bluskis
According to the latest issue of Aviation Week, sufficient fuel must be kept in tanks equipped with the affected Crane Hydro-Aire pumps to keep them submerged. This fuel cannot be used in flight nor can it be planned to be used during preflight planning.
It increases UNusuable fuel by 1000 pounds in the 737 and 757's and by 3000 to 7000 pounds for 747's. 747-400's are prohibited from using the optional horizontal tail tank, until pumps are inspected/replaced.