In the present work, the model of a tilted hexarotor with an attached 3 DOF manipulator is derived and three different wrench observer concepts originally proposed for Unmanned Aerial Vehicles are extended for the entire aerial manipulator. The system model as well as the observers are simulated in order to compare the performance of the different observer approaches under various conditions. An Extended Kalman Filter proves to fulfill best the most relevant requirements, i.e. the estimation accuracy and the robustness against measurement noise. Especially the noise reduction of the Extended Kalman Filter is far superior to momentum-based and hybrid observer for the proposed system.