Re: Question: Fuel Dumping

Date:         21 Jan 97 01:32:27 
From:         "Brian A. Reynolds" <bareynol@cca.rockwell.com>
Organization: Rockwell Avionics - Collins
References:   1 2 3
Followups:    1 2
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Pete Finlay wrote:
>
> In article <airliners.1997.80@ohare.Chicago.COM>, michael.f.lechnar@boei
> ng.boeing.com writes
>
> <<other stuff snipped>>
> >
> >The main reason that fuel jettison is used is to meet the FAR 25 requirements
> >for approach climb and landing climb gradients.  A side benefit to landing at
> >a lower weight is less stress on the airframe.
>
> Well, you're *nearly* right, but not quite. The main reason for dumping
> fuel is for us to get the aircraft down below max. landing weight as
> soon as possible. Secondary to this is that the lower the weight, the
> lower the approach speed, which is important in landing with flap/slat
> malfunctions.
>
> You've got to bear in mind that nearly all big airliners take-off at a
> much higher weight than they can land at. Therefore, if you have to land
> earlier than scheduled, due an en-route diversion, or an emergency after
> take-off, you invariably need to dump fuel down to below landing weight.
>
> AFAIK, the 'approach climb', and 'landing climb' don't enter into it
> (whatever they are)

Hi Pete, sorry, have to agree with Mike.  FAR 25.1001 Fuel jettisoning
system.  (a) A fuel jettisoning system must be installed unless it si
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 thte same as that used in
meeting the applicable takeoff, approach, and landing climb performance
requirements of this Part.  Landing gear is addressed in 25.721 and the
requirements deal with the adequacy of the landing gear, reserve
capability, and testing.

It is my understanding that Airbus aircraft do not have the capability
to jettison fuel.

Brian