DB,
All that is well and good....except for the fact that "fuel remaining at touchdown" is supposed to be in the Supply Tanks with Transfer Pumps "ON".
In this case....it wasn't and they were not.
How is it possible to miss the Transfer Pumps being "OFF", and the Supply Tanks showing depletion of contents?
Are there not Caution Lights showing the Pumps being off?
In that series of aircraft one has to monitor three tanks...not just total fuel.
When it comes to believing Warnings and Indications....especially with Fuel when at minimum fuel levels (even if determined only by time in flight)...the prudent Soul ALWAYS goes with the most dangerous of the two.....ALWAYS.
Evidence clearly shows the Crew KNEW there was a fuel contents issue.
They may not have known the true extent of the problem....and as you state....if Dave did know of the independence of the two systems he made a fatal error in judgement.
If he did not...that shows a problem in Training and Qualification that set him up for a bad decision.
That the Transfer Pumps WERE OFF....when everything says they should have been ON.....there is not getting around that fact.
Had those Pumps been switched on and just one of them worked....this accident would not have happened.
Why were they OFF....why had Dave not switched them back ON and why did he not see and react to Cautions they were OFF?
I flew the 105 and 117 series of aircraft that used the same general fuel system as the 135.....we never turned the Transfer Pumps OFF....never!
We also closely monitored the fuel contents in all Tanks especially late in the flight.