Doug G. Posted November 25, 2014 Report Share Posted November 25, 2014 For some reason I never thought this way before. I know that my CTLS will hold 34 gallons of fuel with 32 useable. I have always taken this into account when filling, but one of those "bang your head on the wall" moments happened to me today. It should have been obvious to me that it is the last two gallons that are unusable. So, if I stick the tanks and I come up with 10 gal. (Which I would figure to be about one hour with a one hour reserve.) It is actually 8 gal. (Which I would see as half an hour with a one hour reserve.) Fortunately I haven't ever flown that close to the limits. Just posting this for anyone else that has a brain like mine. Link to comment Share on other sites More sharing options...
FastEddieB Posted November 25, 2014 Report Share Posted November 25, 2014 I would expect the sticks to be calibrated as usable fuel in the tank. I don't ever recall seeing otherwise. Link to comment Share on other sites More sharing options...
Jim Meade Posted November 25, 2014 Report Share Posted November 25, 2014 The CTSW stick is calibrated to 17 gallons, which is the POH capacity of the tank, although usable fuel is stated as 16.5 per side. Link to comment Share on other sites More sharing options...
Anticept Posted November 26, 2014 Report Share Posted November 26, 2014 Unusable fuel is also what is in the fuel lines. During W&B recalculations, us mechanics have to consider that arm and moment too. Link to comment Share on other sites More sharing options...
Anticept Posted November 26, 2014 Report Share Posted November 26, 2014 Lines with 2 oz of fuel? The CTLSi also has a header tank which has 1.6 gallons of which 1.1 is usable. Just don't go below 5 gallons and you will be swell. Doesn't matter how much or little it is. It's standard industry practice, and It is required to be considered for W&B calculations. Generally we don't need to worry about it though, since we either calculate full tanks, or empty with unusable on board. It's usually not a big deal though unless we weigh with a dry fuel system, then it needs to be added in. Link to comment Share on other sites More sharing options...
Doug G. Posted November 26, 2014 Author Report Share Posted November 26, 2014 I will have to look next time to see if my stick reads to 16 or 17 gal. I measure with the stick against the back of the filler, and although I have not done the incremental fill to mark the sight tubes, I do know that when I add fuel it makes sense, and my Dynon is very accurate in fuel burn and fuel remaining. Link to comment Share on other sites More sharing options...
WmInce Posted November 26, 2014 Report Share Posted November 26, 2014 Unusable fuel is "trapped fuel," which cannot be accessed for consumption by the power plant. Link to comment Share on other sites More sharing options...
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