Difference between an A340-313 and A340-313X?
 

Does anyone know the difference? ie, what is the "X" for? (Did post this elsewhere without any result as of yet!)

Not my specialist subject, but I think the -313 was the original version, and the 313X is the newer 'beefed up' model.

IB operate the 313 (MTOW 260t) and 313X (MTOW 275t), so I assume the 313X's are fitted with extra long range tanks.

Could be wrong though!

What makes it "beefed up"? Accordinging to airbus.com the -200 and the -300 have the same MTOW at 275t! Help plzzzz!

X Factor
 

Could the X suggest a particular specification for an airline.

A BA LAE once told me that the -x36 on a Boeing (e.g. 747-436, 737-236) means that it was built to BA Specs.

I could be wrong so don't quote me.

It's not a customer code, like Boeing does, (36 for BAW), as there are too many airlines with them, even new airlines getting them fresh so to speak.
The 211 version, quite simply is:
(the first 2) the 200 version,
(the middle 1) engine manufacturer, 0: General Electric, 1: CFM International, 2: Pratt and Whitney, 3: IAE International Aero Engine, 4: Rolls Royce.
(and the last 1) what type of engine it has: -211 CFM56-5A1; -212 CFM56-5A3; -214 CFM56-5B3/P.
So an A340-211 is a -200 with CFM56-5A1s........I think. Still leaves me with the X models though!!!

I'm quite sure its for the filing system, as in X-files.

Sorry, could not help myself. ;)