Re: Boeing naming convention for 777

Date:         16 Aug 99 19:02:52 
From:         James Matthew Weber <jmweber@goodnet.com>
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>Boeing's web page lists the MGTOW range for the 777-200(ER) as being
>from 580,000 lbs up to 656,000 lbs.  UA has some of the first ones built
>and theirs are all good for 632,500 lbs -- not the heaviest, but a lot
>closer to the top of the scale than to the bottom.

Actually AvWeek shows the base -200 has an MGTOW of 545,000 pounds And
Unless UA paid for some substantial mods, I doubt their 'A' models have
been upgraded to 632,500. That was in fact the initial MGTOW on the 'B'
Model.

>So far as I know, it really is just a paper upgrade as far as the
>airframe is concerned.  You might need to upgrade engine thrust, but
>the AW&ST Source Book has identical physical dimensions and weights
>for the range of 777 engines from any given engine manufacturer so
>I'd guess that even that is little more than a paper upgrade -- you'd
>need to change the programming of the FADECs or something similar.

There is in fact a 4,000 pound difference in empty weight between the A
and B versions. That is a lot of paper!  The Change from A to B also
involved strengthening several areas of the aircraft (about 4000 pounds
of metal),  however the upgrade from any B configuration certified
weight  to a higher B configuration weight requires a check payable to
Boeing, and in return you get a Floppy from Boeing that updates the FMS.

For instance the GE powered BA 777-200ER's were purchased with MGTOW
well below the 632,500 pounds available at the time. Many charges are
weight based, and unless you are operating the aircraft at extreme
range, the additional weight may not translate into revenue, as payload
will be limited by landing weight rather than takeoff weight. My
recollection is these BA Aircraft are certified at about 590,000 pounds.
Emirates had the certified weight of their 777-200ER's reduced. On their
route system they didn't need the full weight, and it reduces the
transit charges over some countries on the route system.

Increases from 632,500 pounds to the current  656,000 pounds were
apparently accomplished by changing the CG limits rather by structural
changes, this has the effect of reducing structural loads, so that one
really is paper.

James Matthew Weber   (623) 587 7514 .  Fax  (623) 434 7598