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WmInce

Fuel Quantity Dipstick

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Regarding the fuel quantity dipstick, one side is labeled "right" and the other side is labeled "left."

So my question is . . . when reading the side that's labeled left, does that correspond to the port side wing tank or the starboard side wing tank?

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Point the larger top section (unscrew fuel cap insert) of the stick to the 'outside' of the wing, or the wing tip.... If standing at the leading edge, than you are reading the correct side.  (This is in your POH)

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.... If standing at the leading edge, than you are reading the correct side.

 

So let me get this straight. If I am standing in front of the port side wing, I should be using the side of the dipstick that is stamped "RIGHT?"

 

(This is in your POH)

 

Where in the POH? I have not found it in the CTSW POH. Page number?

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Remember right is always right and same with the left no matter where you stand and face the plane. As mentioned above the large end points to the outside of the wing. That then corresponds to the correct wing. The "R" on the stick will be in the right wing tank.

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My dipstick was not anywhere near accurate.  Right was more accurate than left, but both were off.  I drained the tanks and filled them at 5, 10, and 15 gallon increments, and then make my own scratch marks in the stick so they are now accurate.  I highly recommend calibrating your stick in a similar way before trusting what it tells you to make long range fuel calculations.

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My dipstick was not anywhere near accurate.  Right was more accurate than left, but both were off.  I drained the tanks and filled them at 5, 10, and 15 gallon increments, and then make my own scratch marks in the stick so they are now accurate.  I highly recommend calibrating your stick in a similar way before trusting what it tells you to make long range fuel calculations.

Thanks Andy. I may do that. I am very suspect in the accuracy of my dipstick markings also.

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Thanks Andy. I may do that. I am very suspect in the accuracy of my dipstick markings also.

 

I think they are good enough to say the tank is half full or almost empty, but in my case it was not any more accurate than that and I wanted a bit more resolution.  My sight tubes are more accurate than that, I've got them calibrated accurately within a half gallon.  But when there is more than ten gallons in a tank the tubes are just full and you don't know how much more than ten gallons you have in that tank.

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The dip stick works perfectly fine (the Flight Design dip or any rigid flat piece of aluminum will do).   A good rule is to never fly with less than 1/3rd of the stick wet in the lowest qty wing.    The actual number of gallons do not matter for three reasons.  1. the stick cannot be trusted to any real degree of accuracy other than the 'wet' sight test.  2. there are no fuel qty sensors in the wings   3. the sight tubes cant be used to determine a gallon amount.

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I disagree, gallon amounts *do* matter.  If I burn five gallons an hour and I'm planning a three hour flight, what does the fuel being halfway up the stick in each tank tell me about whether I can make the flight with adequate reserves?  What if, like in my airplane, the indicated fuel halfway up the stick has no relation to having half full tanks?  How can you adequately flight plan?

 

Even if the CT had fuel gauges, you are not allowed to rely on them according to the FAA.  By FAA standards, aircraft fuel gauges only have to be accurate in one condition -- when the tanks are empty.  In no other condition can you rely on mechanical fuel gauges.

 

And you are mistaken about not being able to determine a gallon amount from the sight tubes.  I have carefully calibrated and marked mine on both sides, and they are very accurate.  For example, on my last long trip I took off with 30 gallons of fuel and flew 250nm each way, carefully watching my fuel state on the way back using only the sight tubes.  When I landed I estimated I had 8 gallons remaining.  I drained the tanks to check my calculations, and drained 8.2 gallons from the airplane.  I'll put that accuracy against 90% of mechanical gauges.

 

If you can't determine a fuel state from the sight tubes, what are they for? 

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The plane burns 4 to 5 gph.  And has a 34 gallon capacity.  The CTLSi has a bit more with the header tank.  If you see 1/3rd on the stick lowest between the wings thats about 10 plus gallons left or about 2 hours to empty at the worst burn rate.  Which is 4x the required VFR fuel mins at takeoff. 

 

The site tubes do not tell you gallons, they tell you fuel levels...and even that is not very accurate given sloshing, roll etc.  And the fact they get dark over time if you use leaded fuel.

 

Anyone planning to fly 250nm is flying a long cross country.  Any long cross country flight should begin with a fueling stop at the pumps (or fueling from your hangar supply) and filling the tanks.  

 

The point I am trying to make is - the CT fuel management should be done conservatively without expecting to know the exact number of gallons in the plane.  Plan fuel and flying around an over-kill of fuel since the margin of error can be much larger than with planes that have wing fuel sensors and a way to tell how much fuel is actually in the wings at any given time (as is true with the Cirrus).

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I must have gotten lucky with my CTLS. The stick seems accurate based on adding a known quantity after draining the tanks and it agrees with the Dynon fuel remaining after a flight.

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This may be more an operator error. If the stick is held at a slant or sits on a little ridge inside it may be off. When I do a wing inspection I replace the sight tubes. Then I put 5 gal. of fuel in each wing and mark it on the sight tube. Then I dip the stick. They all come out extremely close and more than accurate for an operator checking fuel quantity. If you are splitting hairs between .25 to .5 gals. then that's the problem. To be perfectly on mark each time you would have to find a level parking spot, level the plane and make sure you dipped the tank the same each time.

 

This is only a guide and not 100% perfect fuel level check. You either have enough fuel for your mission or you don't. If you're splitting hairs on a fuel mission you are already doing something wrong in your planning.

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I always put the stick against the back of the filler so that it is as close to consistent as I can get.

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I always put the stick against the back of the filler so that it is as close to consistent as I can get.

 

As do I.  There is a little "shelf" in the bottom of the tank, maybe 1/4" high.  I position the stick so it sits against the back edge of the shelf and the rear of the filler hole, which makes it almost perfectly upright.  That gives me repeatable results.

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