Running dry?

Recently, Roy Smith posted:

"Neil Gould" wrote:
At most all you've learned is what the fuel capacity of your tanks
are, and that could be more accurately established while on the
ground, FWIW. In fact, the POH should suffice, unless you intend to
violate FARs as a regular practice.

What FAR says you may not run a tank dry?

The FARs address minimum fuel levels when you arrive at your destination.
If you have less than the required amount when you land, you are in
violation. If you are managing your fuel consumption adequately, there is
no need to run your tank dry.

Given that "how much fuel you really have in your tanks"
is only one factor in how long you can continue to fly, and that
those other factors aren't addressed by running your tanks dry, what
*is* the point in doing so?

Assume you are flying something with two tanks and no "both" position
on the fuel selector. You're 30 minutes from your destination, which
would you rather have: an estimated 30 minutes of fuel left in each
tank, or have one tank dry and an estimated hour's worth in the other?

I regularly fly something with two tanks and no "both" position (PA28),
and my preference is to arrive at my destination with more than 30 minutes
worth of fuel, period. I see no point in pushing those limits any more
than seeing how much over gross I can fly. IMO, such points are just
useless information. YMMV.

Neil

On Sun, 21 Aug 2005 16:13:30 GMT, "Neil Gould"
wrote:

Recently, Ron Rosenfeld posted:

On Thu, 18 Aug 2005 15:42:31 GMT, "Jay Honeck"
wrote:

IMHO, proper fuel management means never even coming *close* to
running a tank dry, let alone doing it intentionally.

And how do you know how much fuel you really have in your tanks?

At most all you've learned is what the fuel capacity of your tanks are,
and that could be more accurately established while on the ground, FWIW.

Capacity on the ground is not worth much. I'm more interested in useful
fuel during flight at cruise attitude.

In fact, the POH should suffice,

If I follow your advice, I would assume 26 gallons per side. That would be
pretty stupid since I can't get 26 gallons into a tank after running it
dry!

unless you intend to violate FARs as a
regular practice.

How does knowing your real fuel capacity lead to FAR violations?

I would think that NOT knowing your real fuel capacity will be more likely
to lead not only to FAR violations, but also be more likely to landing
short of your destination.

Given that "how much fuel you really have in your tanks"
is only one factor in how long you can continue to fly, and that those
other factors aren't addressed by running your tanks dry, what *is* the
point in doing so?

Well, I like to know how much fuel I have in my tanks. That gives me
information such as, "how long can I hold to wait for weather improvement
before diverting to my alternate" (and still have comfortable reserves when
I land there). And that scenario does occur in this part of the world.

It is certainly possible to adopt practices that would make knowledge of
your fuel capacity relatively unimportant. And if you choose to fly that
way, that's your decision. But I'd like to be able to get more utility out
of my airplane, and knowing its limitations allows me to operate at a safe
margin within those limitations.


Ron (EPM) (N5843Q, Mooney M20E) (CP, ASEL, ASES, IA)

Ron Rosenfeld wrote:

On Thu, 18 Aug 2005 15:42:31 GMT, "Jay Honeck"
wrote:


IMHO, proper fuel management means never even coming *close* to running a
tank dry, let alone doing it intentionally.

And how do you know how much fuel you really have in your tanks?

It seems simpler, and safer, to figure this out by running the tanks dry,
at least once, than to trust the manufacturer's numbers.

Wouldn't it be safer (maybe not simpler) to just drain the tank on the
ground to find out?


In my case, I
have about four gallons less than the published numbers which is 1/2 hour
at economy cruise which is VFR reserves.

That's very important to know, but I still think that find out from the
safety of the hangar would be the best choice.

I find it very interesting that the "run the tanks dry occasionally"
group uses the argument that it is is about safety: knowing exactly how
much fuel your tank(s) hold. If they are truly interested in the
safety, it would seem to me that they would perform that operation on
the ground with a pony pump, some rubber hose, and a couple of clean 50
gallon drums (or a lot of clean buckets/gas cans).

