1. A forward CG results in a nose-down fuselage attitude, which presents the horizontal stabiliser to the airflow at an inefficient angle, increasing its profile drag and aerodynamic load, producing an even greater downforce.

The helicopter trying to counteract the increased drag and the increased stabiliser's downforce, will demand more thrust and power, thus decreasing its range (total distance covered) and endurance (total airborne time).

If the CG is too far forward beyond the forward CG limit, there may be insufficient aft cyclic to hold the helicopter in a given position, particularly in the hover. It may be unable to flare, thereby increasing the landing distance and it may be impossible to achieve a level-skid landing, causing damage to the skids.

2. An aft CG will reduce drag, the stabiliser will be less loaded, thus the range and endurance will increase. However, with aft CG, the forward cyclic required for high speed thrust is more, increasing the bending moment on the rotor mast.

If the CG is too far aft beyond the aft CG limit, there may be insufficient forward cyclic to prevent the tail rotor and boom from striking the ground. Additionally, it will cause the helicopter to pitch nose up, so forward cyclic will need to be used to prevent rearward drift. As a result, the maximum forward speed is further limited and V_NE cannot be reached. Wind is also a factor, because blowback requires forward cyclic and this may already be at its forward limit.

Therefore, a CG outside of the allowed range, reduces the helicopter's performance.