NTSB Factual Report

HISTORY OF FLIGHT

On August 10, 1993, about 1806 hours Hawaii standard time, a Robinson R-22 Beta helicopter, N4017J, collided with the Pacific Ocean following an uncontrolled descent about eight miles southeast of Honolulu, Hawaii. The helicopter was destroyed. The certificated airline transport pilot and his passenger received fatal injuries. The helicopter was being operated by Offshore Helicopters, Incorporated, at the time of the accident. The aircraft, being flown on a personal flight, departed the island of Lanai, Hawaii, about 1725 hours and was destined for Honolulu. Visual meteorological conditions prevailed and a visual flight rules flight plan was filed for the operation.

Acquaintances of the pilot and his wife reported the couple intended to fly the helicopter to various islands for scuba diving activities the day of the accident.

An airframe and powerplant mechanic, who had worked on the accident helicopter, reported seeing the pilot and his wife load diving equipment aboard the helicopter about 1200 hours the day of the accident. He said, "A little while later, I saw them taxiing out to the helipad on the South Ramp at the Honolulu International Airport."

According to the Federal Aviation Administration (FAA) Flight Standards District Office (FSDO) in Honolulu, the pilot and his passenger departed Honolulu International Airport at 1300 hours. The FAA reported the pilot opened a visual flight rules flight plan from Honolulu to the island of Molokai. The pilot radioed that he was west of Molokai and closed his flight plan at 1339 hours. During that radio conversation, the pilot reportedly reopened a new flight plan to the island of Lanai and said that he had two hours and twenty minutes of fuel on board. The FAA reported that at 1349 hours the pilot closed his flight plan.

The activities of the pilot and his wife on the island of Lanai were not established.

The FAA reported that the pilot filed another visual flight rules flight plan while in flight at 1728 hours. The pilot said he was going from Lanai to Honolulu and had two hours of fuel onboard. The FAA said the pilot radioed that he was southeast of Kokohead and closed his flight plan.

According to the FAA, the pilot contacted Honolulu Approach Control at 1806 hours and requested entry into the terminal control area. Approach gave the pilot a transponder beacon code, but the pilot did not respond. Honolulu Approach Control stated they tried to contact the pilot five times without success, then discontinued the attempt. The FAA said the pilot's helicopter was not identified on radar.

Several witnesses located on shore and in a tourist boat offshore heard a loud "explosion" or a metal to metal sound. As they looked up, they reported seeing the helicopter descending until it collided with the Pacific Ocean about eight miles southeast of the Honolulu International Airport, and about 1/4 mile offshore.

One witness reported to the Honolulu Police Department that he was kayaking in the ocean approximately 1/4 mile offshore. He said that he "viewed a helicopter in the sky above, it appeared to be operating properly when all of a sudden it went down into the water." He said he dove down to the helicopter and viewed a male and a female occupant. He said they were "still strapped in and apparently motionless." He said that the Coast Guard and Fire Rescue teams arrived shortly thereafter.

A witness located aboard a tourist boat (a catamaran) said that he was watching the helicopter as it flew past him. He said he saw "the front rotor blades' shaft bend toward the right side of the helicopter." He said the rotor blades began hitting the helicopter "body." The witness reported the helicopter crashed into the water about 50 to 75 feet from the catamaran location.

Several other witnesses reported looking up toward the helicopter after they heard a loud noise. Some said the helicopter fell toward the water and appeared to have one rotor blade. They said the helicopter collided with the water with the left forward section of the fuselage contacting the water first.

According to recorded radar data obtained from the U. S. Navy in Honolulu, the helicopter was flying in a northwesterly direction from the vicinity of the southwest corner of Molokai toward the southeast corner of the island of Oahu. The radar data did not show a directional deviation on the helicopter route of flight. The altitude of the helicopter ranged from about 500 feet above the ocean to about 1800 feet above the ocean during the last 18 minutes of the recorded radar data. The last recorded radar beacon return showed the helicopter at an altitude of about 500 feet above the ocean and approximately 1/4 mile south of the southeastern coast of Oahu.

The accident occurred during the hours of daylight. The accident location was about north 21 degrees and 15.5 minutes latitude and west 157 degrees and 52 minutes longitude.

