Jason,Viper

Thanks for your advice.
Our plane is fiberglassed,the joints between
ruder,fuse and wing are tight,I after talk with my son, we are suspicious about the servos, they are JR8411 digital servos.
The interrogation is that it happens at full power.
I think that something related with incidences,or
gaps,had to be noticeable at 80% of power.
Will see tomorrow.
Have a nice weekend,
Pedro