What is the significance of the empty weight in helicopter weight and balance calculations?

The empty weight is a crucial starting point for weight and balance calculations because it represents the weight of the helicopter as it is equipped to fly before adding any crew, passengers, fuel, or cargo. Knowing the empty weight accurately is essential for determining the useful load, which is the maximum weight that can be added to the helicopter without exceeding its maximum gross weight. The useful load is calculated by subtracting the empty weight from the maximum gross weight. The empty weight also includes the weight and location of permanently installed equipment, which directly affects the helicopter's center of gravity (CG). The CG must be within specified limits for safe flight. An inaccurate empty weight will lead to incorrect calculations of the useful load and CG, potentially resulting in an overloaded helicopter or a CG outside of acceptable limits, both of which can severely compromise the helicopter's stability and control.