Re: Does B737-400/500 have dump fuel system?

Date:         20 Nov 98 02:31:00 
From: (James Matthew Weber)
References:   1
Followups:    1
Next article
View raw article
  or MIME structure

On 03 Nov 98 02:05:42 , (sun tea cho) wrote:
>Recently I know that  B737-400/500 dosen't have fuel dump system ?
>why ?

No good reason to have  it.

 On a widebody, there is a huge difference between maximum takeoff
weigh and maximum landing weight. For instance on a 777-200ER, MGTOW
is 648,00 pound, MLW is 460,000 pounds. (for a 747-400 the numbers are
875,000/630,000, MD11 630,000/440,000 lbs) If an emergency occurs
shortly after takeoff on a long haul, you have 188,000 pounds of fuel
to get rid to get down to landing weight.  188,000 pounds would take
about 11 hours to burn off. Otherwise you are looking at a vastly
overweight landing. Singapore Airlines was forced into that situation
with a 747-400. No serious injuries, but they ended up having to
writeoff the aircraft (actually it was Boeing that ended up writing it

On a narrow body like the 737, the difference between MGTOW and MLW is
very small compared to a long haul widebody

A 737-400 has a MGTOW of 138,500 pounds, and MLW of 121,000 pounds
-500 has an MGTOW of 115,500 and MLW of 110,000.

Even if you have to return to the field immediately after takeoff, you
are looking at landing weight that is at most 10% over max.. You can
often burn off the excess weight fairly quickly, there isn't much.
Overweight landing is not recommended, but unlikely to do serious
damage to the aircraft if you have to do it, it is at most 10%
overweight, whereas a widebody  could be about 35% overweight..

Airbus aircraft are a mixed bag. A300B2's are like narrow bodies,
later models are like widebodies with much large MGTOW/MLW asymmetry.

Weight data is from Aviation Week & Space technology 1998 Source book.

Hope that answers the question.