The AD applies to all models of 737, so I "assume" they are all the same, never seen a NG.
The problem with a level switch is that in flight the crew want to be able to use that fuel, they still can now of course but MUST turn off the pumps as soon as the low pressure light comes on. Any switch could go through the air/ground sense? but a bit messy, what if that played up, could have a really dangerous situation where on a long flight, this switch system went U/S and crew could not use all that fuel in the centre?
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"I USED to be a PPRuNaholic, but now I'm CURED"