Boeing cites risks in design of newest Airbus jet
 

What Boeing are saying may or may not be true, but one would suggest that Boeing would be better spending 24 hours a day 7 days a week looking after their own airplanes and trying to get themselves out of the messes that they (Boeing) have created

This a responsibility for anyone with risk knowledge to advise the regulators of a concern. I'm all for new ideas and equivalent or improved safety as I'am sure that Boeing is as well, A black mark against any manufacturer has a tendency to affect all as well. If this latest issue can not be resolved by equivalency and history then maybe it's time for a new rule making to permit similar changes across all manufacturers

The B737 pop open overwing exits turned out to be a safe innovation done the same way

Guess I've heard everything now? Boeing doesn't trust the certification process to determine compliance with safety standards? So Boeing, who thwarted the certification efforts of FAA, EASA, TC, et al., doesn't trust them to evaluate the type design of their chief competitor. Perhaps Boeing, perhaps using all its remarkable ODA resources, wishes to become the chief worldwide regulator of transport airplanes. I am sure they would be impartial. I think I know where to file this.

I wonder, what is the difference between an integral tank and the usual integral center tanks? Boeing has some experience with those exploding, so it should have a valid input based on those experiences...

Of course there is the huge elephant in the room, that B has absolutely nothing to offer in that specific, and very narrow, market segment.

If my understanding is correct, Airbus proposes to use the skin of an aircraft has a tank wall. Been tried before with ships and was a huge environmental disaster.
Airbus has previously used ACT (Additional Centre Tank) in cargo bays. They were a feature in the long range versions of the A310.

Any different to a wet wing?

In principle, no: but rather closer to the passengers

So first it will feel too cold and then too hot?

Even without Boeing's unhelpful intervention, there seems to be a good chance that Airbus will get its fingers burnt (npi) by the additional conditions that EASA said some time ago that it will impose in respect of the RCT.

There will no doubt be a technical solution to the issues, but anything that adds weight and/or reduces RCT capacity will have implications for the XLR capability and not be popular with customers.

and nearer to the ground, which would give rise to the elevation of risk identified by Boeing in the event of off-piste excursions or gear failure

Not the wing but the fuselage .
Some years ago I few an innovative aerobatic aircraft where the fuel tank extended in the space between my legs. This was supposed to be a brilliant engineer idea to keep the aircraft as aerodynamic as possible and the most weight close to the CG . A brilliant idea indeed on paper but having only a few millimeters between your most valuable parts and a plastic fuel tank made sure I did not renew the experience. The aircraft never went beyond experimental.
Sometimes what looks like good ideas fail to succeed in practice. I hope this one does too. ..

How is this significantly different to any aircraft with a centre fuselage tank? We rarely used the A330 centre tank, but many long-haul aircraft have them. Some A321s have extra tanks in the cargo holds - under the floor.

It seems that Airbus are proposing to mould the centre tank more closely into the space to create extra room in the tank? A bag tank would be slightly compromised by not fitting exactly snugly around every rib and contour that it rests against, losing space in the tank.

Presumably installing a composite/plastic tank, then heating and pressurising it in situ so the tank walls push out and exactly fit the metalwork surrounding it like a glove, will increase the volume inside the tank slightly for a little more fuel. Once thus fitted, the tank would be allowed to cool and harden off in its new snug profile?

Boeing clutching at straws, trying to divert attention away from their disastrous recent history.

Didn't Concorde have quite a few fuselage tanks that were able to recently get recertified with the final modifiation package by Airbus?

Well, Boeing would know all about fires with the 7-late-7 batteries and the 747 centre tank explosion some years ago.....

Airbus has been using additional tanks for years; the A310MRTT has 4 additional centre tanks shaped to replace pairs of cargo containers. No problems whatsoever!

Even though I do agree, Boeing doesn't exactly have the high ground here, there are some serious problems with this idea.
Centre wing tanks tend to be made from rather more robust and thicker material than fuselage skins.
I think D.C-10s have aux tanks in lower fuselage area, but not integral to the structure.
Yes, Concorde does have fuselage tanks. There were quite a few elements of the Concorde design that would probably not get regulatory approval today.
Airbus needs to rethink this. Stab/fin tanks perhaps? Doesn't the A300 have a tank in the fin?

Both the A300 and A310 have 'trim tanks' in the tailplane, not the fin.

Turin,
The MD-11 also has an AUX tank which is used for ballast fuel purposes.

Also the A330/A340 both have a horizontal stabilizer fuel tank within the Stab front and rear spars.

What is the structural difference between this new center tank and the center tank already in all B737, B777, A320, A321 and A330-200 aircraft? Is there something that makes this particularly more vulnerable to failure than previous center tanks? If anything I would have thought an integrated center tank as proposed for the XLR should provide improved safety over the removable ACTs used currently in the LR?