Boeing is literally caught between a rock and a hard place. Their failure to adhere to quality standards in pursuit of financial gain has lowered their authoritativeness. However, they are experts and who should know whether a proposal is a wise option but the experts working on designing, building and developing aircraft? The concerns they raise are certainly valid and not inconsequential.

It is inevitable that these concerns will be seen as a spoiler and there is almost certainly an element of that in Boeing's comments. This has to be accepted as part of the environment Boeing and Airbus operate in - it is highly competitive and if one can legitimately delay or even scuttle a threat to one's market share then one should. One would certainly expect Airbus to do exactly the same if the boot were on the other foot.

This is not a good PR move for Boeing but it is one that needs to be made - even though their motives might be suspect they are still raising what is a valid safety issue and doing aviation in general an important service.

Anyone seen the design for the conformal tanks?

I assume like others have said they will be part of the wing to body fairing.

Similar to the F15/16 & 18

https://en.m.wikipedia.org/wiki/Conformal_fuel_tank

CCA;11006266]

"Anyone seen the design for the conformal tanks? I assume like others have said they will be part of the wing to body fairing. Similar to the F15/16 & 18"

No, that's not the case (and I don't think anyone here has said that it is).

"Conformal" here is being used in the sense that the RCT occupies the entire cross-section of the fuselage below the floor beams and so differs from a conventional rectangular-section centre wing tank.

Might not have been the best choice of adjective, feel free to suggest an alternative. :O

Just wanted to be clear as others had said that it’s not a tank that’s installed in the cargo areas.

The 747-400ER has a option for one or two additional tanks in the forward cargo and there’s very little dead space outside the cargo area. The water tanks used to be installed on the front of the CWT but were relocated to aft of aft cargo. How much space is available on a A321 outside the cargo area?

Boeing complaining means it must be fairly radical or something they can’t benefit from.

Quote from the article. “Into the fuselage” is a little generic not much space that isn’t already occupied by design.

The only other option is empty space that isn’t part of the cargo section forward of the CWT? Top of the CWT under the floor usually has space but has also historically been filled with air conditioning filters. (747)

pictures would be good 😃

Pictures and description from Boeing’s own magazine re cargo tanks for what it’s worth.

http://www.boeing.com/commercial/aeromagazine/aero_21/747E.pdf

CCA

"Just wanted to be clear as others had said that it’s not a tank that’s installed in the cargo areas."

Well yes and no. :O

The RCT does indeed occupy part of the space that in the non-XLR A321 is used for cargo or, optionally, for the removable ACT(s) in the A321LR.

The difference is that, while the ACTs are able to be removed, the RCT is permanently built in to the aircraft, and thanks to its shape the single RCT holds more fuel than 3 ACTs combined while sacrificing less cargo space.

Got it, a permanent structure built aft of the wheel well from the lower skin filling the lower bilge area up to the main cabin floor beams. Elegant.

Capacity is more like 2 ACTs. Another optional ACT can be installed in the forward hold.

Less Hair

"Capacity is more like 2 ACTs. Another optional ACT can be installed in the forward hold."

An ACT holds just on 3,000 litres. The RCT holds 12,900 litres.

My calculator reckons that's more than 4 times as much.

Boeing are within their rights to flag a potential risk from anywhere in the aerospace industry, however, whilst aimed at Airbus, it's more likely the real intent was to make EASA aware that the rest of the industry is watching.

321XLR is an excellent piece of kit, it's a (well) proven and respected design, with some relatively uneventful upgrades it's still a top tier performer and giving it the extra range makes it very desirable with longer, thinner routes becoming the new norm..

I have no doubts that it will gain EASA approval, whether in the proposed format or in an EASA specified format.

It is substituting the two ACTs in the back leaving more cargo space there while the front ACT can still be installed. Total fuel, range and MTOW will be above the LR obviously.

Less Hair

"It is substituting the two ACTs in the back leaving more cargo space there while the front ACT can still be installed."

Indeed it can, if the A321XLR's projected 4,700 nm range isn't enough for customers.

It is a rather obvious point. But Boeing is a large complex global business with 3 major subdivisions loaded with Engineers with various levels of experience in aircraft systems and aircraft design.
An aircraft design is published for comment and is circulated around the engineers in Boeing. Somewhere in a lonely cube an engineer reads the design from Airbus and think that it doesn't look 'safe'. So that engineer raises the concern through the channels of Boeing. After a suitable length of time the comment percolates to the group who deal with Boeing <-> Airbus and FAA<->EASA comments. the group puts the response into the agreed format for comments and publishes the comment.

What would the 'get back in your box you broke the 737 commenters' have Boeing do? Sit on the comment from an engineer nothing to do with the 737 and who had spotted a real problem? So what happens if that problem turns into a loss of life crash and the get back in your box you broke the 737 commenters hear that Boeing sat on one of their engineers comments for 'political' reasons that could have helped prevent an Airbus loss of life crash? They would go after Boeing again questioning their lack of an open and non-commercial approach to flight safety.

Seems like Boeing had no option but to pass the comment on - and do not think for a moment that the thought processes above were not considered prior to release of the comment. I would not be surprised at all to hear that informal comments were shared prior to the official comment. Teams from Boeing work with Airbus and vice versa. There is a LOT of coopertition.

Agree Dave Think of all the crashes which were catastrophic but no fire in particular BD at Kegworth. The slightest rupture of the aircraft skin which is inevitable in a crash would presumably release a great deal of fuel? Sometimes I wonder if the human race has forgotten that we got where we were by learning from mistakes of the past!

At least the A340-500 had a wet wingbox, with a center gear strut below pointing at it, and even this could get certified.
https://images.app.goo.gl/rw71hjpaa1A5Qe9a6

Maybe Boeing should check the safety of Airbus jets and Airbus can inspect Boeings, rather than each company inspecting their own planes. It seems they're highly motivated to find problems in their rival's aircraft, whilst no so much so when looking at their own.

Love it Peter! A contrarian’s approach to a problem.

Chris2303

You'd wonder how Boeing have the time to do Safety Audits on other manufacturers. In order to do a correct assessment Boeing would need all the production drawings and tech specs. Now if the FAA made the comment I'd probably listen more carefully!

You don’t need to see records to say “hey that doesn’t look right” when you see a fuel tank design that goes right to the fuselage skin around the bottom of the airplane......

Like I said in an earlier post if the original conformal tank design goes in unchanged then Airbus can tell Boeing to piss off. But if there are significant changes before it is approved, a situation I think is highly likely, then Airbus’s attempt to smoke this pass the regulator was properly called out.

This in no way absolves Boeing of their culpability in the MAX fiasco, it instead shows how deep the
rot is in aircraft certification goes for both the FAA and EASA

A321 XLR Fuselage Fuel Tank
 

Looks like Airbus's attempt to smoke through the extended range fuselage center aux tank design has been stopped by the FAA. The traditional extra baggage bay tanks won't work because they would use up too much room, so Airbus designed a new center section tank that goes right to the fuselage skin on the center belly in order to be big enough to hold the required fuel.:=

Airbus tried to skate over the obvious issue of what would protect the tank in the event of a belly landing and got EASA to approve it anyway. Now looks like FAA will require major structural changes to provide tank protection. I think the MAX fiasco has forced the FAA to start being more authoritative when asking skill testing questions and this new unwillingness to just rubber stamp the manufacturer's data will become standard for all regulators

It will be interesting to see what EASA does about the MAX dash 7 ands10 certifcation.....

It looks like everything got settled already before the FAA green light. The XLR problem "suddenly" surfaced and might now be done with a little liner or similar while the MAX gets rubber stamped, no EICAS needed.