Originally Posted by airfoilmod
Keep in mind
The Fuel flow is 6,000 pph at Idle, and the Fuel is very cold.
Just to get the facts straight. Idle fuel flow is less than 1,000pph (see first AAIB interim report, p.4, second paragraph), at which flow rate the difference between counter- and concurrent flow designs may become significant.
In the case of BA flight 38 the engines rolled back to between 5,000 and 6,000pph, which was still not as much as demanded, but significantly more than idle.
It is also worth noting that that reduced fuel flow was not low enough to allow the ice to melt sufficiently quickly (or at all), whereas all tests indicated that idle fuel flow was low enough.
Two more things to consider:
- would 6,000pph in a
parallel flow design have been low enough to allow the hot oil at the cold fuel inlet to melt the ice?
- would a
parallel flow design FCOC of the given size have enough oil cooling capacity at idle fuel flow?
I cannot answer either of these questions, but I assume RR engineers are already looking at them (and a lot more.)
Bernd