What if the Gauges were wrong Lead Balloon? They believed that had more fuel than they really had and didn't realise they were wrong till the noise stopped, would also explain why they'd be tempted to push on even with low fuel lows as apparently they did. Silly idea mind you as the Low Fuel Lights should have been good reason to stop and really check it out first but there's any number of organisational or environmental pressures that could lead them to pushing on and hoping the Gauges were right but the Low Fuel Lights were wrong? What if there was a butt load of water onboard for some reason? Fuel Exhaustion is a lack of usable fuel, not dry tanks, there could have been a significant amount of water in there somehow that caused whatever was in the tanks to no longer be "Usable Fuel". How about some sort of fuel leak that was fairly minor but not spotted meant they expected to land with min fuel but ended up not, or maybe the engines were burning way more than expected in conjunction with some fault gauges? There's a heap of possibilities and most of them would require the tanks to be drained and likely run through with fuel allowing them to take off with a known quantity of fuel to make the very short hop to Broome quite safely if they were only 39km away. Most of these should have been covered by good paperwork that would tell them the fuel figures didn't add up right to what the Gauges said but once again, plenty of Human Factor reasons that could explain them either ignoring the paperwork or having done a crap job of it, perhaps someone else along the chain involved gave them incorrect figures somewhere?
I'm curious to know exactly what effect water mixed in with the fuel would do to efficiency of the engines if not adequately picked up, someone has already said that it would contribute to fuel gauges overreading which is another possibility. Was it a case of some crappy Low Fuel Lights that "Always come on for no reason" that caused them to push on as well, wouldn't be the first crew to look at a major warning sign and say "Eh, don't worry, it always does that!" and continue on.
Bend Alot, Broome has a Satellite CASA office which I remember once upon a time was manned 2 weeks out of 4 (Quick google around shows an article from CASA even talking about it a couple of years ago but I don't know if that's still the case) and according to the CASA website Broome falls into the Western District which is covered by Perth as well:
https://www.casa.gov.au/standard-pag...ns-and-regions
https://www.casa.gov.au/standard-pag...ian-skies-safe
Once again, you're assuming that all CASA minions are out the door at 4.21pm, you have absolutely no way to know that. Which policy of CASAs is it that says "An SFP shalt take no less than 5 days to be issued..."? There isn't a Policy that dictates exactly how long an SFP takes, it depends on workload and when it gets there, doesn't mean one can't be processed in a short period when required or deemed a priority. You have no way to know at all whether an SFP was issued or not, you have no way to know at all if a LAME attended and signed off the MR before that flight, you have no way to tell what communications were made between Maintenance Personnel, CASA and the Operator. You're assuming all CASA personnel were gone by 4.21pm, you're assuming no Engineer went out there because no where does it implicitly tell you one did, you're assuming an SFP cannot be fast tracked because you've never had one fast tracked, you're assuming the defect was something not covered in the Manual and couldn't be signed off by a LAME and basically you're assuming all this because you can't imagine a possibility where your narrative is wrong so therefore all these assumptions must be correct.
Personally, I'm done with this conversation until more actual facts come out from the ATSB or someone with concrete first hand knowledge can fill us in.