am using this list all the time for hints and ideas on what is what and why. Today I noticed one tank with 4 gallons and one with 11 gallons while parked in the hanger (dirt). I immediately recognized the slope issue causing fuel to flow downhill. When we returned from our flight and parked the plane, I was tinkering in the plane when all of a sudden the fuel started to level it self out. The glugs we heard as the fuel moved from high to low would have scared any mortal. Add to that the slight movement of the stick as the weight shifted, and people would have been running for cover. After 10 minutes it stopped and the fuel had finished transferring. I shall be bringing a board to the hanger to place under the low wheel from now on. Thanks again for all the wisdom on this list. Link to comment Share on other sites More sharing options...
Tom Baker Posted February 7, 2016 Report Share Posted February 7, 2016 In 8 years of working on CT's I've never heard fuel transferring from one wing to the other, and certainly no glugging from the small lines connecting the tanks. Plus there is no way it should cause the stick to move. If you had the master switch and avionics on when this phenomenon was happening I would bet that the autopilot was accidently engaged. Depending on which autopilot is installed if you hold the dis-connect button on the stick down for 3-5 seconds it will engage the autopilot. I have accidently done this before while performing maintenance. Link to comment Share on other sites More sharing options...
Fly Boss Posted February 8, 2016 Report Share Posted February 8, 2016 In 8 years of working on CT's I've never heard fuel transferring from one wing to the other, and certainly no glugging from the small lines connecting the tanks. Plus there is no way it should cause the stick to move. If you had the master switch and avionics on when this phenomenon was happening I would bet that the autopilot was accidently engaged. Depending on which autopilot is installed if you hold the dis-connect button on the stick down for 3-5 seconds it will engage the autopilot. I have accidently done this before while performing maintenance. You are so correct in this. That is absolutely what happened as I was leaning over that button and the master switch and avionics were both on. Thanks Tom Link to comment Share on other sites More sharing options...
Tom Baker Posted February 8, 2016 Report Share Posted February 8, 2016 Another fuel related self induced gotcha is no fuel draining from the gascolator. If this happens make sure your fuel is turned on. It likely won't drain with the fuel shut off valve in off position. Link to comment Share on other sites More sharing options...
FlyingMonkey Posted February 8, 2016 Report Share Posted February 8, 2016 I flew to Huntsville, AL from the Atlanta area and back yesterday, about 163nm each way. On the way back about 20 minutes in I looked at the sight tubes and saw the right one still full and the left one about 3/4 full. The left tank was draining faster, as is normal for my airplane. I adjusted the rudder trim so the ball was a half ball out to the left (right wing high/left wing low) and flew that way until 20 minutes from home. When I adjusted the trim back out the tanks were pretty close to even, each 2/3 full. It's pretty easy to manage fuel in the CT. Link to comment Share on other sites More sharing options...
Ed Cesnalis Posted February 8, 2016 Report Share Posted February 8, 2016 I adjusted the rudder trim so the ball was a half ball out to the left (right wing high/left wing low) and flew that way until 20 minutes from home... It's pretty easy to manage fuel in the CT. Easy yes but don't you feel like a dork cruising strait with banked wings? Link to comment Share on other sites More sharing options...
Anticept Posted February 8, 2016 Report Share Posted February 8, 2016 Sure. I mean if you're an airplane rolling on the ground between continents, the whole thing seems rather pointless... (strait vs straight ) Link to comment Share on other sites More sharing options...
FlyingMonkey Posted February 8, 2016 Report Share Posted February 8, 2016 Easy yes but don't you feel like a dork cruising strait with banked wings? Meh, nobody's looking. BTW, I have been surprised to see no noticeable speed loss from flying cock-eyed like that. There must be a drag penalty, but I guess in these slippery planes it's very minor. Link to comment Share on other sites More sharing options...
Ed Cesnalis Posted February 8, 2016 Report Share Posted February 8, 2016 I have been surprised to see no noticeable speed loss from flying cock-eyed like that. There must be a drag penalty, but I guess in these slippery planes it's very minor. Perhaps you are removing the slip that is indicated by your centered ball? There would be no penalty for that. I used to be sane but drove myself crazy by constantly visually checking my stubby wing tips for level. Link to comment Share on other sites More sharing options...
FlyingMonkey Posted February 8, 2016 Report Share Posted February 8, 2016 Perhaps you are removing the slip that is indicated by your centered ball? There would be no penalty for that. I used to be sane but drove myself crazy by constantly visually checking my stubby wing tips for level. If that were true I'd be just leveling the wings, and the fuel would flow equally from both tanks (assuming the airplane was built straight). When I put the ball out I can definitely see one tip lower than the other. I too have been known to glance side to side at my wingtips and the horizon more than is healthy. Link to comment Share on other sites More sharing options...
FastEddieB Posted February 8, 2016 Report Share Posted February 8, 2016 Perhaps you are removing the slip that is indicated by your centered ball? There would be no penalty for that. True, but bank+centered ball=turn. Link to comment Share on other sites More sharing options...
Anticept Posted February 9, 2016 Report Share Posted February 9, 2016 True, but bank+centered ball=turn. In typical aircraft with properly functioning avionics! Link to comment Share on other sites More sharing options...
FredG Posted February 9, 2016 Report Share Posted February 9, 2016 Some CTs (mine included) had the EFIS (and, hence, the slip-skid ball) poorly rigged in the panel (perhaps from the factory). So, when the ball was centered, the wings were not level. Before I had his fixed, I would land with a lot more fuel in one tank than the other. After getting the EFIS (and ball) rigged correctly, fuel is nearly equal in my tanks after a long flight. Link to comment Share on other sites More sharing options...
FlyingMonkey Posted February 9, 2016 Report Share Posted February 9, 2016 My D-100 *seems* to be pretty close to correct. The horizon line is not perfectly straight on the ground, but I know my plane is not quite level and one wing tip sits slightly lower than the other. In the air it seems pretty bang on. Link to comment Share on other sites More sharing options...
Ed Cesnalis Posted February 9, 2016 Report Share Posted February 9, 2016 True, but bank+centered ball=turn. Not if the ball needs to be calibrated. Link to comment Share on other sites More sharing options...
FastEddieB Posted February 9, 2016 Report Share Posted February 9, 2016 Not if the ball needs to be calibrated.Granted. I did not pick up on that suggestion from the post in question. I just meant that if a wing is down and the plane is not turning, you are by definition slipping - i.e. too much bank for the rate of turn (in this case no rate of turn). And a properly calibrated ball cannot be in the center in a slip. But, yes, if a ball is out of calibration, that should be addressed before anything else. Link to comment Share on other sites More sharing options...
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