JetDoc,
Thanks for the tech info. I am not sure that the pump inlet screens would be relevant to my argument , but if the three wing tank pumps ( fwd/aft/jettison) all have a fuel AND airtight NRV at the outlet, my suggested possible scenario is invalid.
Why would the wing tank jettison pump need an NRV? Everything is going overboard anyway............
Can you show the schematic with the NRV in the line?