Dear Christiaan,
rinsing implies to me a soft shower with water. During flight the rain does also not hit the case/sealing in 90° angle due to the position of the sensor on the fuselage.
So how about the sealing, if high water pressure is used from close distance? It might be possible then.
What I ask myself is, if the sensor doesn't have a heating? I found one here
http://www.goodrich.com/portal/goodr...%20Systems.pdf
from Goodrich, which has a standard case heating, but optional vane heating. Is it similar to the one used by Airbus 320?
Another question is: if the water is really inside the case, then it can hardly evaporate. Did the crew experience a nightmare, that could have occured any time later with passengers on board?
And for the sake of terminology: I guess the crew didn't see the maneuver as a "test flight", but as a demonstration/training flight and such didn't expect anything to go wrong. That is also highlighted in the BEA report.
So we have to ask, what would have happened if the AoA sensors have given correct values? Most probably nothing special would have happened and the crew still alive.
There is a good summary of the BEA final report on the aviationherald
http://avherald.com/h?article=410c9cec/0015&opt=0
regards twinotter