Jason has the answer. Have a look at his website,

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Assembly of the wood blades was very easy, and the manual showed clearly to first cut out the covering under the plastic blade root, glue the roots to the blades and screw fix them. These blades were 525mm length and they were kind of short for a 46 class helicopter. The blades were symmetrical but I felt they were too soft for real use. I use them nevertheless cause I could not found other 525mm blades in the market. After I assembled the blades I checked their balance and found that one of them was way off. I took some time to balance them.
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The wooden blades which comes with this helicopter always worked fine, so those FRB 525mm carbon blades should just be the right choice :-) However, I'll take a look for bigger blades if they fit well and post it in this thread.

Thanks all for the info!