How Is Lift Force Calculated for a Helicopter?

[tennisacerg]

A 4600 kg helicopter accelerates upward at 2.0 m/s^2. What lift force is exerted by the air on the propellors?

I don't know how to do it.

Please help

 

[geoffjb]

A 4600 kg helicopter accelerates upward at 2.0 m/s^2. What lift force is exerted by the air on the propellors?

I don't know how to do it.

Please help

Draw a Free Body Diagram (with every force) and remember that $F=ma$ and $w=mg$.