777 fuel leak

[787cruiser]

B777 fuel leak

I know a former colleague who had an actual engine fuel leak. As far as I can remember he stated that he was unable to ascertain whether it was a tank fuel leak or engine fuel leak. From the ECL and QRH non-normal checklist, he knew that the latter portion of it addressed an engine fuel leak but conditional on visual observation or the leak rate of more than 1000lbs per 30 minutes. As the leak rate was far less than 1000lbs per 30 minutes and there was no visible sighting ( night flight ), he was unable to definitely nail it as an engine fuel leak. Due to the frequent fluctuations in fuel totaliser quantities very common on the B777, even with inflight real time data transmissions of aircraft engine and fuel parameters to maintenance control, the maintenance and engineering personnel were convinced that it was a false alarm due to totaliser fluctuations and he was instructed to continue to destination by both the dispatch and maintenance controllers. As the difference in left and right wing tank burn off ( as per the checklist ) was only about an average of 200lbs-500lbs per 30 minutes and no visible sign of any fuel leak from engines and tanks, he was reluctant to conclude that it was an engine fuel leak, but he was fully convinced that there was a fuel leak somewhere. He countermanded company despatch and maintenance instructions and diverted to a suitable alternate but kept the engine on the suspected side at reduced thrust, with plans to fully shut it down once he get confirmation from airport safety inspection vehicles after landing. Due to ETOPS considerations and possible lightning activities he chose not to shut down or proceed to the nearest alternate. After landing, airport safety vehicle found a small fuel leak from one of the engines and he promptly shut it down right after touchdown. For all his efforts he was grounded and a " kind of punished " for countermanding company instructions. The company claimed in its findings that Boeing recommended following the QRH and ECL closely with the ambiguous remark that the checklist addresses and assumes engine fuel leak, not other fuel leaks. His contention that fuel leak was far less than the criterion of 1000lbs per 30 minutes was not addressed and so were the possibility of tank or manifold leaks were similarly dismissed. Similarly his contention that the checklist did not have a an indent to definitively define it as an engine checklist were rejected. So as we can see, Boeing checklists do have grey areas and pitfalls.