Define the aircraft requirements and mission profile
Study rotorcraft aerodynamics, structures, controls, and systems
Obtain all required certifications, permits, and engineering approvals
Design the airframe, rotor system, drivetrain, landing gear, and control systems
Perform detailed engineering analysis and simulations
Select suitable materials and components
Fabricate the fuselage, mast, rotor blades, transmission, and control linkages
Assemble the main rotor, tail rotor, engine or motor, and fuel or power system
Install avionics, instrumentation, electrical systems, and safety equipment
Balance and align all rotating components
Conduct ground testing of controls, powerplant, and vibration levels
Perform static load and structural tests
Carry out flight testing under qualified supervision
Inspect, refine, and retest until the aircraft meets safety standards
Maintain the helicopter with regular inspections and scheduled servicing