Markieboy
I still don't believe an ETOPS airliner can have BOTH engines display the same behaviour at the SAME time due to fuel freezing or boost pump contamination.
It wasn't at the same time, it was seven or so seconds different. And that in itself was the most powerful piece of information that said it was a common cause but not necessarily an instantaneous common mode fault like (for example) an electrical bus, relay, or fuel pump failure.
Obviously you are a statistician. I'm a fuel guy and I have a different opinion, which is that identically built engines constructed to incredibly close and repeatable tolerances operating on identical fuel in an identical environment might well be expected to suffer identical failures at more or less the identical time.
There is another thread running on PPrune concerning the amber thrust reverser deployed caution lights that came on after V1 on the take off roll at Johannesburg recently for both inboard engines on a 744. There is a hell of a lot more potential variability in those circumstances over a shorter period of time but not only was there a common cause, the lights came on within a few seconds of each other.
As Nicolas Cage said in City of Angels "just because you don't believe it doesn't mean it isn't true"
Dairyground
You have kind of answered your own criticism by explaining the difficulties that the AAIB are having replicating the incident. But introducing artefacts like cameras into a fuel icing trial is just another example of us not learning from experience: even if you could do it, you change the dynamics of the fuel system such that it is not representative of the actual conditions.
Examples:
- When the original jet engines were tested using frozen chickens fired into the rotating turbine it was wrongly assumed that the test more or less replicated what would would happen when an engine encountered a bird at altitude.
- One reason the Kegworth 737 - 400 crash happened was because CFM extrapolated the data from the -B1 engine series to the -C1 engine on the -400. And we now know that the engine didn't behave exactly as predicated by the computer model or the ground run that used a modified spinner.
- When RR did the containment tests on a trent they may have modelled a blade separation, but they were still required to write off an engine by doing a real-time engine test where the blade was actually ingested.
I wasn't advocating mandatory in vivo testing of every powerplant with every fuel: I know that in vivo tesing is expensive. I simply want to see a dedicated low temperature research facility which has the laboratory testing you cite but which then has it confirmed by the in vivo testing of actual powerplants on a variety of fuels in a variety of environments. My understand that Boeing and the USAF have been doing it for years for miliatary applications.