NYC00FA127

the pilot's misjudgment of his closure rate, while turning to land on the rooftop helipad, which resulted in a collision with the building. Factors in the accident were the tailwind and the stuck windsock.

The pilot stated he approached the lighted rooftop helipad from the southwest, at night, with light winds. The helipad and hangar were just ahead of him, and he initiated a right pedal turn to align the helicopter towards the south. He heard a loud bang, and the helicopter rotated uncontrollably, nose right. He lowered the collective, and the helicopter struck the landing area. Examination revealed the tail rotor blade ends were fragmented, and marks on the top corner of the hangar were similar to a tail rotor blade strike. Due to other helicopters parked on the ramp, the only approach was from the southwest. Winds were estimated to be from 220 degrees at 10 knots with gusts to 15 knots. Examination of the hydraulic pump and hydraulic tail rotor actuator found no evidence of failure or malfunction. Personnel reported the windsock would occasionally get caught on its support structure, and not indicate the true nature of the wind. There was no other wind information available to the pilot.

HISTORY OF FLIGHT On May 6, 2000, at 2335 Eastern Daylight Time, a Eurcopter BK-117-A4, N911NC, operated by Petroleum Helicopters, Inc. (PHI), was substantially damaged while landing at the rooftop heliport at University Hospital (8OH9), Cincinnati, Ohio. The certificated airline transport pilot received serious injuries. Visual meteorological conditions prevailed for the medivac positioning flight that originated from Lunken Airport (LUK), Cincinnati, Ohio. The flight was operating on a company visual flight rules (VFR) flight plan under 14 CFR Part 91. The pilot was completing his sixth flight of the night. He had earlier made two landings at a nearby hospital, and had left the medical flight crew there after the second landing. He then flew to LUK to refuel, and was returning the helicopter to 8OH9 when the accident occurred. The pilot reported there were two other helicopters already on the heliport when he initiated his approach from the southwest. He observed the windsock hanging limp, not changing direction, and indicating a light wind from the southwest. He planned to make a nose-right pedal turn over the touchdown area, and point the helicopter to the south upon touchdown. The pilot further reported that the helicopter crossed the edge of the landing area and was almost to a hover when he heard a "loud noise or bang" from the rear of the helicopter. Simultaneously with the noise, the left rudder pedal pushed rearward, and the nose started to move to the right. The pilot reported that he recognized this as a loss of tail rotor thrust and immediately closed the throttles/power levers. He could see the concrete surface of the landing area through the windshield and knew he was going to hit the landing area. In the Pilot/Operator Report it stated, "While on final approach on an approximate heading of 070 [degrees], and just as the pilot was initiating a right pedal turn to align the aircraft towards the South, he reported hearing a loud bang followed by a hard pedal push." The helicopter struck the ground, and came to rest with the engines still running. The pilot then shut down both engines and closed the firewall shutoffs for the fuel lines. The main rotor was still turning, and he applied the rotor brake to stop it. The pilot was then assisted out of the helicopter, and taken to the emergency room for treatment. A witness in the emergency room who was flight following the helicopter, reported that she observed its approach on a closed circuit monitor. She saw the glow of the helicopter's landing lights, then looked away for a few seconds. When she looked at the monitor again, the helicopter was at the top of the monitor screen, and rotating nose-right, faster than normal. While rotating, it was also oscillating along its longitudinal axis. She saw the helicopter fall to the landing area and come to rest. The pilot door opened and she could see the pilot inside the cockpit. She tried to call him on the radio, but did not receive an answer. An off duty pilot was in the pilot lounge, one level above the landing area. He felt the building shake, and went outside to see what had happened. He could hear the helicopter's engines running, and looked around the corner of the hangar. He saw the pilot slumped over in his seat with the main rotor turning. After a few seconds, the pilot looked up, shut down the engines, and then applied the rotor brake to stop the main rotor. Additional people then came to the rooftop heliport, and they assisted in the removal of the pilot from the helicopter. The accident occurred during the hours of darkness, at 39 degrees, 8 minutes, 14 seconds north latitude, and 84 degrees, 30 minutes, 9 seconds west longitude. OTHER DAMAGE The southwest corner of the hangar roof was damaged. PERSONNEL INFORMATION The pilot held an airline transport pilot certificate for rotorcraft - helicopters, with a VFR type rating in the Bell 47. In addition, he held a commercial pilot certificate for rotorcraft - helicopter, and instrument helicopter. He was last issued a Federal Aviation Administration (FAA), second class airman medical certificate, on March 20, 2000 with a limitation to wear corrective lenses. The pilot had been employed by PHI for several years, operating in the Gulf of Mexico, and performing daytime rooftop landings on offshore oil platforms. He requested and was reassigned to Cincinnati, his first emergency medical services (EMS) assignment. According to company records, the pilot had received his initial BK-117 training from PHI, and passed his checkride on August 2, 1999. He passed another checkride on December 20, 1999. No problems were noted on his training form or checkrides. According to PHI, the pilot's total flight experience was 10,379 hours, with 189 hours of night flight experience. His total flight experience in the BK-117 was 91 hours. In the preceding 90 days, he had flown 30 hours, which included 8.5 hours of night flight experience, and 44 night landings. AIRCRAFT INFORMATION The helicopter was configured for medical work. The flight controls for the left front seat had been removed. In addition, there was a side-facing bench seat, and space for a stretcher. The pilot reported that, at the time of the accident, the fuel load was about 985 pounds. METEOROLOGICAL INFORMATION Following is a list of the winds from surrounding airports with their distance and bearing from 8OH9. Airport Time Distance Bearing Winds LUK 2353 4.4 NM 121 Calm CVG 2351 9.2 NM 238 Calm The closest weather-reporting site to the accident site was LUK. At 2253, and again at 2353, LUK reported visibility's of 1/4 mile and fog. The off duty pilot who assisted the accident pilot out of the helicopter reported the weather conditions on the landing pad right after the accident as, "...[visibility] better than 5 miles, winds variable at 5 to 10 kts, with slightly higher gusts." An archived, base radial velocity image from the NEXRAD radar at Cincinnati, Ohio (elevation 1,171 feet), revealed a wind from the southwest at 20 knots or greater within about 1,500 feet of the surface, at the time of the accident. The terrain between CVG and 8OH9 was rolling. CVG had an elevation of 897 feet. The terrain increased to 914 feet just prior to the Ohio river, and then dropped to 460 feet at the river. After crossing the river, the elevation climbed to 886 feet, and stayed near that for the next three miles, where it dropped to 490 feet, and then climbed to near 800 feet. The heliport was mounted on the roof of one of the buildings. AIRDROME INFORMATION (Destination) The heliport had a lighted concrete surface, which measured 114.5 feet wide and 75 feet deep. The landing perimeter was outlined by red obstruction lights, and lights on the roof of the hangar illuminated the landing area. According to FAA data, the published elevation of the site was 915 feet. The investigation found that the correct elevation was 937 feet. A hangar and building occupied the north side of the landing area. There were three designated landing pads. Pad 1 was on the east-side, pad 2 was on the south side, and pad 3 was on the west side. An illuminated windsock was located on the roof of the hangar, about 40 feet above the landing area. The lead mechanic and lead pilot for PHI at the University Hospital base both reported the windsock would periodically catch on its structure, and at other times was free. There were no photographs taken of the windsock on the night of the accident, and none of the people who initially responded to the scene remembered checking it. Examination of photographs taken by PHI on June 7th revealed that the windsock was free. The windsock was snagged when viewed on May 8, 2000, during the day. The accident investigation te