TR - I'd agree, the discussion of "High" & "Low" unuseable fuel is a red herring IHMO. Reports of "spluttering" & "sparks" add confusion to the mix for those large numbers of us who have managed to fly twin turbines for enough years not to have experienced either. I've flown to 60kgs in a 135 with no problems, save for close monitoring/re-calculating of the total quantity in the final few miles, out of nervousness that I had the longer range calculations wrong. Three amber captions already, with two red ones & their accompanying bongs completing the set just before, & just after, the skids touched the ground, perfect.
I digress - if the discussion centres on unusable fuel, the real question is why the recovered fuel may not have been getting to the engines, given that most of it should have been useable, certainly enough to get back to base & land safely anyway, even if significantly below MLA.
So long as the correct (depending on attitude), or both, transfer pump/s was/were switched on & working, there should have been adequate supply to both engines, whether the quantity readings were correct or not.
40odd - I'd agree completely, and wherever you choose to test fuel starvation, do it with both skids planted firmly on the ground!
As I've already said, whilst there may have been an unfortunate system failure or two, I can't believe all warnings were conincidentally inoperative as well, sadly.