Primary finding
Probable cause
The failure of the pilot to reduce the engine power control levers to ground idle prior to leaving the helicopter, resulting in the unmanned helicopter moving on the helipad and performing a dynamic rollover.
Investigator assessment
Analysis narrative
The pilot got out of the helicopter with the engines running and the rotors turning to check on the security of a cabin door, and the unmanned helicopter began moving on the helipad and rolled over. The pilot had completed a nightime, helicopter, air taxi flight, and was preparing to depart the elevated helipad to reposition the helicopter to the operator's base. After deplaning his passengers the pilot returned to the cockpit and was preparing to depart when he noticed a door unsecured indication on the instrument panel for the left cabin door. The passengers had deplaned through the right-hand door and the left door annunciation had not been on during the inbound flight. He thought one of the passengers might have released the left door latch inadvertently while preparing to deplane. He idled the engines and exited the cockpit to check the door. He reclosed the door and returned to the cockpit; however, the door open annunciation came on again. He recalled leaving the cockpit "2 or 3 times" to deal with the door and said he was "frustrated with it." He did not recall retarding the engine power control levers to ground idle before leaving the cockpit the final time. While out of the cockpit, the wheel-equipped helicopter started to move as the pilot was returning to the cockpit. He recalled it was moving toward the edge of the helipad. He returned to the cockpit; however, before he could regain control there was a confusing sequence of events and the next thing he knew the helicopter was on its side. The pilot reported there were no mechanical discrepancies with the helicopter up to the time of the event. He remarked that it was very light [weight] with no one else on board. On the deck of the helipad there was a tire skid pattern consistent with a dynamic rollover event. The engine power control levers were found in the "fly" position.
Source record
Factual narrative
HISTORY OF FLIGHT On July 21, 2001, at 0049 hours Pacific daylight time, a Sikorsky S-76A, N769BB, yawed to the left and rolled onto its right side while standing unmanned with both engines operating and rotors turning at the University of California, Los Angeles (UCLA), Medical Center helipad in Los Angeles, California. The certificated airline transport pilot, the sole occupant, received minor injuries and the helicopter was substantially damaged. The repositioning flight was operated by Helinet Aviation, Inc., under 14 CFR Part 91, and was departing for Van Nuys, California. The flight was operating on a company VFR flight plan. Night visual meteorological conditions prevailed. The pilot was interviewed in the hospital emergency room about 3 hours after the accident. He reported he flew an organ harvesting (medical) team to Fresno and returned them to UCLA immediately before the accident, arriving just after midnight. On the inbound landing he approached the helipad from the southeast and made a hovering pedal turn to a westerly heading, landing in the center of the helipad. He recalled he set the parking brake before landing. He deplaned his five passengers through the right-hand door with the engines operating and the main rotor in motion. He had previously briefed the passengers for the standard (company) procedure to be used to deplane with the engines operating. After his passengers had gone inside the hospital, he returned to the cockpit and was preparing to depart when he noticed a door unsecured indication on the instrument panel for the left cabin door. The passengers had deplaned through the right-hand door and the left door annunciation had not been on during the inbound flight. He thought one of the passengers might have released the left door latch inadvertently while preparing to deplane. He idled the engines and exited the cockpit to check the door. He reclosed the door and returned to the cockpit; however, the door open annunciation came on again. He recalled leaving the cockpit "2 or 3 times" to deal with the door and said he was "frustrated with it." He did not recall retarding the engine power control levers to ground idle before leaving the cockpit the final time. While out of the cockpit, the wheel-equipped helicopter started to move as he was returning to the cockpit. He recalled it was moving toward the edge of the helipad. He returned to the cockpit; however, before "belting in" and before he could regain control, there was a confusing sequence of events and the next thing he knew the helicopter was on its side. After the events ceased, he recalled he was loose inside the cockpit and was not restrained by his seat belts. He was disoriented in the darkness and had trouble finding the fuel shutoff levers, and didn't know how he got out of the helicopter. He recalled trying to