Ex FSO GRIFFO
Turned out a pest had made a nest in upper regions of the main tank vent, not allowing pressure inside/outside the tank to equalise and very difficult to discover during a daily. The EDP didn't have enough power to deliver fuel alone after 1+ hour flight....... my thoughts now lie with what happened to the bladder inside the tank?? probably got a bit smaller
patienceboy
The thought of rotate failure or efato did pester me for a while.
But had flown this a/c several times before, knowning it will +roc on 1 engine for a modest DA, we weren't mtow, had no take-off clearance issues and it was the RH engine..... and most of all the engine was still developing full power with the aux pump off, albiet at a lower pressure (the IO470 req's a min 20g/ph at t/o setting to remain "happy and cool"... which we would have been a little under if the aux pump failed but still would have had both engines one with a higher CHT)