Hi Loco. As I said, it's not something I've come across & I never really had a fuel trim problem, but there could be, in some systems, the facility to accommodate it. The only one I recall is tail fuel on the 744. Never used it ex MEL, except when pumps weren't working on an MH 744 & the thing still had fuel up there...nasty to work around.
I agree, the electric ones worked by zones too, but I mainly worked on the widebodies, not those tiny Boeings & their like!!!
