With Boeing thinking about a 747 advanced which would use the 787s's
engines, how much changes to the 747 could Boeing make to bring the 747
in line with its 777 and 787 ?

It has often been said that changing systems in an aircraft would
require a new type certification.

But if you already have developped a{*filter*}pit for the 777 and 787, and
already have developped bleedless systems for the 787, would it really
cost so much to implement the FBW systems and{*filter*}pit as well as
bleedlesss systems into the 747 ?

If Boeing stretches the 747 while keeping the rest the same, what is to
be the difference in testing/certification compared to a real revamp of
the 747 with the systems from 787 ?

Wouldn't both have to go through flight tests period that isn't so
different ?

Is it a question of the cost of producing different documentation ?

When Boeing went from the 747-200/300{*filter*}pit to the 747-400 with 2
pilots, wasn't that a significant change to the{*filter*}pit ? how much in
terms of type certification costs/tests was required ?

Well, Boeing thought of it as an upgrade, but the European authorities
ruled it to be a new aircraft type. The major headache to Boeing is
that the /400 then had to be upgraded to meet newer standards from
which the earlier 747's were exempt. In particular, the plane was
built to survive explosive decompression from instantaneous loss of a
12x12 (foot) section of the skin, but newer regulations demanded a
20x20-foot section. The problem was buckling of the upper deck,
through which the major control cables pass. This came up just as
aircraft were first being delivered, so KLM (among others) got
temporary permission to fly the plane while Boeing worked out a
modification.

The /400 also got new engines, more wing, and winglets. It was
upgraded in gross weight. The{*filter*}pit wasn't the only change, nor even
the most significant.

--
-Stephen H. Westin
Any information or opinions in this message are mine: they do not
represent the position of Cornell University or any of its sponsors.