kick out the windshield and being concerned that the helicopter would either catch fire or roll off the [elevated] helipad. The pilot reported there were no mechanical discrepancies with the helicopter up to the time of the event. He remarked that it was very light [weight] with no one else on board. In his written report, in the block titled "Person At Controls At Time Of Accident" the pilot checked "No One," and in the boxes titled "Seat Belt Used" and "Shoulder Harness Used" he checked "No." A medical center employee witnessed the accident from the seventh floor of the hospital about 350-feet distant. He reported: . . . "During many years of working here I observed takeoffs and landings often. I am familiar with the sounds that accompany increased rpm's during a maintained "throttle up" just before takeoff. On that night I heard a total of three throttle ups. During the first two I was working at my desk. The times are approximations but the first lasted 30 seconds and was followed by a throttle down. After 2 or 3 minutes there was another throttle up lasting 30-60 seconds, again followed by a throttle down. Two minutes later there was the third throttle up. This was a unique sequence of events to me so I left my desk and walked a short distance to the window to observe. I observed for 1 minute during the third throttle up. A person was outside the aircraft, moving quickly. He opened and closed a small door to the rear of the craft and moved about diligently. The distance and ambient lighting conditions prevented me from seeing exactly all activity outside the aircraft. I briefly lost sight of the pilot due to these conditions. At this time the helicopter made a 1/4 turn in a counterclockwise direction across the helipad. It then quickly turned on its right side and the main propeller [disintegrated]. During the 1/4 turn it was easy [to] observe the pilot clinging to the [outside] of the helicopter close to the front door. It was difficult to tell if the door was open or closed but I remember seeing all four of the pilot's extremities. He wore a dark jumpsuit. There was a flash from the point where the propeller meets the main body of the helicopter on top. I left the window from fear of flying propeller debris and a possible explosion. When I returned [approximately] 5 seconds later the pilot was walking around the nose of the helicopter towards the hospital doorway . . ." PERSONNEL INFORMATION During his interview, the pilot stated he had flown off this heliport at night numerous times. He said he was not fatigued. He rested well Thursday night and awoke at 0830 or 0900 on Friday morning. He reported for work about 1330. According to duty time records provided by the operator (attached), the pilot had worked each of the 8 preceding days. His duty time was between 8 and 13 hours each day. His total flight time for the 8-day period was 14.6 hours. The pilot reported for duty on Friday, July 20, 2001, at 1330, after a 17.5-hour rest period. WRECKAGE AND IMPACT INFORMATION The accident site was on the private heliport immediately adjacent to the UCLA Medical Center, which is on the UCLA main campus in the Westwood district of the city of Los Angeles, California. The heliport was on the roof of a 3-story structure and was marked to accommodate a single helicopter. In the center of the helipad was a red square about 30-feet on each side, and within the red square was a white "cross" symbol. Within the white "cross" symbol was a single red "H" symbol with the "up" direction oriented east or west. While standing at the center of the "H" symbol, facing west toward the fuselage, the Safety Board investigator noted, about 4 feet to his left, a dark black spot on the surface of the helipad resembling a tire pivot location. To his right an equal distance was an arcing, gray/black, skid mark resembling the tire tread pattern of the helicopter. The distance on the surface of the helipad from the pivot mark to the arcing skid mark was equal to the tread distance of the helicopter main landing gear. The arc extended through about 90 degrees from the investigator's right, counterclockwise, and ended in front of him and slightly to his left. Near the end of the arc (in front of the investigator), the outboard edge of the arc exhibited a darker black shoulder. Near the end of the arc and about a 60-degree angle to the arc, was a second, dark black, linear skid mark resembling that made by a tire being dragged sidewise across the deck. The dark black skid mark was about 3 inches wide and 6 feet long, irregular in density, and ended near the right main landing gear wheel of the overturned helicopter. The fuselage of the helicopter was lying on its right side (about 110 degrees right roll angle) at the western perimeter of the red square area with the nose pointed south and the underside of the fuselage to the east. The landing gear was extended. On the underside of the tail stinger was a pattern of red paint scrape marks extending from right-rear to left-front.