Post by Jon Monreal
I just hope that Boeing's decision to make the aircraft all-composite
will turn out to be the right one (not that I want to see Airbus lose
ground or anything, but Boeing needs some good news).
Composite bicycles have existed for some time now. At first, the forks
remained in metal allows because they didn't quite trust composites in
that shape (fork takes a lot fo stress when you hit potholes, brake etc).
But as manufacturing methods improved, they did find ways to build
bicycle forks with composites, and you don't hear about composite
bicycles breaking apart even when used on the notoriously bad Québec roads.
Both Boeing, and (especially) Airbus have been using composites for some
time now for various parts of the aircraft. Lessons were learned and
experience gained. (for instance delamination issue uncovered with the
AA A300-600 crash in Queens NY).
They didn't set out to have flaws in the Comet. They just didn't think
about stress issues in square windows. They didnt set out to have bugs
in the A320 software, but neither Airbus nor the FAA had devised testing
to ensure that changing cabin temperature would not interfere with
engine throttles. It had never been thought possible because on
conventional aircraft that was really no way for one to influence the other.
Boeing would know about the Comet, and it would know about composites
behaving differently, and I suspect that as part of its NASA research
project, it fully tested stress issues with the interface between window
frame and composite fuselage. (especially since the 787 windows are much
Quality assurance of computer software has matured to a point where FBW
systems are fairly reliable from the start.
The side-of-body issue is worrysome. If computer simulations weren't
precise enough to predict the problem, what else was not predicted
Thankfully, this is what flight testing is all about. Airbus also had to
do some tweaking of the A380 structure to re-enforce some areas found to
be weak during flight testing.
The big question is whether flight testing will uncover any problems
that may pop up 10 years from now as aircraft age.
Coming back to production: in a way, what appears to be a silly decision
to continue to produce 787 parts even though they couldn't figure out
how to make #1 work may have been a very smart one from a safety point
Alenia managed to get its first couple of fuselage plugs out "perfect".
But when it moved into production mode, it ended up producing 12 or 20
(can't remember) plugs with wrinkles in them. This is obviously a
reproducible problem and it should be easy to verify that the corrected
process will eliminate that problem. Furthermore, by producing so many
parts, one would think that any other production flaw would have been
Obviously, I personally consider the first 20 or so aircraft to be
"beta" models and would rather fly on a 787 whose serial number of
greater than 25. But if the patched up, assembled-multiple-times,
rivets-changed-a-lot-of-times aircraft #1 manages to pass the
certification tests, then perhaps the rest of the first batch of 787
will be even safer, despite being imperfect.
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