The only two reasons I can see for intentionally running a tank dry are
to accurately determine your fuel flow (which doesn't really help you
since it's after the fact) or to extend your range to the absolute
maximum, which comes back to whether or not that's a good idea.
Personally, I think it's foolish since at worst, refueling adds an hour
to your trip and the break to stretch your legs helps prevent fatigue on
really long trips.


-m
--
## Mark T. Dame
## VP, Product Development
## MFM Software, Inc. (http://www.mfm.com/)
"OK, who stopped the payment on my reality check?"

Well, after reading probably 100 posts in this thread over the past couple
of days, I've got a question to put to you all. What is the chance that
you run a tank dry and the switch to the other tank, only to discover that
you had a collision with a tree on takeoff and the other tank (along with
half the wing which contained it) was torn right off the airplane, and you
never noticed. Then you'd be in deep doo-doo, right?

What is this lunatic talking about, you ask? I'm talking about...

http://www.thesun.co.uk/article/0,,2-2005380500,00.html

Well, after reading probably 100 posts in this thread over the past couple
of days, I've got a question to put to you all. What is the chance that
you run a tank dry and the switch to the other tank, only to discover that
you had a collision with a tree on takeoff and the other tank (along with
half the wing which contained it) was torn right off the airplane, and you
never noticed. Then you'd be in deep doo-doo, right?

What is this lunatic talking about, you ask? I'm talking about...

http://www.thesun.co.uk/article/0,,2-2005380500,00.html

Yep. Just when you think you've seen EVERYTHING possible, a guy like this
takes to the air in a seemingly non-airworthy plane, and flies innocently
into infamy.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

Many of you, it seems never read Deakin's article, or have given much
thought to the procedure. My normal fuel management, when we'd tow
banners, was takeoff on the left tank (the "main" because it has
pickups in the front and back of the tank) and fly for 30 minutes.
Depending on the day and the size of the banner, that would leave :45
to 2:30 hours remaining (fuel burn ranged from 5.2 gph to 9.5 gph.
Switch then to the right tank, and run dry.

Worst case scenario, and I have contaminated fuel in the right tank, I
still have enough in the main to get home on. After running the right
tank dry, I'd know EXACTLY how much longer I could stay on station, and
still land with my required reserve. Normally, I could predict within
5 minutes when the tank would run out, and I'd climb to a safe altitude
in preparation (usually 600' AGL) the most altitude I ever lost while
the engine restarted was 100' on a silky smooth day when that tank ran
TOTALY dry at once, normally it would sputter and cough a few times
first.

In addition to now knowing how much endurence I had, this also meant
that all my fuel was in one tank, and as others have said, if I was to
land with :30 minutes of fuel at 5.5/hr, I'd much rather have all 2.8
gallons in one tank, rather than 1.4 in each! In practice, we never
landed with less than 45 minutes though; we'd want to have enough to
get to our field, attempt a drop, go around with a fouled banner, and
then proceed to the nearest paved runway, land, and fly back to base.

A friend of mine very nearly put one in short of the runway once
because someone else wasn't familiar with the fuel burn, and fuel
capacity. He routinely would get a safe 5 hour endurance out of his
plane, with reserve. Someone else flew it on his day off, and landed
with both tanks on "E" This means very little in a Super Cub, as the
last mark on the gauge reads "3pt attitude- 1/4 to E".

The next day, we didn't have fuel at our strip, and had to refuel at a
nearby airport (4 miles distant). He took off on the last selected
tank (figuring that it was the one landed on, it would be the fullest)
it ran dry on him 1 mile from the airport. Swiching tanks, he was able
to get a restart, and taxi in to refuel. 17.4 gallons was pumped into
the dry tank, and 17.2 into the other. The other pilot later claimed
he "knew you flew it for 5 hours, so I landed after 4" He thought he
had at LEAST a 1:30 hour reserve when he landed, in reality, it was
about 4 minutes.

They were both very lucky; had the other pilot run a tank dry (damn
near did anyway) he would have known his endurance estimate was way
off, and he'd have to land sooner than anticipated. Of course, the
prudent thing to do would have been to drain 5 gallons from another
airplane and pour it into my friend's plane, to be sure he could make
it, but we both assumed that our coworker wouldn't land with less than
5 minutes of fuel in the tanks.

