Some time ago I'd attempted, unsuccessfully, to find the relationship of TAT to wing boundary layer temperature with a view to predicting fuel temperature trends.
Suddenly the latest, September 2008 Interim Report on the G-YMMM accident comes up with:
On long flights the temperature of the fuel in the main wing tanks will tend towards the temperature of the boundary layer around the wing, which can be up to 3°C lower than TAT
Expensive piece of research
