Wouldn't that be failures (plural) of the fuel transfer pipe, or the check valves (plural) - with neither main tank pump being able to fill the transfer pipe, and both supply tanks draining too much back into the main tank, in a nose-down attitude.
No single blockage/breakage in the transfer pipe segments between i) the aft pump, ii) the spigot for supply tank 1, iii) the spigot for supply tank-2 and iv) the forward pump should starve the supply tanks, unless only one main tank pump was submerged. From the pictures below, I can only see that working in a nose down attitude too - with the supply tanks draining back into the main tank.
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WWW.CRASH-AERIEN.AERO ? Glasgow : un hélicoptère s'écrase sur le toit d'un bar (as in post 1026)
seem to be variously accurate looking plans of the underfloor bladders.