What happened
A certified flight instructor was conducting primary flight training for a pre-solo student when the aircraft departed from Van Nuys Airport. The instructor proceeded to the Santa Clara River practice area. During an undetermined phase of flight over the dry river bed, the Robinson R22 (implied by context, though source only specifies helicopter) struck power lines that were suspended from poles located north and south of the river bed.
Following the impact with the wires, the helicopter descended approximately 40 feet before striking the ground on its right side. The student, occupying the right seat, sustained 1 fatal injury.
The investigation
An examination of the aircraft's engine assembly and airframe was conducted, which revealed no evidence of a mechanical malfunction occurring prior to the impact. Investigators did note wire mark striations on one of the main rotor blades.
Safety message
Following the accident, the flight school operator issued new instructions to employees regarding the specific locations where off-airport flight training is permitted. The area containing the accident site has been excluded from all authorized training areas.