• I. Moving the engines from the wing to the fuselage improves wing flutter suppression. INCORRECT.

Flutter of control surfaces is a divergent oscillatory motion of a control surface caused by its natural frequency, the interaction of aerodynamic forces, inertia forces and the stiffness of the structure. To prevent flutter, stiffness should be increased and/or the CG of the control surface should be moved forward of the control hinge (in front of the torsion axis), this can be achieved by adding a balancing mass in front of the control surface hinge line (the more forward the CG of a control surface is, the more stable it will be). Engines mounted on the wing will move the axis closer to the aerodynamic centre of the wing. As a result, changes in lift will have a smaller torsion moment, thereby decreasing the chances of flutter.

II. Excessive free play or backlash reduces the speed at which control surface flutter occurs. CORRECT.

Excessive free play essentially means that the control surface can start oscillating without moving the control column. Since there is little resistance from the control mechanism to prevent the surface from moving to one direction to the other, flutter will occur at a reduced speed.