Hi, I am new to this forum and aircraft ownership. I have purchased a 182 and have had a few fuel issues. I am starting to think the solution may be something simple, like not overfilling the fuel tank. I’ve always just had the tanks filled all the way, and at the end of the day so the tanks are full while it sits in the hangar until the next flight. The left wing sits low in the hangar which in turn allows that wing to be filled to the absolute max when I dip the tanks. With this left wing full; in flight; the under wing fuel vent will puff fuel out until the tanks get down to a lower fill level.

I have looked through my POH and cannot find any reference for how full to fuel the plane to have what Cessna considers full tanks. The Cessna 100 manual just says to fill the tanks full. My plane Does not have any reference points/fill tabs in the tank to indicate full.

Also, with the fuel tank transfer in the hangar, I think I’ll start turning the fuel selector to one tank or the other to keep from filling the left tank.

I have adjusted the under wing vent many times. I know Cessna has a very specific location for it, made sure fuel caps vent, installed new poppet valve for wing vent.

Thanks, Ken

Welcome. Unless you land fairly often, fill to the top. Unless more organized than me, leave fuel selector at Both. KISS. Water condensation not as big a problem in Midwest, but drain especially if tanks not topped to overflow.

Barrakudaman wrote:Also, with the fuel tank transfer in the hangar, I think I’ll start turning the fuel selector to one tank or the other to keep from filling the left tank.

I leave mine in the OFF position

I have adjusted the under wing vent many times. I know Cessna has a very specific location for it,

Well yeah. You have a copy of the AMM, right? Otherwise, how do you know how to adjust it?

Look at replacing the vent line with the redesigned McFarlane vent?

https://www.mcfarlaneaviation.com/artic ... -aircraft/

I used to have a slow drip on the ground if the tanks were topped (not in flight, you might have a different issue....). This vent mostly solved the drip on the ground.

The McFarlane vent tube has a curve in it so it goes up to the top skin of the wing. Well, on the 180/185 and early 182, the tube already goes up and attaches to the top skin (by means of an adel clamp). So, not sure what their tube gets you and these specific aircraft.

The plane does have the mcfarline updated under wing fuel vent. The issue is not while the plane is sitting in the hangar; it is in flight. I have looked all over for peoples thoughts on how they fill these planes. I have not found much. some say to fill up to the bottom of the filler neck. It seems you can fill the tank much more than that. I may just completely drain the tanks and add fuel 5 gallons at a time to find out for sure where it should be. I have a pre-made fuel capacity dip stick, but am not certain if it accounts for the extra 5 gallons per wing. These tanks hold 32.5 gallons but 27.5 is what your supposed to consider usable per the POH.

Thanks for your time and responses.

Not sure what your question is. I fill my tanks all the way up using a ladder.

Barrakudaman wrote:The plane does have the mcfarline updated under wing fuel vent. The issue is not while the plane is sitting in the hangar; it is in flight. I have looked all over for peoples thoughts on how they fill these planes. I have not found much. some say to fill up to the bottom of the filler neck. It seems you can fill the tank much more than that. I may just completely drain the tanks and add fuel 5 gallons at a time to find out for sure where it should be. I have a pre-made fuel capacity dip stick, but am not certain if it accounts for the extra 5 gallons per wing. These tanks hold 32.5 gallons but 27.5 is what your supposed to consider usable per the POH.

Thanks for your time and responses.

Here's my opinion on the Cessna. Others may feel different:

Fill it to the brim.

Mind your cross-feed if parked on a slope as you can lose some through the vent. Use the OFF position if you want to prevent cross-feed, but also use a checklist before flight. If you're the kind of guy who jumps in and goes with no checklist or flow, don't use OFF.

We can't do much about the unusable fuel volume, but we can determine how much usable per tank we have. Carefully drain a wing tank using its sump valve into a metal can with a bonding wire until nothing more comes out. That's what you have control over for fuel. Everything else should be considered frosting, and that fuel in the fuel lines could save your butt some day. Start adding fuel back in 3 or 5 gallons at a time, whatever your favorite resolution. Mark your tank dipper stick for each fill level. I like to use a 1/2" wooden dowel about 16" long.

IIRC airplanes are weighed with tanks emptied as I described above, and unusable fuel is factored into empty weight, so don't worry about the 30 lbs for W&B.

Wouldn’t the accurate way to determine usable fuel be to drain it at the gascolator in level flight attitude? The pickup is higher than the tank sump I believe.

My 180 holds less than the stated amount, it’s good to figure out what your plane holds, not what it I supposed to.

StillLearning wrote:My 180 holds less than the stated amount, it’s good to figure out what your plane holds, not what it I supposed to.

