B773 & B773ER fuel tanks

[Betsy & Nikki]

Just after some facts between the two aircraft model types.

My understanding is that the 773 has 3 fuel tanks (x1 CWT and x2 Mains) giving a total fuel capacity of approximately 137,500kgs or 171,190L

I have read that the fuel capcity for the 773ER is greater, approximately 145,000kgs.

Does the 773ER have more fuel tanks or have the existing fuel tank volumes been increased?

[singleseater]

The ER has the same 3 fuel tanks. They have managed to find a bit more room in them.
Primarily the wing tanks, they have incorporated the space allocated for the wing fold mechanisim, as nobody has even thought of taking that option up.
( yes, the original design has space for a wing fold system, apparently there was concern re fitting the A/C into some parks)