Narrative:

We were doing our cockpit set up checks and preparing to leave airport to go to rjaa. We received the service form from the cockpit printer stating next to lavatory service was not available. We normally see 'completed' after lavatory; so we called and asked them to look into it. After a short time; they responded that not available was entered in error; and that we would receive a new service form. We did; and on the new service form next to lavatory stated completed. The relief pilots stated that the gauges by door 2R looked good. After about 3 hours into the flight; the purser called stating that the left side of the aircraft lavatories and the forward upper deck had stopped working. We called dispatch and maintenance to try to diagnose the problem. We tried to reset the tank that was full but could not. We knew the biggest lavatory tank was full; but did not know for sure how long we could fly before the other tanks would eventually fill up. We made the conservative decision to land at an enroute airport before a bad situation got worse. We had to dump 62;500 pounds of fuel at FL320 so we would not land overweight. The approach and landing was normal and below maximum landing weight. The lavatories were serviced. The people that serviced the airplane said that the main tank was full; but the other three tanks were about 10% full. The indicators at 2R showed more than 10%; but were they accurate? I don't know. When the lavatory service was completed and the aircraft was fueled; we proceeded to rjaa. What went wrong that led to this problem? I don't know. On the surface; it looks like everything was done right. We received a completed service form. The relief pilots said the gauges looked good. What else could we have done? Was there a problem with the gauges? Was there a problem with the person dumping three tanks; not four?

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Original NASA ASRS Text

Title: B747-400 flight crew reported a divert due to lavatories not being serviced properly prior to departure.

Narrative: We were doing our cockpit set up checks and preparing to leave airport to go to RJAA. We received the service form from the cockpit printer stating next to lavatory service was not available. We normally see 'completed' after lavatory; so we called and asked them to look into it. After a short time; they responded that not available was entered in error; and that we would receive a new service form. We did; and on the new service form next to lavatory stated completed. The relief pilots stated that the gauges by door 2R looked good. After about 3 hours into the flight; the Purser called stating that the left side of the aircraft lavatories and the forward upper deck had stopped working. We called Dispatch and Maintenance to try to diagnose the problem. We tried to reset the tank that was full but could not. We knew the biggest lavatory tank was full; but did not know for sure how long we could fly before the other tanks would eventually fill up. We made the conservative decision to land at an enroute airport before a bad situation got worse. We had to dump 62;500 pounds of fuel at FL320 so we would not land overweight. The approach and landing was normal and below maximum landing weight. The lavatories were serviced. The people that serviced the airplane said that the main tank was full; but the other three tanks were about 10% full. The indicators at 2R showed more than 10%; but were they accurate? I don't know. When the lavatory service was completed and the aircraft was fueled; we proceeded to RJAA. What went wrong that led to this problem? I don't know. On the surface; it looks like everything was done right. We received a completed service form. The relief pilots said the gauges looked good. What else could we have done? Was there a problem with the gauges? Was there a problem with the person dumping three tanks; not four?

Data retrieved from NASA's ASRS site as of April 2012 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.