  Theoretically a possibility of covariance violation in weak decays is not
ruled out from the first principles, while there are some models predicting
non-covariance revealed in weak interactions. The experimental evidence for
isotropy violation in $\beta$-decays was recently reported. We present a study
of the dependence of electron flow rate and $\beta$-electron energy in the
decay of $Sr^{90}$ with respect to the direction of electron emission. An upper
limit of $1.4 \cdot 10^{-5}$ on directional dependence of $\beta$-electron
energy was obtained.
