777 fuel leak

[787cruiser]

Hi Sink Rate,

Thank you for your well considered post. The fore-mentioned former colleague of mine indeed made these considerations during the incident. He deduced that there was indeed a fuel leak ( in spite of the fact that some B777 totaliser do behave wildly at times with fuel differences between calculated and sensed going as high as 6000lbs to 7000lbs ). However the leak rate was far below that ballpark figure of 1000lbs per 30 minutes, and there were no unusual fuel flow/fuel used indications. Even the maintenance control with real time engine data monitoring was fooled by the fluctuating totaliser readings, low leak rate and normal engine/fuel parameters. He realised that shutting down an engine during ETOPS operations would bring about more operational and safety issues especially that most of the available suitable airports and diversionary routes on that particular night had thunderstorm activities which could prove fatal in case of lightning strike should he still be leaking fuel in spite of engine shutdown. Like someone indicated, the engine could be restarted but during the time needed to positively ascertained that it was not an engine leak, the aircraft would have to be drifted down to cloud laden lower levels which he wanted to avoid. In his case it indeed turned out to be a small engine fuel leak; and the despatch and maintenance guys were all out to cover their embarassment. The safety guys were initially not happy that he did not follow Boeing procedures to shut down the engine...the safety dept was dominated by B744 guys who knew next to nothing about the intricacies of real life ETOPS operations.

As I had indicated earlier, the Boeing fuel leak checklist has pitfalls exactly as you alluded to...normal fuel balancing after the engine shutdown. I there is indeed a tank fuel leak and the engine shutdown without the crew being any wiser, it can be disastrous.

I was initially not aware of this fact, but that particular captain pointed out to me that he was well aware of the fact that the fuel leak checklist did cover other fuel leaks as well a engine fuel leak with the provision that visual confirmation being vital. The portion of the checklist dealing with engine fuel leak is generally misinterpreted by most crew memebers. He maintained that if there are procedural steps following a statement in the checklist, those procedural steps WILL HAVE AN INDENT immediately below that statement. This was something he tried enlightening the safety dept, but the B744 aces over there just laughed it off as a despaerate line pilot clutching at straws to prove his point! I learnt something old but highly forgotten.