Post mortem on an IEC connector

That's why they have rules called ETOPS.

Graham

-- due to the hugely increased level of spam please make the obvious adjustment to my email address

Engines ? BA flew one from LAX to MAN on 3 engines, one having failed after take-off.

The FAA didn't like it much and made a big fuss but concluded it was within the regs.

Graham

due to the hugely increased level of spam please make the obvious adjustment to my email address

Three potentially *redundant* engines is what I said. The 747 is capable of still remaining airborne and controllable, with just one motor running, as far as I am aware.

Arfa

TWO IIRC, A 747 will be descending on one, so the redundancy on twin engined airliners is pretty similar esp since they have more modern and reliable engines.

Graham

-- due to the hugely increased level of spam please make the obvious adjustment to my email address

Whatever. Even if it needs two to maintain level flight, that's still two out of four, which leaves two that can be out, which is better than two going out on a two engined plane. I would still prefer to have just one out of four running, even if that did place the plane in a descent configuration. At least, coupled with the substantial glide characteristic, that descent is going to be very slow. As to how modern and reliable engines are, that doesn't really mean a lot if you have say multiple bird strikes.

I spoke to my aviator friend yesterday about fly by wire incidents, and he says that he has read of many, although ones that have resulted in a large scale catastrophe, have been fairly rare. As to pilot error being "the biggest cause of accidents", he said that you should be careful how you interpret the numbers on this, with respect to other published causes. He agrees that many incidents are pilot related, but he also said that it is nothing like the TV program "Air Crash Investigation" where every crash gets resolved to a wrongly fitted bolt or whatever, and that many incidents never have a real cause determined. In these cases, apparently, it is normal to log the (probable) cause as 'pilot error'. He also said that just about all training accidents, of which there are apparently many, are logged as 'pilot error', so one way or another, this distorts the figures against the true situation.

Arfa

The A320 has been using the CFM56 powerplant since its been flying. Boeing uses a variation of it (different thrust) in their 737 stretch models. All are based on General Electric's military core high end compressors, combustion and turbine. CFMI makes 6 models all designated CFM56.

I'm certain the original models probably the CFM56-A weren't scrapped but rather retrofitted with redesinged controls to allow quicker throttle up response at low altitude. After all the core of the engine was designed for the US B1 bomber and F-108 fighter so it wasn't a design flaw of the entire engine.

You seem remarkably well versed in all this, Meat. Very informative info. Did you have a career background in it ?

Arfa

I watch a lot of educational TV. Military Channel, Discovery, History, National Geographic, Science channel. Also have a friend who flies the Airbus now training on the Boeing 767 and talked to him about the Mulhouse 320 crash. He said that the automatic go around program was canceled on the flight system and it wasn't a throttle response issue. Well at least that's what the Airbus folks told him :) Personally I believe there were many factors involved that neither side are or will ever be willing to fully disclose because of the popularity of the airframe. Remember this was very early in the 320-100's career and I'm sure there were some bugs in the flight controls. I don't think it was pilot error. If you look at the video the pilot tried to correct with a nose up attitude but the engines failed to spool until it was sucking tree tops.

How do you make a Faraday cage out of GRP? without making it as heavy as the metal you are replacing.

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

the

According to my paper , no Faraday cages these days. Apparently "static wicks", wires buried on the edges of wings and tail is supposed to do the job that an overall shell of aluminium used to do.

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

Yeah, I know what you're saying. It just bothers me a little that on say a

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

It`s some kind of light wire mesh laminated into the CF. General chat on the PP forum would suggest that composite based airframes seem to attract lightning more than aluminium clad ones do.

Ron(UK)

From reading the boards, it appears that, rather than flowing arond the outside of the aircraft, lightning is more inclined to punch holes right through composite skins, thereby getting into the metalwork and wiring.

Ron(UK)

there

as

the

Suely its not whether they attract, that is how lightning conductors work. But how easiily the current passes around the frame and out the other side, with as little ohmic heating on the way, to continue its cloud to cloud path.

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

So, perhaps not the best choice of material to make a long haul aircraft from, given that it is going to fly to areas of the world where thunderstorms are prevalent, and at cruising altitudes where it is well up amongst the crap, as it were.

I have actually flown in and out of both Orlando and Las Vegas, with thunderstorms in the area, without giving them a second thought. But then that was in a nice 747 aluminium cigar tube ...

If it is true that CC skins are not good in areas of electrical storm activity, I'm sure pilots regularly flying such planes, must be aware of this, so if the weather radar on this flight showed that he was heading into bad air and storms, I wonder why he didn't go around it, or see if it was possible to climb above the worst of it ? I understand that thunderheads can extend above the maximum ceiling of airliners, but I would have thought that there might have been a 'way through' between cells ? Fuel constraints maybe ? Looking on a map, the path from Rio to Paris looks awfully long for a plane of this size.

BTW, is that Ron ex LVA ? If so, you haven't by any chance got a schematic set for a Warwick Sweet 25.1, have you ? Or anyone else reading this ? Warwick have refused to even acknowledge requests for assistance, let alone supply info.

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.

That might be true if the skins of Airbus aircraft were made completely of composite materials. But the truth is the wings and fuselage are made of aluminum panels sandwiched with composite materials inside. Logic dictates that a bolt of lightning with a gazillion Joules of energy will no more impact an aircraft surface of 100% aluminum than it would with a aluminum outside and composite inside. Lightning just isn't that picky.

It's part of our plan to take over the world. Rather than stopping North Korea from building nukes, we're just going to make sure they're RoHS compliant.

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