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MD-80 Balance

Sat Dec 02, 2000 1:46 pm

How do they balance the weight on the MD-80 with a 2, 3 configuration? Is this a problem? If so, how is it corrected? Thanks.

RE: MD-80 Balance

Sat Dec 02, 2000 8:15 pm

I went on md-83's in the early 90's with airtours.
I seem to remember passengers being moved to different seats before takeoff. Having said that I cannot even remember the seat configuration being 2 - 3.
Posts: 330
Joined: Sat Dec 02, 2000 5:48 am

RE: MD-80 Balance

Sat Dec 02, 2000 8:23 pm

That´s correct! Normally you move passengers to correct the arm! I don´t know exactly how it works with the MD-80, but on the aircraft I fly (Fairchild Dornier 328-110), we have problems with the weight and balance specially on those aircrafts wich are not equipped with an APU. Those planes are pretty Nose heavy. When you dont have much baggage wich you can put in the rear baggage compartment you have to move the PAX to the back.

Sincerly, Benjamin!
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RE: MD-80 Balance

Sat Dec 02, 2000 8:26 pm

What happened if all the seats are occupied? Then the weight distribution will be more or less equal.....

Just a thought though....

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Joined: Sat Dec 02, 2000 5:48 am

RE: MD-80 Balance

Sat Dec 02, 2000 8:36 pm

That´s not correct completle! On my aircraft we have for example a DOI ( dry operating index ) of 60. Then on our Loadsheet we have two stations for the baggage compartment, wich is in the rear. For every 50 kilogramms we shift the index for about to stations.
So we have two CPT for the baggage, the two for the passengers, and then the central CPT where there is no change of the Index because it´s under the wing. And than we have two CPT for passengers again. So there are 4 CPT wich shift the Index to the rear and only 2 wich shift it to the front.
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RE: MD-80 Balance

Sun Dec 03, 2000 1:18 am

Left/Right weight distribution has no noticable affect on MD80/90 weight and balance. Yes it has an affect, but the moment arm is simply too small for that affect to be noticed by pilot. Front/Back weight distribution has greater affect since the moment arm is much larger. When departing with extremely light pax loads, weight/balance becomes important on the short flights (little fuel loaded) I fly. Occasionally (maybe once every 2-3 months) we load 5000 lbs. of ballast fuel in the center tank (move center of gravity forward) to ensure aft CG limit is not exceeded. That 5000 lbs. ballast fuel is also required when towing empty aircraft with light fuel load.

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Joined: Sat Jun 12, 1999 12:01 am

RE: MD-80 Balance

Sun Dec 03, 2000 8:11 am

One of my pilot friends used to fly MD-80s for Alaska, and I asked him this same question. He said it has no effect on the balance. He now flies 737-400s, and says that they are easier to tail scrape than the MD-80, which was suprising!!! Hope this helps.
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Joined: Fri May 28, 1999 4:12 am

RE: MD-80 Balance

Sun Dec 10, 2000 5:00 am

Even an empty MD80 is heavier on the right landing gear, because some fuel pump devices, weighing some 500 kgs, are placed right of the CG centerline.

This is not a problem in comparison with the front/back arm; consequences have been described above. The MD87 has a 30 cms (1 ft) higher tail-fin to compensate for a change in momentum arm, when the fuselage was cut short from the standard MD80.

In general the MD80/90 is very light on the nose-gear with only some 1-1.5 metric tonnes weight on it when empty. Scandinavian SAS fly around with 350 kgs of gravel in sacks in the front hold of the MD90's to balance the plane when empty, since they opted to buy the planes without the built-in retractable front stairs set.

Jan-Erik Andelin
MD80 International Forum

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Joined: Mon Jan 17, 2000 12:45 pm

RE: MD-80 Balance

Sun Dec 10, 2000 6:31 am

When you think about it, the uneven seating has almost no effect on the aircraft. There are 2 seats against each wall of the cabin. In the very middle, you have a seat and the aisle, variable depending on the airline. So it only varies in the very middle of the aircraft.

The Piaggio P-180 Avanti, when loaded with only two people in the cockpit (even with full fuel), lifts one wheel of the nosegear off the ground during sharp turns. You have to pay attention to it and avoid really tight turns when lightly loaded.

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