Thank you waffler
Most illustrative
As for the AI procedure to try those wax crystals not to get into the fuel lines, maintenance Is telling me they are getting concerned with all these flights doing the OUTR TK XFR to INNR and thus leaving the tips bending for longer than they think they've been designed for.
Conclusion :
AI recommends to lower FL and Increase M# ( although there's a graphic in Getting To Grips with Cold WX Ops where it show the latter is a much more expensive option than the first one ) but, finally, as we reach our fuel type freezing point, recommends to XFR the problematic TKS into the inner ones.
I believe they must have the wing tips structural problem more than very well sorted out
Even if this happens daily, as it does in our company in northern winter.
I guess they would have sent a tech notice or something otherwise
The least we are now, is legally covered
Maint. Will confirm if we are technically too ...