A B747-400 diverted to an alternate for an engine fire warning fault. The international departure was delayed for fueling; weight and customer service issues. The crew waived contractual crew rest requirements in order to get the flight out; but became extremely fatigued during the diversion.

Narrative

This report concerns issues of crew fatigue; a fueling error; and subsequent confused handling by miscellaneous employees. We arrived at the aircraft for our ZZZ flight aware of a deferred B fire loop on engine #3; but learned from Maintenance that the A fire loop was also inoperative; making it illegal for us to depart. The repair of the A loop; which they finally determined would have to be spliced; took about 2 hours. The Maintenance Lead did a great job of communicating frequently with us; and was conscious of the potential for crew illegality. I believe the Maintenance Crew was working as quickly as they could to determine the problem and fix the A loop. But in that time; with a full load of passengers on board and the APU running; we burned into our release fuel; and with the concurrence of Dispatch we decided to add 2;000 LBS. Somehow; however; we were overfueled; bringing our weight to 879;100 LBS. Maximum taxi weight on the B747 is 878;000 LBS. Several of our employees; I believe they were Load Planning Supervisors; came aboard and tried to help resolve the issue. They discouraged refueling; saying the next step would be to remove non revenue passengers; followed by; if necessary; removing freight. In the meantime; the Captain was in communication with Dispatch via SATCOM and was trying; among other things; to confirm the final zero fuel weight; which had changed several times. There was a great deal of confusion over the zero fuel weight issue and whether the aircraft might be legal to push back without removing passengers. This was complicated by the fact that the load planners had apparently already gone home for the night. An inordinate amount of time elapsed with everyone on the phone to everyone before it was finally decided that removing 6 non revenue passengers would be the solution. Unfortunately; this decision was made; despite our warnings ahead of time; 6 minutes before the cockpit crew was to go contractually illegal. The removal of the non revenue passengers was accomplished as quickly as possible; but we still went slightly past our duty time limitation; which at that point we agreed to waive in the interest of getting the flight out. After we pushed from the gate we still needed an additional 25 minutes on the ground with all engines and the APU running to burn the fuel down to MGTOW of 875;000. We finally took off over 3 hours late. Several hours into the flight there were indications that the A loop was failing; the specifics of which I cannot relay since I was in the bunk. Both bunkies were awakened and informed that we were diverting to ZZZ as a precaution since it was doubtful we had proper fire sensing on the #3 engine. After dumping the required fuel; we had an uneventful approach and landing to ZZZ. With regards to crew fatigue: Any late night departure is already potentially at risk of crew fatigue issues merely due to human factors. Despite conscientious preparation beforehand; taking naps; getting up later than usual on the date of departure; etc; a crew might not always be fully rested for a late night departure. Adding delays increases this fatigue issue. Any delay is complicated; necessitating keeping everyone in the loop; communicating with Maintenance; Dispatch; passengers; Passenger Service Representatives; Flight Attendants. The Captain is very busy the entire time; as is the crew; as work is delegated and constant decisions are being made. Our decision to waive our legality; even though by only a few minutes; was one we had second thoughts about. By the time the A loop issue recurred inflight; the Captain and flying First Officer had been awake and on duty for a long time; and the bunkies had not had much rest. Thankfully the weather in ZZZ was good; and there were no issues to complicate our arrival. But what if there had been an emergency; or there was weather? The crew was; at that point; not at their best. I believe we need to honor the limitations of our contract; which is thereto protect not just us; but our passengers and our aircraft. The mentality of pilots is to succeed in their mission; to make things work. Our mindset is such that to walk off the airplane after trying so hard to resolve problems and get the flight underway is difficult. There needs to be much greater awareness and support on the parts of Dispatch; Maintenance; Passenger Service Representatives; and load planners on crew limitations and a clear understanding of what time the flight will no longer be legal to depart. Awareness; forethought and ultimately adherence in this area are crucial. As far as the fueling error; I cannot say how it occurred; but it was the straw that broke the camel's back in this instance; the thing that put us into an awkward creeping delay that ultimately led to a crew illegality situation and enhanced the issue of crew fatigue. With regards to the poor handling of the flight; I believe it took far too long to decide to remove the 6 non revenue passengers. I don't know what the delay was between Dispatch and everyone else involved in making that decision; but it could have been handled quickly and professionally and we could have departed at least 1 hour earlier. In this instance; there was no emergency; no loss of life or aircraft. But crew fatigue is a serious issue and one that needs to be given respect.