Summary
Benign though it may sound, 'flutter' is an aircraft designer's nightmare and one of the reasons it's up so early in the Boeing 787 order of flight certification issues to treat. Without unnecessarily going into the technical detail, flutter trials are the most important early element of any new program and as such, the 787 has already reached its first major milestone. All it has to do now is pass the tests, and supply chains worldwide will be holding their breath until it does...
Analysis
A highly respected aerospace engineer at a major aerospace OEM said more than 50 years ago that while, "...the wing is where you are going to fail..." (this was in the days before commercial podded engines were even thought of far less properly understood), the aerodynamic horror story that is 'flutter' was every aircraft designer's preeminent nightmare.
And if you think that's an exaggeration, how about the fact that in many manufacturers, the word was so portentous it was often never even allowed to be spoken aloud, but was simply referred to as the "F" Word...
There's nothing new under the sun, is there, Lord Voldemort?
The fact that Boeing is therefore already preparing to undertake flutter tests on the 787 is the earliest certification milestone reached after the first flight itself. Flutter can't reasonably be replicated in the lab or in the simulator, no matter the sophistication of the software the latter has at its disposal.
Flutter is a true flight-test issue, even more important than ceilings, speeds or fuel-efficiency. If and when Boeing can demonstrate to the FAA's satisfaction that the 787 is essentially flutter-free for the average line pilot to safely operate the aircraft will there be a collective sigh of relief at Boeing, echoing all the way down the supply chain corridors.
There will be other flight test milestones: none will be so important, however.
