  We propose a phenomenological three component model describing the decay
amplitude of the process $D_{s}^{+} \ra 3\pi$. The first component is a
constant background, the second one is a Breit-Wigner amplitude associated to a
quasi two-body $f_{0}(980) \pi^{+}$ state and the third one another
Breit-Wigner amplitude corresponding to a possible quasi two-body $\rho(770)
\pi$ state. We show that it is possible to reproduce the observed total rate
for $D_{s}^{+} \ra \pi^{+}\pi^{+}\pi^{-}$ as well as the two other measured
branching ratios for the non resonant part and the resonant $f_{0}\pi^{+}$ one.
Implication of the $\rho\pi^{+}$ state, of which an experimental limit has been
given, is discussed. An upper bound in the 10 MeV range for the decay constant
$f_{\pi'}$ of the $\pi(1300)$ meson is obtained .
  Predictions are given for the $D_{s}^{+} \ra \pi^{0}\pi^{0}\pi^{+}$ rate as
well as for the $\pi^{+}$ and $\pi^{-}$ ($\pi^{0}$ and $\pi^{+}$) energy
distributions for these two decay modes $D_{s}^{+} \ra \pi^{+}\pi^{+}\pi^{-}$
($D_{s}^{+} \ra \pi^{0}\pi^{0}\pi^{+}$) respectively.
