That’s because the crew received low fuel level alerts. The checklist calls for opening the crossfeed valve once it is determined that no leak exists. The imbalance was the consequence of differences in fuel pump pressure outputs, which incidentally the sim cannot replicate.
The fuel imbalance started before the first fuel low light came on. Most likely as the crew had opened the crossfeed valve, possibly in an effort to ensure both engines had fuel if they forgot. This was discussed by the ATSB in the final report, and they had the conclusion the crew was actioning low fuel and balance operation from memory and not using the QRH. That being said they didn't see an issue with it because of the workload at the time, and the fact that Boeing does not consider large imbalances as an issue, just a wear and tear consideration. So as they stated at the end, the open crossfeed led to the No 2 tank having only 18 kg of fuel at shutdown, however with the crossfeed open both engines would have received fuel from the other tank had it run out. So the crossfeed being left open did lead to a large imbalance, but it was safe to do so, but was avoidable had they waited until a low fuel light actually came on.
Originally Posted by
non_state_actor
Yeah nice try🙄
This QF incident had multiple screwups of published procedures including a checklist. If they had either followed the fuel transfer from the manual or just did the checklist properly they would have been fine.
Not sure what the 'nice try' was about. The ATSB had a little swipe at the VA crew but then said they did nothing wrong, there is a whole page on the subject in the final report. I was showing that the ATSB pointed out the crew were actioning this checklist from memory without regard to the QRH, which is what led to the QF crew doing what they did. Any checklist that can result in a shutdown should be run carefully, unless time pressure is an issue, which it was not in QFs case. BTW the A330 evacuation at the terminal is another QF example of crew not actioning a checklist correctly for a failure, then there is at least the QLink Dash 8 brake fire incident as well. CASA probably should be asking QF group for a please explain on this sort of reoccurring non compliance. Do these companies keep the QRH down in the rear galley or somewhere hard to find? It seems not so quick reference if pilots are just memorizing it (poorly) and stuffing up.