Someone above published a survey undertaken by Grumman. It confirmed what I (and some others) have been saying from the start - namely that the formulations of jet fuels vary hugely depending on crude source, production process (eg hydrotreated, severly hydrotreated etc) additives used etc etc etc. The above list does all meet spec by the way. But for commercial privilege, I could publish a list of a few thousand jet samples, several hundred or so of which are off spec for a variety of parameters (but the high proportion of off spec results is not surprising given that I investigate Jet contaminations for a living)
The reported freezepoint for the subject fuel falls within the limited sample range (19 samples?) in the Grumman list - it was
ABSOLTUELY TYPICAL of the value you'd expect to see. If low freeze points were a problem, Defstan/ASTM specs would specify a range of acceptable freeze points not just a maximum. So please, do not continually harp on that at the FP was lower than it should be - it was not.
Few other pointers from preceding few posts:
Vapour pressure: This depends very much on fuel temperature. The lower the fuel temp, the lower the vapour pressure. If the fuel had an abnormally high vapour pressure the problem would have arisen during highest fuel flow rate and highest fuel temperatures - which would have been at takeoff. In any event, if the vapour pressure was too high, it would have been off spec on flashpoint (which it apparently wasn't)
Cal val: If cal val of the fuel was insufficient to provide sufficient thrust to arrest descent, how the heck could the a/c take off in the 1st place? In any event, Specific Energy forms part of the spec, and there is no indication that this parameter was off spec.
Additives: The allowed additive list for Jet A-1 is very restrictive, and additives used must be stated on QC's. If excess or unauthorised addives were used, it would have been picked up on GCMS.
Another point: Various people have talked about stratification. If the fuel had stratified, and the "good" components been consumed during the cruise leaving only "bad" stuff (technical terms
)- this would have been plainly evident to the AAIB by simple comparison of the measured quality parameters of the remaining fuel with the reported quality parameters of the supplied fuel. There is no suggestion in the AAIB reports that fuel quality differed significantly than certified at loadport.
Edited to improve the English (originally typed upon return from the pub
)