WHBM
"How can the engine design have been in service for 15 years before such incidents happened. What caused it to work fine on comparable flights until now?"
As the AAIB report states, for the BA038 flight the minimum fuel temperature was in the bottom 0.2% of recorded temperatures. So if the system has a problem it may have taken this long for it to show up. It seems that the Delta flight came also from China but I haven't seen a temperature profile to be able to tell if it sits in the same family. Has it been an excessively cold period over these routes?
AIRFOILMOD
"The Problem isn't Ice, it's water. "In Spec." Fuel has it and at very low temps it takes shape as granular microscopic particles. As such, it does no harm. At Cruise, in VERY low temp. over many hours, the ice melts and refreezes in the FOHE.
There is no evidence that the the the freezing took place at the FOHE. I think think most now agree that ice formed upstream and was released in a relatively large quantity to the engine. The FOHE is then a likely place for the ice to stick. As the reports state testing has shown that the FOHE will block with sufficient quantities of ice.
It may therefore be prudent to improve the FOHE's handling of large quantities of ice, if Boeing cannot prevent this from occurring, but will it be enough to prevent further events? As for who should be liable for the mod and subsequent rollover. In these events it seems the engine is being supplied with fuel containing a quantity of ice it wasn't certified to live with. This would suggest an aircraft issue but I suspect RR/Boeing will jointly foot the bill.
Last edited by spilko; 14th March 2009 at 09:38.