According to the query of Renren Library, the main reasons why the helicopter main propeller does not use the thinner part of the trailing edge to cut the airflow are as follows:

1, Aerodynamic performance: Aerodynamic performance is considered in the design of helicopter main propeller. The thin cutting airflow at the trailing edge will change the aerodynamic performance of blades and affect the balance and stability of the aircraft.

2. Structural strength: The cutting airflow in the thinner part of the trailing edge weakens the structural strength of the blade and reduces the durability of the propeller, thus affecting its service life.

3. Vibration and noise: For the design of helicopter main propeller, reducing the blade thickness will lead to increased vibration and noise, which will affect the ride comfort and the pilot's operating experience.

In order to ensure the safety, stability and performance of the helicopter main propeller, it is a reasonable design choice to avoid cutting the airflow in the thin part of the trailing edge.