"Meat Plow" wrote in message
...
On Tue, 2 Jun 2009 10:49:57 +0100, "Arfa Daily"
wrote:





Seems that today, an Air France Airbus A330 en route from Rio to Paris
with
238 people on board, has gone down without warning over the Atlantic.
Hard
to see what the pilot might have done wrong with the thing at 38000 ft
in
the cruise ...

Apparently, it disappeared off African trans-atlantic ATC radar, at
around
3am, our time.

This is not instilling a lot of confidence in me, regarding flying on
one
of
these things in October, instead of my usual Boeing ... :-|


Electrical and turbulence problems reported. Aircraft was sending
distress signals so it may have made a decent ditch. Air France's last
air disaster was the Concorde in 2000.

I've flown the 320-100 several times and the Mulhouse crash never
entered my mind. We actually had a 5 hour delay one time after a
hydraulic pump failed on the ground and had to be replaced.

I wouldn't worry about the 330 considering the number of those things
in the air at any given time and it's wonderful track record.

Yeah, I know what you're saying. It just bothers me a little that on say a
747, the driver has got a triple redundancy control system which
hydraulically links his yoke and pedals directly to the control surfaces,
and a robot driver that can be thoroughly switched off, such that in an
unusual set of circumstances, a quick-thinking and experienced guy sitting
behind those controls, might be able to recover a potentially catastrophic
situation by thinking outside the box, and doing something which maybe
puts
the airframe outside of the 'safe' envelope. From what I can understand of
the FBW systems, they are never going to allow you to do this, and in the
event of a total electrical systems collapse, your little joystick, and
the
computer(s) that it's connected to, are not going to be of any use to
control the aircraft, anyway.

My pilot friend rang me yesterday when all this was going down (honestly,
no
pun intended). He felt that there had to be more to it than just flying
into
a storm. He says that in general, if lightning hits an aluminium-bodied
plane, it tends to pass around the outside, and re-discharge and carry on
its way from the opposite side or wherever. He questioned whether the same
would happen on a carbon composite bodied plane, as the A330 apparently
is,
or whether the higher electrical resistance of such a material, would
cause
the lightning to 'stick around' as it were, and just fry the internal
systems, or even heat the material to the point where it just exploded. He
reckons that unless there was an absolutely catastrophic failure of the
airframe, a distress signal should have been able to be broadcast almost
all
the way down, as the last voice transmitter is battery powered to ensure
that it can still operate, even in the event of a catastrophic electrical
or
systems failure. Sobering thoughts ...

Arfa


Nah the Airbus is Aluminum skin sandwiched with carbon fiber
inside.The same 'Faraday" effect applies.

If I were to fly the 747 I would surely think of the design flaws that
caused the fuel tank to explode on Flight 800. Or the one where the
rear section cracked and lost pressure on the dome that seals the rear
end of the fuselage. No I wouldn't enjoy flying through an electrical
storm in any aircraft but I wouldn't be any more worried in an Airbus.

Military aircraft with complete fly by wire don't seem to have
problems with electrical discharge on the skin. I can imagine say an
F/A 18E flying at mach two encountering some extreme static
electricity from the friction of air and water molecules. One can only
wonder how many Joules develope on the aircraft's skin.

Hmmm. I wonder if a couple of sheets of Bacofoil glued on a vaguely
conductive piece of plastic-y material, is actually as good a dissipative or
deflective surface for lightning, as a 5mm thick fully metal skin ? I have
watched the programmes on both of the crashes that you quote, and I agree
that they give a (small) degree of cause for concern, but at least they were
both pinned down to exactly what caused them, and I would think that
suitable protective measures were put in place to prevent a recurrence.
Considering the size of the 747, and the number of years that the basic
design has been flying now, I think that it has proven to be a fantastically
reliable and safe aircraft.

Still, apparently, they have now located some wreckage 400 miles out into
the Atlantic, so I guess that they have around 28 days left to locate and
recover the CVR and FDR boxes, which apparently are likely to be lying in
around 13000 feet of water. Seems like the batteries for the pingers are
good for about 30 days, and the transmitter is just about man enough to get
a signal through 15000 feet of salt water. I guess that if they can recover
them and they continued to function for any time after the initial 'event',
then we could know quite quickly what the primary cause of it going down
was.

Arfa