PERSONNEL INFORMATION

At the time of the accident, the pilot possessed an airline transport certificate with airplane ratings for single engine land, multi-engine land, and airplane instrument. He held a commercial pilot certificate for helicopters.

A pilot's logbook detailing the pilot's helicopter aeronautical experience was recovered. A logbook detailing the pilot's airplane aeronautical experience was not recovered. According to information provided by the FAA, the pilot stated that he had a total of 4,350 hours of aeronautical experience when he applied for his most recent FAA medical certificate on November 17, 1992.

An examination of the pilot's helicopter logbook indicated the pilot had a total of about 140 hours of aeronautical experience flying helicopters, all of which were in Robinson R-22 helicopters. Of that 140 hours, the pilot logged about 73 hours of dual instruction time. The logbook indicated the pilot completed a Robinson Helicopter Company Safety Course in Torrance, California, during March 1993. An endorsement, which appears in the logbook, states the pilot successfully completed his last biennial flight review while attending that course on March 12, 1993.

According to one of the pilot's helicopter instructors, the pilot was "constantly practicing emergency procedures" (in the helicopter). He further reported that the pilot was proficient in Robinson helicopter emergency procedures.

AIRCRAFT INFORMATION

The accident aircraft was a Robinson Helicopter Company R-22 Beta, serial number 1443. According to FAA records and the aircraft's logbooks, it was involved in a previous accident on April 4, 1992.

The helicopter was overhauled by Robinson Helicopter Company and returned to service on July 28, 1993. The helicopter was disassembled and shipped to Honolulu by surface vessel for reassembly.

A logbook entry was made on August 8, 1993, which stated: "The aircraft has been reassembled after ocean shipment in accordance with Robinson Helicopter Company maintenance instructions. Aircraft test flown and returned to service."

At the time of the accident, the helicopter had about five hours of flight time since the airframe and engine were overhauled.

METEOROLOGICAL INFORMATION

The nearest weather reporting station to the accident site is located at Honolulu International Airport, about 8 miles northwest of the accident site. A scheduled surface weather observation was taken by that facility at 1755 hours. That observation, in part, was: "2,500 feet scattered; 4,500 feet scattered; 20.0 statute miles visibility; winds 080 degrees magnetic at 16 nautical miles per hour; temperature 82 degrees fahrenheit; dew point 66 degrees fahrenheit; and altimeter setting of 29.97 inches of mercury."

An examination of weather data indicated that no significant weather was observed, nor forecast, in the vicinity of the accident. No record of any pilot reports (PIREPS) was found which would indicate any significant weather was present in the vicinity of the accident site at the time of the accident.

WRECKAGE AND IMPACT INFORMATION

The accident site is located about 8 statute miles southeast of the Honolulu International Airport and about 1/4 mile offshore in the Pacific Ocean. The helicopter came to a rest at a water depth of about 36 feet on a coral reef.

The helicopter was retrieved from the ocean by a salvage helicopter under the supervision of an FAA airworthiness inspector and was taken to a facility located at Honolulu International Airport.

Underwater photographs and motion pictures were taken of the accident helicopter while it was resting on the coral reef prior to it being retrieved. A comparison of the retrieved wreckage, with the photographs and the motion pictures, indicate no damage to the helicopter occurred during the removal and relocation process and the helicopter components were in the same position as they were when the helicopter was on the coral reef.

An examination of the helicopter's airframe, engine, and major components was conducted.

The engine was removed from the airframe and disassembled. No evidence of a preexisting mechanical failure of any rotating or reciprocating component of the engine was found during the disassembly and examination. All individual blades of the engine cooling fan had symmetrical concave indentures. The lower "V" drive belt sheave had black rubber deposits which matched the damage to the drive belts. No indication that a loss of engine power, prior to the accident occurring, was found.

The cabin had aft crushing from the lower left corner of the cabin. The forward portion of the cabin, including all plexiglass components, was destroyed. One main rotor blade was bent downward from the main rotor mast and was located in the left forward section of the cabin. An examination of metal skin portions of the left portion (co-pilot area) of the cabin revealed indentations which matched the size and shape of the main rotor blade in the area from the inboard forward corner of the overhead glass to a point just forward of the floor-mounted intercom switch. Further indentations were noted in the floor area until a point just forward of the circuit breaker panel, located on the floor, at the forward edge of the left seat bottom.

