The first month-long phase of the two-phase test program involves physical tests to prototype #4. Electrical discharges are simulated from a structure enveloping the aircraft. Induced current passing through a critical components harness is measured to evaluate the effects of lightning strikes.
In phase two, test labs validate data gathered from the aircraft.
Lightning protection is required for certification by civil aviation authorities. A manufacturer must prove that there will be no catastrophic failure if the aircraft is struck by lightning.