Has anyone heard of a problem in earlier (1974) C182s where one fuel tank will draw down 3/4
before drawing from other tank when fuel selector in "Both" position? If so, any articles online?

Richard

"Richard Ross" > wrote in message
...
> Has anyone heard of a problem in earlier (1974) C182s where one fuel tank
> will draw down 3/4
> before drawing from other tank when fuel selector in "Both" position? If
> so, any articles online?


Yes. Cessna Pilots Association knows all about this. They have articles
online, but you have to be a member of CPA to view them. I think they're a
great organization. AVweb may have articles on this subject, too.

This is a common occurrence with older 182s. I understand that it is
due to the design of the venting system - that was supposedly corrected
in later models. I have read an article on the sugject, but don't
remember where I saw it.

David Johnson

Same problem on many Cessna high-wing singles. They have tried to place
the little, forward-facing vent just behind the strut, to minimize the
slight static pressure that develops in flight, but you'll still have a
faster draw from one side. In my experience, newer models are no better.
There are literally dozens of articles on the subject, and as many
proposals for fixes. Some of these are probably good, and you should do
some internet research if this is bothering you. My own fix is simply to
switch to right tank only once I'm in cruise, and manage the disparity
from there. Back to both, of course, in the pre-land checklist.

GF

Check the fuel tank cap seals. On that airplane they have
O-rings that are supposed to be checked yearly (there's an AD on it) to
prevent leaks, both water in and air out. The O-rings get old, hard,
and cracked. A leak on the right side will create a slightly lower
pressure that on the left, and the left tank will drain faster. A big
enough leak will suck a lot of fuel out of the tank and collapse the
bladder.
Cessna sells a kit to replace those caps with the style we see
on the 172, minimizing the problem.
We run three Cessna 172s, an R182 and two Citabrias, all
with the same venting system, and as long as we keep the seals tight
the fuel drains evenly. As soon as a cap develops a leak the uneven
drainage shows up.
The vent under the left wing bothers some people, as they
think the left tank gets more pressure than the right, but if things
are otherwise sealed the pressures are equal in both tanks (Boyle's
Law) and uneven drainage is more likely due to restrictions in the fuel
lines. When the tanks are full or near full there's some fuel movement
between tanks (left to right) through the vent interconnect, but
certainly not 3/4 of a tank's worth.

The fuel cap AD:
http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgAD.nsf/0/6B7E237247839196862569B9004D108C?OpenDocument

AOPA's take on the 182 uneven fuel feeding:
http://www.cessna.org/store/buyers_guides/182/182_guide_excerpts.html
AN exceprt from that excellent article: "This condition can be
minimized somewhat by adjusting the position of the fuel vent behind
the lift strut on the left wing, making sure that fuel caps seal
tightly so that the "head pressure" in one tank is not altered by a
leaking cap..."

Dan

On Wed, 26 Apr 2006 19:34:09 -0600, Jon Woellhaf wrote:

> They have articles
> online, but you have to be a member of CPA to view them.

I'm a [relatively new] CPA member. What's the best way to locate these
articles?

- Andrew

Richard,

What you are seeing is normal.

You will see many so called "fixes", but none of them address the fact that
most Cessnas have done this forever, even brand new, and will continue to. I
have ferried many new Cessnas from Wichita and they all did the same thing,
including a gorgeous A185E I bought new for myself.

If it bothers you or you get a heavy wing in flight just switch to the
fuller tank for a while. I've never heard of a Cessna running out of fuel
when "both" is selected and there was usable fuel in one wing .

That's not to say that you might not actually have a problem, like a
blockage in a vent line or something. I'm just saying that if you have it
checked out and they find nothing, don't worry.

Best,
Karl
ATP, CFI, ETC.

"Curator" N185KG


"Richard Ross" > wrote in message
...
> Has anyone heard of a problem in earlier (1974) C182s where one fuel tank
> will draw down 3/4
> before drawing from other tank when fuel selector in "Both" position? If
> so, any articles online?
>
> Richard
>

"Andrew Gideon" > wrote in message
...
> On Wed, 26 Apr 2006 19:34:09 -0600, Jon Woellhaf wrote:
>
>> They have articles
>> online, but you have to be a member of CPA to view them.
>
> I'm a [relatively new] CPA member. What's the best way to locate these
> articles?
>
> - Andrew

Log in and take the TechNotes link. Then take the TechNotes link. See
TechNote 003.

That problem is present on a 1986 'R' model that I fly, the FBO guy at a
nearby airport always comments on it when I stop by for cheap(er) fuel.


--
Hello, my name is Mike, and I am an airplane addict...

In article >,
"Michael Ware" > wrote:

> That problem is present on a 1986 'R' model that I fly, the FBO guy at a
> nearby airport always comments on it when I stop by for cheap(er) fuel.

The 182R and 182S that I fly have the same habit.

On Thu, 27 Apr 2006 11:51:46 -0600, Jon Woellhaf wrote:

> Log in and take the TechNotes link. Then take the TechNotes link. See
> TechNote 003.

Ah, the tech notes. Thanks.

That is a site that really needs a search; lots of information but not all
easily found.

- Andrew

On Thu, 27 Apr 2006 08:57:11 -0700, karl gruber wrote:

> f it bothers you or you get a heavy wing in flight just switch to the
> fuller tank for a while.

In either an R182 (1979) or 182Q (1980) (I cannot recall in which I did
this test), switching to the most full tank doesn't have the effect one
hopes. It still seems to draw more from the "wrong" tank (although in fact
it's probably drawing from the selected tank with fuel moving through the
interconnect to replace the drawn fuel).

The CPA tech note only refers to pre-1979 models. This may be of great
value to the OP and his 1974 182, but many of us are apparently
experiencing at least similar problems in models of 1979 and beyond.

- Andrew

"Andrew Gideon" > wrote in message
...
> On Thu, 27 Apr 2006 08:57:11 -0700, karl gruber wrote:
>
>> f it bothers you or you get a heavy wing in flight just switch to the
>> fuller tank for a while.
>
> In either an R182 (1979) or 182Q (1980) (I cannot recall in which I did
> this test), switching to the most full tank doesn't have the effect one
> hopes. It still seems to draw more from the "wrong" tank (although in fact
> it's probably drawing from the selected tank with fuel moving through the
> interconnect to replace the drawn fuel).
>
> The CPA tech note only refers to pre-1979 models. This may be of great
> value to the OP and his 1974 182, but many of us are apparently
> experiencing at least similar problems in models of 1979 and beyond.
>
> - Andrew
>

They all do it. If your Cessna is draining equally from both tanks,
something is wrong!!