So, I take it last time you replaced one of your bladders you slowly filled up your tanks and you couldn't get 32.5 gal in there? (Or 27.5 for you pre'57 guys or 42 for you long-range tank guys) How much fuel did the tank take Stilllearning?

I fill to the max - top of the metal rim on the tanks unless I am concerned about flying a big load or flying where DA is a consideration. You actually have 58 usable (29 per side) for level flight. I am not sure why we Cessna designed the fuel system with 7 pounds of dead weight in unusable fuel. The impact pressure on the fuel vent causes my left tank to drain faster than the right side but it always seem to equilibrate as I get past about 1/2 tanks. I keep the selector on both and try to land with 10 gallons reserve. I suppose I could adjust the selector L/R - but I really love just keeping it simple as contact flying mentioned - just leave it on both. It is a nice feature of Cessnas. I wish I had more usable fuel but usually my range is limited by my bladder.



Josh

StillLearning wrote:Wouldn’t the accurate way to determine usable fuel be to drain it at the gascolator in level flight attitude? The pickup is higher than the tank sump I believe.

My 180 holds less than the stated amount, it’s good to figure out what your plane holds, not what it I supposed to.

This is how I do my weight and balances and tank calibrations. This is more accurate then just adding the unuseable IMO. Then fill right to the brim amd see how much it holds.

Ok, it seems most of you fill to the brim (as much fuel as possible). I will continue filling the tanks with as much fuel as possible.

I did not want to continue chasing this underwing vent issue if the solution was just filling the tank less/correctly.

Thanks, Ken

StillLearning wrote: Wouldn’t the accurate way to determine usable fuel be to drain it at the gascolator in level flight attitude? The pickup is higher than the tank sump I believe.......

I like to drain all the gas out when doing a weight & balance.
Draining at the gascolator after levelling is how I do it.

However, I believe that "usable fuel" is defined as that which is available in all attitudes--
not just in level flight.

Barrakudaman wrote:I did not want to continue chasing this underwing vent issue if the solution was just filling the tank less/correctly.

Thanks, Ken

What is there to chase? Adjust the vent according to the dimensions shown in the AMM and call it a day. You are an A&P, right?

Ken: I have a 62 182. When full the vent (only have one, under left wing) would sometimes spray out fuel while in flight and if tanks were full. My wizard mechanic adjusted it verycarefully, and much spray decreased to virtually zero.

Our planes have severe crossfeed also, and right tank will siphon fuel into left tank during flight when starting full. The left wing then gets heavier than right. Its a design issue.

If you park on a slope with left wing low fuel will sometimes drop out the vent, as the right tank can then drain into the left.

Sometimes with full tanks I switch to left only after stable after takeoff. Run that awhile, then switch to both. I takeoff and land on both.

hope this helps

Sean

Thanks Sean,


This underwing vent does not seem to be just a simple thing to adjust. I have had my AMP adjust it four times with no luck, including the new poppet valve, new seals for the vented caps, and a look through to make sure both tanks are venting from side to side.

I have one vent under the left wing.

Ken

hotrod180 wrote:

StillLearning wrote: Wouldn’t the accurate way to determine usable fuel be to drain it at the gascolator in level flight attitude? The pickup is higher than the tank sump I believe.......

I like to drain all the gas out when doing a weight & balance.
Draining at the gascolator after levelling is how I do it.

However, I believe that "usable fuel" is defined as that which is available in all attitudes--
not just in level flight.

That is correct, so the accurate way to determine the official “unusable” fuel is to put the aircraft at the extreme pitch attitudes that it could see in an aggressive climb out, then drain the tanks. Usually in level flight you can use a significant portion of the unusable fuel. One example, unusable fuel in an RV4 is 1.5 gallons per tank, however in level flight (or a slight side slip) you can get nearly every drop of gas out of one tank. At low cruise, that equals another 15 minutes of flight in that plane. That technique is not so appropriate for my 185 with it's crossfeed, since in “both” (position for takeoff and landing) the fuel will flow back into the previously empty tank.

Also, not sue about earlier 180/182/185s , but later ones need to be in “left” or “right” to prevent cross feeding. Fuel can still flow tank to tank in “off”

fredy wrote:.......not sure about earlier 180/182/185s , but latter ones need to be in “left” or “right” to prevent cross feeding. Fuel can still flow tank to tank in “off”

My 53 C180 does not cross-feed with the fuel selector in the off position,
but it does on both.

I agree, the vent adjustment is very sensitive. Another cessna outfit (cessna pilots association??) used to have measurements for placing the vent exactly in position behind the strut. I am very, very lucky in that the person working on my plane is really good.

Sean