On November 22, 1994, at 1330 Hawaii standard time, a Robinson R22B helicopter, N31MK, collided with the ground at the Honolulu International Airport, Honolulu, Hawaii, while performing a practice autorotation. The aircraft was owned and operated by Rainbow Pacific Helicopters, Ltd., of Honolulu, Hawaii, and was engaged in a private pilot practical flight test with a designated examiner on board. Visual meteorological conditions prevailed at the time and no flight plan was filed. The aircraft incurred substantial damage. The private pilot applicant and the examiner sustained minor injuries. The flight originated at the Honolulu International Airport on the day of the accident at 1230 as a local area flight. According to a written statement from the examiner, the applicant completed the first part of the practical test satisfactorily. The last maneuver to be performed was a recovery from a 180-degree autorotation. The applicant entered the maneuver satisfactorily; however, at the bottom had allowed the main rotor rpm to decay and began to add collective input without adequate throttle input. The examiner said he took control of the helicopter, but could not regain main rotor rpm prior to ground impact.