Due to the shape of the tanks Engine 2 will stop after approximately 23 minutes and then engine 1 after 27 minutes.
Apologies for my maths if wrong but having followed this thread, and its offshoots, I thought the average fuel burn could be as low as 180Kg to 220Kg per hour depending on Tq setting. I will use 200KG as a middle ground.
that means 3.33Kg per minute being burnt or 1.67KG per engine per minute. with a 4KG difference between the two tanks that would give you 2.4 Minutes. If you also factor in that once OEI the working donk will be at a higher Tq then the fuel burn will also increase reducing this time even further. So in fact if you think that you have 4 minutes to silence it may come as an even greater surprise when No. 2 stops within half that time!
There has also been a lot of questions on how two engines can be lost at the same time. Unless I have missed something we do not know that is what happened and
If fuel starvation for whatever reason was the cause then the above scenario of Two followed by one would be more likely.
If after No.2 stopping you run through the drills establish OEI check for other problems fire etc and then assess and address the problem you could find yourself working the overhead panel ultimately. Making the emergency shed bus then checking pump circuit breakers switch config. etc. If whilst doing this and left hand is holding flip cards or working above your head on panel when No.1 stops allowing for Pilot intervention time the Nr may well have been below recoverable before the lever was lowered. Even if only close to it the only way to increase Nr is to accelerate (not easy with not a lot of height below you) or load the disc (hard to flare when already probably at 60Knts or so OEI and still trying to asses the situation). This will leave you with a slow forward speed no Nr situation ending up with all on board as pax.
There is very little rotation at all once blades are fully stalled as anyone who has seen the video of the R22 falling completely level with only a couple of RRPM on till it impacted can tell you. The 135 is a low inertia system and if the lever is not lowered quickly or fully pulled up to early without any drive the system will effectively stop.
Just the rambling thoughts of an idiot who will now duck for cover.