Food for thought,
Mike

Mark,

refueling adds an hour
to your trip and the break to stretch your legs helps prevent fatigue on
really long trips.


IF there is an airfield with fuel along the route. Which often isn't the
case.

Also, consider an airplane with 4 or even 6 fuel tanks, not at all
uncommon. Leaving, say, 5 gallons sloshing around in each robs you of 25
gallons of fuel - which is at least 1.5 hours flying time. That is quite a
lot. In fact, it could be considered a really good reserve. Except for
that, you'd want it all in one tank.

--
Thomas Borchert (EDDH)

Recently, Thomas Borchert posted:

Mark,

refueling adds an hour
to your trip and the break to stretch your legs helps prevent
fatigue on really long trips.


IF there is an airfield with fuel along the route. Which often isn't
the case.

It's pretty rare not to find fuel within range in the US if you're east of
the Rockies or west of the Sierras. So, I'd think it's "often" the case if
you only fly in the stretch between the Rockies and the Sierras. ;-P

Neil

Thomas Borchert wrote:

refueling adds an hour
to your trip and the break to stretch your legs helps prevent fatigue on
really long trips.

IF there is an airfield with fuel along the route. Which often isn't the
case.

In my flying experience (admittedly east of the Mississippi is different
than flying out west) it's rare to not be able to reach an airport in
less than 15 minutes from wherever you are in the sky. But, regardless,
I fly a Cherokee Six for anything longer than two hours, which gives me,
conservatively, over five and half hours of gas. Since I don't fly
longer than four hours at a stretch (see above), I always have at least
1.5 hours reserve planned in. Sure that's more conservative than a lot
of people, but it's just not worth it to me to stretch it. An hour out
of my way to refuel is not that big of a deal. Trying to stretch my
range to save an hour, in my mind doesn't get me anything.


Also, consider an airplane with 4 or even 6 fuel tanks, not at all
uncommon. Leaving, say, 5 gallons sloshing around in each robs you of 25
gallons of fuel - which is at least 1.5 hours flying time. That is quite a
lot. In fact, it could be considered a really good reserve. Except for
that, you'd want it all in one tank.

No, I wouldn't. I like having options. The way I fly, if I go for my
max endurance (mine, not the plane's) of four hours, I land with one
tank with 45-60 minutes of fuel and three others with 10-20 minutes
each. Since I'm landing with at least 45 minutes of fuel in the last
tank, the 30-45 minutes in the other three tanks is unnecessary. If I
had a problem with that tank, I have three others to choose from. If
all of my fuel is in one tank, I have no options. Sure, I would have to
really be on my toes in case the tank I switched to runs dry, but that's
better than not even having that option.

Basically, I fly with the attitude that no matter what happens, I will
have another option. In practice that's virtually impossible to do
(what option do you have if a Canadian goose flies through your
windscreen?) but somethings are easy. Fuel is one of the easy ones.

No, I won't go so far as saying that those that run tanks dry as part of
their fuel management system are dumb, but I will say that I feel that
they are taking an unnecessary risk. That's not a personal attack, just
my opinion of the practice. There are a lot of things I do that other
people consider taking unnecessary risks (and therefore a foolish thing
to do), like riding a motorcycle without a helmet. But, it's my choice
to do so.


-m
--
## Mark T. Dame
## VP, Product Development
## MFM Software, Inc. (http://www.mfm.com/)
"Don't be a flower snack!"
-- My son, "The Bean"

On 2005-08-22, Mark T. Dame wrote:
Wouldn't it be safer (maybe not simpler) to just drain the tank on the
ground to find out?

Maybe not unless you are geared up with the right equipment (a proper
fuel tank that can hold however many gallons the fuel tank can) and the
right firefighting equipment.

--
Dylan Smith, Castletown, Isle of Man
Flying: http://www.dylansmith.net
Frontier Elite Universe: http://www.alioth.net
"Maintain thine airspeed, lest the ground come up and smite thee"