How safe is it, really?

"Stefan" wrote in message
...
Happy Dog wrote:

ALWAYS refuel after every flight, so that we always have full tanks.

I don't know why more pilots don't do this.

I don't know what you are flying, but with the planes I fly, full tanks
aren't an option unless I want to fly alone.

It should be obvious that I wasn't suggesting that anyone overload their
aircraft.

m

Happy Dog wrote:

ALWAYS refuel after every flight, so that we always have full tanks.

It should be obvious that I wasn't suggesting that anyone overload their
aircraft.

If you refuel after each flight to *full* tanks, as suggested, chances
are you will be overload on the next flight unless you drain some fuel.
Maybe not if you're the only pilot who flyes the plane and you have a
certain loading pattern, but certainly in a club (or FBO) environment.

In our club, we *forbid* people to fill the tanks after a flight to more
than two thirds.

(I know it wasn't you who suggested it, but you confirmed the suggestion.)

Stefan

If you refuel after each flight to *full* tanks, as suggested, chances are
you will be overload on the next flight unless you drain some fuel. Maybe
not if you're the only pilot who flyes the plane and you have a certain
loading pattern, but certainly in a club (or FBO) environment.

Your club needs to get a Pathfinder or Dakota.

Full tanks (84 gallons), four 200 pound guys, plus luggage -- no problemo!

;-)
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

"Happy Dog" wrote:
ALWAYS refuel after every flight, so that we always have full
tanks.

I don't know why more pilots don't do this.

I don't know what you are flying, but with the planes I fly, full
tanks aren't an option unless I want to fly alone.

It should be obvious that I wasn't suggesting that anyone overload
their aircraft.

No, but you were wondering why more pilots don't "ALWAYS refuel after
every flight, so that [they] always have full tanks," which is a silly
practice unless one ALWAYS knows the next flight will require full
tanks. At my old club, members were asked NOT to fill the tanks after
using the airplanes, so that the next pilot could add fuel appropriate
to his flight.
--
Dan
C172RG at BFM

On Sun, 5 Dec 2004 06:42:51 -0600, "Dan Luke"
wrote in
::

... so that [they] always have full tanks," which is a silly
practice unless one ALWAYS knows the next flight will require full
tanks.

The practice of topping the fuel tanks after each flight rests on the
notion that air contains a certain amount of moisture, and that the
water will condense out of the air contained in partially emptied
tanks and contaminate the aircraft's fuel system.

"Larry Dighera" wrote in message
...
On Sun, 5 Dec 2004 06:42:51 -0600, "Dan Luke"
wrote in
::

... so that [they] always have full tanks," which is a silly
practice unless one ALWAYS knows the next flight will require full
tanks.

The practice of topping the fuel tanks after each flight rests on the
notion that air contains a certain amount of moisture, and that the
water will condense out of the air contained in partially emptied
tanks and contaminate the aircraft's fuel system.

Which is an old wives tale. The amount of water contained in 20-30
gallons of air is insignificant.
--
Dan
C172RG at BFM

On Sun, 5 Dec 2004 07:40:00 -0600, "Dan Luke"
wrote in
::


"Larry Dighera" wrote in message
.. .
On Sun, 5 Dec 2004 06:42:51 -0600, "Dan Luke"
wrote in
::

... so that [they] always have full tanks," which is a silly
practice unless one ALWAYS knows the next flight will require full
tanks.

The practice of topping the fuel tanks after each flight rests on the
notion that air contains a certain amount of moisture, and that the
water will condense out of the air contained in partially emptied
tanks and contaminate the aircraft's fuel system.

Which is an old wives tale. The amount of water contained in 20-30
gallons of air is insignificant.

A Piper PA28-235 can have 84 gallons of fuel in 4 tanks, so leaving
them half empty, for instance in a humid maritime environment,
overnight where the temperature drops sufficiently to cause the
moisture to condense out of the 40 gallons of air contained in them,
will result in enough water in the fuel system to interfere with
operation of the aircraft's power plant.

However, PA28-235 can carry its empty weight (~1,400 lbs) in useful
load, so weight management through fuel offloading is seldom
necessary.

Personally, I prefer that water never be present in the aircraft fuel
system, especially in aircraft with fuel tank bladders....

Larry Dighera wrote:

A Piper PA28-235 can have 84 gallons of fuel in 4 tanks, so leaving
them half empty, for instance in a humid maritime environment,
overnight where the temperature drops sufficiently to cause the
moisture to condense out of the 40 gallons of air contained in them,
will result in enough water in the fuel system to interfere with
operation of the aircraft's power plant.

At 40 degrees Celsius, 1 cubic meter of saturated air contains roughly
40 grams of water. (I leave it to you to convert this to US units.)
Hardly significant.

Stefan

A Piper PA28-235 can have 84 gallons of fuel in 4 tanks, so leaving
them half empty, for instance in a humid maritime environment,
overnight where the temperature drops sufficiently to cause the
moisture to condense out of the 40 gallons of air contained in them,
will result in enough water in the fuel system to interfere with
operation of the aircraft's power plant.

At 40 degrees Celsius, 1 cubic meter of saturated air contains roughly
40 grams

That's about one and a third ounces. Remember, if all of the water comes out
of the air, it settles to the bottom, and is either drained or used by the
engine. It would take a lot of such cycles before enough water would be in the
tank to matter. As someone else already said, full tanks to prevent dangerous
condensation is another aviation myth.

On Sun, 05 Dec 2004 15:29:44 +0100, Stefan
wrote in ::

Larry Dighera wrote:

A Piper PA28-235 can have 84 gallons of fuel in 4 tanks, so leaving
them half empty, for instance in a humid maritime environment,
overnight where the temperature drops sufficiently to cause the
moisture to condense out of the 40 gallons of air contained in them,
will result in enough water in the fuel system to interfere with
operation of the aircraft's power plant.

At 40 degrees Celsius, 1 cubic meter of saturated air contains roughly
40 grams of water. (I leave it to you to convert this to US units.)
Hardly significant.

While the amount of water in the fuel system may be small, so is the
diameter of the fuel lines. In the cool environs at altitude, what is
to prevent the water from forming a frozen 'cork' blocking fuel flow?

Aircraft with fuel bladders that have become deformed or otherwise
lack a smooth bottom surface are capable of trapping significant
amounts of water and preventing it from reaching the fuel sumps for
removal without tipping the wings and other effort. The later model
Cessna 172s now have 10 wing drains as a result.

I submit, that water in an aircraft fuel system has the potential for
disaster. To argue otherwise seems absurd.