  Preliminary results of study of $K^\pm\to3\pi^\pm$ decays by the NA48/2
experiment at CERN SPS are presented. They include a precise measurement of the
direct CP violating charge asymmetry of Dalitz plot linear slope parameters
$A_g=(g^+-g^-)/(g^++g^-)$, and a measurement of the Dalitz plot slope
parameters $(g,h,k)$ themselves. Due to the design of the experiment, and a
large data set collected, unprecedented precisions were achieved.
