This study aims at exploring the interest of using bifurcation theory to analyse concretely helicopter flight dynamics. A state-of-the-art allows to show how the methodology was applied with success in the case of fixed-wings aircrafts flight dynamics and presents some phenomenons highly nonlinear coming from the helicopter world. The first step is to set up the issue. Informatical works end up with the coupling of the HOST code of helicopter flight mechanics from EUROCOPTER and the ASDOBI code of dynamical systems analysis from ONERA. An analytical helicopter model absolutely dedicated and adapted to this application is also developed. Moreover, it is shown that the required mathematical formulation of the evoked problems is based on a differential algebraic system representation. In a second step, three illustrative cases of this approach are studied. Firstly, the aerodynamic instability due to the vortex rings formation at the rotor periphery in some flight cases is analysed and bifurcations of real eigenvalues are diagnosed. A new criterion to delimit the region of instability is given by the calculation of the locus of these bifurcations. Then, the case of the Dutch roll is examined showing that the underlying (supercritical) Hopf bifurcation turns out to give rise to stable limit cycles. Finally, the study is interested in aircraft-pilot coupling. Pilot induced oscillations are determined for the chosen command channel. Saddle-node bifurcations of limit cycles and jumps of periodical orbits corresponds to the handling qualities cliffs observed. ; Cette étude consiste à explorer les possibilités offertes par la théorie des bifurcations pour l'analyse concrète de la dynamique du vol des hélicoptères. Un état de l'art permet de montrer en quoi la méthodologie a fait ses preuves dans le cas de la mécanique du vol des avions et présente quelques phénomènes fortement non-linéaires issus du domaine des hélicoptères. Dans un premier temps, il s'agit de mettre en place la problématique. Des travaux informatiques ...