Why can't the French dump fuel?

As to why no provision for fuel dump, I suspect it is a cost driver:

Of course, everything is a cost driver. Whether or not to have carpet
is a cost decision. The real question is what the benefit side looked
like in their cost/benefit talks.

-Robert

Put another way, why provide a way to dump fuel when you can just run it
through the engines.

They didn't need to lose weight that fast, they didn't need to land 'right
now'. The fact that they flew around in circles for three hours was probably
a good thing, time to examine every possibility and double check everything
before landing.

"Robert M. Gary" wrote in message
ups.com...
As to why no provision for fuel dump, I suspect it is a cost driver:

Of course, everything is a cost driver. Whether or not to have carpet
is a cost decision. The real question is what the benefit side looked
like in their cost/benefit talks.

-Robert

"Mike W." wrote in message
...
The fact that they flew around in circles for three hours was probably
a good thing, time to examine every possibility and double check
everything
before landing.

(OT!) I thought they just flew around for a 3 hour tour as a tribute to a
late actor...

"Robert M. Gary" wrote in message
ups.com...
As to why no provision for fuel dump, I suspect it is a cost driver:

Of course, everything is a cost driver. Whether or not to have carpet
is a cost decision. The real question is what the benefit side looked
like in their cost/benefit talks.

Why is dumping fuel needed? It can still climb at engine out with full
fuel, no need to dump there. If they can get up, and stay up, no need to
dump; they are safe.

What in this case? Were they in danger, flying around? No? Why dump,
then? Could they have landed immediately, in a case of immediate danger?
Absolutely. Still, you are asking. Why would they need to dump? They were
in no danger.
--
Jim in NC

("Morgans" wrote)
What in this case? Were they in danger, flying around? No? Why dump,
then? Could they have landed immediately, in a case of immediate danger?
Absolutely. Still, you are asking. Why would they need to dump? They
were
in no danger.


Then why not fly on to London, er...NY?

I wonder how far they would have gotten at half speed ...Iowa?


Montblack

Robert M. Gary wrote on 9/27/2005 14:07:
In the case of the A320, or the 737, they can both land with a full load

of fuel.

Then why did Jet Blue fly around for 3 hours burning fuel before
landing back in LAX?

The last link provided by Kev has the likely answer:
"The primary reason to burn off the extra fuel was that a heavier plane
has a faster landing speed. Since a slower airspeed on landing was the
objective in this case, the course of action was to lighten the load by
burning off some fuel and when landing, lower the nose gear at as slow
an airspeed as possible."

-Joe

The last link provided by Kev has the likely answer:
"The primary reason to burn off the extra fuel was that a heavier plane
has a faster landing speed. Since a slower airspeed on landing was the
objective in this case, the course of action was to lighten the load by
burning off some fuel and when landing, lower the nose gear at as slow
an airspeed as possible."

Joe,
You sound like an EXCELLENT advocate for having the ability to dump
fuel too!!!

-Robert

The FAA certification requirement for a fuel dump system is a takeoff
weight that is greater than 135% (I think) of the max landing weight.
They don't add the complexity and cost of a dump system unless it is
required for certification.

The 707-123 I flew had a empty weight of 120,000 lbs, max TO weight of
256,000 lbs, 112,000 lbs of fuel, a max landing weight of 190,000
pounds,(135%) had a dump system. A 757-200 at 256,000 lbs carries
83,000 lbs of fuel, max landing weight of 198,000 lbs (130%) does not.
BTW the 757 with 29,000 lbs less fuel has the same range as a 707-100
with the same passenger load.

The 707 system has standpipes that let you dump only to get you down
to max landing weight, leaving in our case about 70,000 lbs of fuel.
That being said, I'd have flown around several hours after dumping, if
there was no immediate emergency , to get as light and non-flamable as
possible before landing. Their gear problem was not an emergency and
I doubt the crew declaired one even though they asked for the
equipment. Emergencies require immediate action. (think fire) BTW a
single engine failure is not classified as an emergency either. The
aircraft is certified to climb at max takeoff weight on a single
engine.

I'm sure the airlines, EPA, and everyone else would rather the fuel be
burnt as normal rather than dumped into the air and sea. In an
emergency, planes that don't have a dump system will do an overweight
landing and and have to do an overweight landing inspection prior to
next flight. Given the choice, it's better to burn it down than do
the inspection.

Don Hammer wrote

The FAA certification requirement for a fuel dump system is a takeoff
weight that is greater than 135% (I think) of the max landing weight.
They don't add the complexity and cost of a dump system unless it is
required for certification.

Don, the rules have changed since you and I flew those old Boeings. :-)

Section 25.1001: Fuel jettisoning system.
(a) A fuel jettisoning system must be installed on each airplane unless
it is shown that the airplane meets the climb requirements of §§25.119
and 25.121(d) at maximum takeoff weight, less the actual or computed
weight of fuel necessary for a 15-minute flight comprised of a takeoff,
go-around, and landing at the airport of departure with the airplane
configuration, speed, power, and thrust the same as that used in meeting
the applicable takeoff, approach, and landing climb performance
requirements of this part.

(b) If a fuel jettisoning system is required it must be capable of
jettisoning enough fuel within 15 minutes, starting with the weight
given in paragraph (a) of this section, to enable the airplane to meet
the climb requirements of §§25.119 and 25.121(d), assuming that the fuel
is jettisoned under the conditions, except weight, found least favorable
during the flight tests prescribed in paragraph (c) of this section.

(f) For turbine engine powered airplanes, means must be provided to
prevent jettisoning the fuel in the tanks used for takeoff and landing
below the level allowing climb from sea level to 10,000 feet and
thereafter allowing 45 minutes cruise at a speed for maximum range.
However, if there is an auxiliary control independent of the main
jettisoning control, the system may be designed to jettison the
remaining fuel by means of the auxiliary jettisoning control.


Bob Moore
ATP B-707 B-727
PanAm (retired)

Bob Moore wrote:

25.121(d) at maximum takeoff weight

This is how it was explained to me; an ex-member of our club that flies for
"a major" simplified it to "one-engine-out missed approach": if the plane
can do that at t/o weight, no dump system required.

This is distinct from the maximum landing weight, which involves other
factors. In an emergency, therefore, a pilot might need to make an
"overweight landing".

- Andrew