Uneven fuel tanks C152

[modelman]

Have noticed that the left tank always seem to empty faster that the right one ( and on C150 I've flown)
Flew to IOW today (80mins) and the left tank was a lot lower than right.Although I had enough fuel for the return,I added some more to left tank to even things up a bit-was I worrying about nothing?

MM

[flybymike]

As they say. "You can never have too much fuel on board unless you are on fire"
Fuel imbalance in the 150 and 152 is a well known and irritating phenomenon. usually caused by flying imperceptibly out of balance ( check ground adjustable trim tabs,) and or parking on uneven ground, sideslipping, unco-ordinated turns etc. However with all fuel routing via a single outlet should be no ultimate problem No harm in keeping lateral balance correct by topping up a low wing though.

[RatherBeFlying]

Fill lower wing first as there is a connection between wing tanks.

If you don't, someday you will take the cap off the lower tank and have fuel flowing out all over the wing.

Don't be smoking around airplanes now:ouch:

[sternone]

I had the same thing in a C152 with long range tanks, the left one was almost completely empty and the right one was half full... wich i don't understand since both thanks communicate to eachother ? on a real slow flow i assume....

[dmjw01]

was I worrying about nothing?
In short, yes. If the total fuel on board was adequate then you'd have been fine. It is very common on high-wing Cessnas for one tank to initially drain faster than the other, but there does come a point when the other one starts catching up again.

[mccourtm]

On the subject of uneven fuel tanks, what is the procedure for switching tanks on a 172sp. I couldn't find any reference in the POH. Should you use the fuel pump or not? If you use the fuel pump do you risk flooding the engine since the fuel is gravity fed?

Rgds.

[SkyHawk-N]

It's a known/excepted quirk of high wing Cessnas and is nothing to worry about, the engine will not stop if one tank empties before the other (as long as you have selected 'BOTH' on the fuel selector!!!!). I have an article that was given to me about this if anyone is interested. PM me and I'll see if I can find it.

Uneven fuel feeding can be worsened by the tank vent (under the port wing on 172s) being incorrectly positioned. If the vent opening is not hiding behind the strut the tank can become slightly presurized and uneven feeding can be more noticeable.

[sternone]

(as long as you have selected 'BOTH' on the fuel selector!!!!)

On the Cessna 152 and 150 there is no BOTH position, just on and off...

[Speedbird48]

On all single engine Cessnas there is a critical adjustment to the fuel vent pipe below the wing. It is shown in the Maintenance manual and the length of the pipe protruding below the wing is measured in very small numbers.

That combined with the vented cap on the other side is what make it flow evenly.

Another cure, not in the manual, is to get another vented cap and put it on the opposite tank so that you have 2 vented caps and one vent tube.

Speedbird 48.

[Shunter]

Speedbird - would that apply to my 177? I've noticed it has a preference to pull from the left tank despite flow test showing they were flowing identically in terms of litres/hour.

I was aware of the balance thing, so deliberately went out and flew half an hour of right hand orbits with both selected. Still drained the left tank as a preference. The 177 has the crossover vents (ie. left vent on right side, right vent on left side).

As has been mentioned, when one empties, the engine doesn't suddenly stop, but it would be nice if they flowed evenly all the time. I tend to alternate tanks to make sure the weight stays even.

edit: appalling grammar

[SkyHawk-N]

Shunter, in section 2.3 of your POH it states that "unequal fuel flow from each tank may occur if the wings are not maintained exactly level". With the 177 they recommend switching tanks regularly, this is not recommended with the 172.

Make sure you leave the fuel selector on RIGHT when securing your aircraft (also in the POH) and when refuelling.

[Speedbird48]

Shunter,

The vent system on the 177 is quite different from the 172/182 series in that it doesn't have a vent pipe sticking out of the bottom of the wing, The manual does say to regularly switch tanks to achieve balance.

However, the Cessna Pilots Association, http//www.cessna.org has a lot of information that may help you. As I don't have a 177 I have not shown a lot of interest but, I do remember some posts on their site about you issue.

If you have trouble getting on please PM me. I may take a couple of days to get back to you, but I will do it.

Speedbird48

[AARON773]

I have this very problem in my 150 but nothing to worry about.

[S-Works]

Just about the most talked about thing in Cessna flying. My 152 used to be very bad for it if you flew with the slightest amount of yaw which was pretty much all the time when you only had 1 POB. With a passenger it would fly level and the draw was much more even. After a long flight I have landed with the RH tank totally empty.

My 172 does the same thing to a much lesser degree. Often after a lot of local flying there will be a 8 or 9l difference when I refill the tanks. On a long level cruise in the airways the difference is a lot less around 1/2l.

[JammedStab]

It can mask a real problem though. Perhaps be concerned if one tank stays completely full....

"N11512, a Cessna 150L aircraft was conducting a day VFR flight from Earlton/Timiskaming Regional, ON (CYXR) to Marathon ON, (CYSP). During the flight, the pilot observed that only the left fuel tank was feeding the engine. The fuel gauges indicated that the left fuel tank quantity was decreasing, while the right fuel tank remained full. The aircraft fuel selector has two positions: ON or OFF. The pilot flew the aircraft with the left wing low for a period, in an attempt to obtain fuel from the right tank. As the aircraft was approaching CYSP, an engine power loss occurred.

At approximately 1430 EDT, the pilot force landed the aircraft into a remote area approximately 9 nm east of CYSP. RCAF search and rescue (SAR) aircraft and personnel were dispatched from Trenton. The aircraft was located having sustained substantial damage; the pilot received minor injuries."