A popping sound then a loud noise and a puff of smoke preceded the helicopter's fall to the ground, stated a 12 year old boy who said he saw the accident. Examination of the helicopter failed to disclose any trace of fire. However one main rotor blade contacted the left front of the cockpit and wrapped around under the helicopter. The wreckage was scattered over an area 300 x 700 ft. The passenger had about 65 hours of flight but no certificate and no known helicopter time. The PIC had previously had his commercial ASEL certificate revoked for giving flight instruction in a small airplane without having a CFI rating. The PIC had reapplied for and had been reissued his commercial certificate. He had since upgraded his certificate to an ATP for AMEL, commercial for ASEL, ASES, AMES and helicopter. He also had a CFI rating for ASMEL but not for helicopter. His flight experience could not be accurately determined because of conflicting data in airman records and pilot logs.