The fuel tank and the upper steel structure in the vicinity of the fuel tank were displaced to the right side of the helicopter. The fuel tank was located outside of the helicopter. Several of the lower rivets of the fuel tank were "popped."

Several fractures were noted in the helicopter's steel tube structure.

All components of the tail rotor drive train were intact and connected from the clutch shaft aft through the intermediate and aft flex plates to the tail rotor gear box. The intermediate flex plate had some twisting in the direction of powered rotation. Continuity was established by turning the tail rotor drive shaft and observing the resulting movement of the tail rotor hub. The tail rotor blade root fittings were attached to the hub. The pitch change and teeter hinge bearing moved smoothly. A single fracture occurred on one of the tail rotor controls. The fracture occurred at the forward end of the push pull tube just aft of the rod end bearing connecting the tube to the peddle assembly. This fracture occurred at a location of lateral displacement of the airframe. The remainder of the tail rotor controls remained intact. Both tail rotor blades were bent and buckled at their respective root fittings. One tail rotor blade separated in the buckled area and was found on the ocean bottom near the main wreckage. All gears in the tail rotor gear box rotated smoothly and were intact.

One main rotor blade remained intact with some buckling and bending. The other rotor blade was bent downward and was found in and under the left side of the forward cabin section. That rotor blade was bent about 90 degrees at a point about 1/3 of its length from the blade root fitting flange. A second bend occurred at a location about seven inches from the blade tip. The blade tip was missing and not recovered at the accident site. Both main rotor spindles had indentures which matched deformations on the up and down coning stops and flapping stops. The main rotor hub interior had deep gouges where the droop stop tusks contacted the hub. The droop stop tusks were sheared. The remainder of the hub, attachment bolts, and bearings did not display any damage.

The main rotor shaft had marks on both sides which matched the location of the spindles and flapping stops. Both rubber bumpers were missing and the brackets holding them in place were fractured. Just below the flapping stop area, the rotor shaft had buckled and was bent about 45 degrees. In the same area, bulges were noted in the main rotor shaft. The droop stops remained attached to the rotor shaft.

The main rotor mast tube was intact and remained bolted to the lower cap and transmission. Both the lower cap and the upper fitting were intact.

No fractures of the swashplate were noted. All the drive linkages and anti-drive linkages remained intact and functional. All three control push pull tubes remained attached to the lower swashplate. The pitch change links remained attached to the upper swashplate. Both were bent and fractured at the rod end bearings just above the jam nuts.

With the exception of the pitch change links, no fractures were found in the cyclic control system. All of the control tubes remained attached. Some control tubes were bent.

The helicopter's governor assembly and controller were removed for further examination.

An examination of the helicopter's logbooks did not reveal any unresolved discrepancies logged against the helicopter prior to the accident flight.

MEDICAL AND PATHOLOGICAL INFORMATION

Autopsies were performed on the pilot and his passenger by Dr. Kanthi De Alwis, M. D., Pathologist for the Honolulu Medical Examiner's Office on August 11, 1993. The cause of death listed on the reports of autopsy was "Multiple Traumatic Injuries." No preexisting conditions which would have caused or contributed to the accident were noted on the report of autopsy for the pilot.

A toxicological examination was performed on specimens from the pilot by the FAA Civil Aeromedical Institute. Negative results were reported for all screened volatiles and drugs.

TESTS AND RESEARCH

The governor assembly (actuator motor and clutches) and the controller were examined under the supervision of the National Transportation Safety Board at Robinson Helicopter Company, Torrance, California on October 7, 1993.

The cover of the controller was removed. Water was inside the controller. The electrical and electronic components of the governor assembly controller were dried using a hand held electric dryer. A functional test could not be conducted due to water damage.

A test of the mechanical friction clutches showed the friction settings had changed, however, the clutches functioned and remained operational.

ADDITIONAL INFORMATION

The aircraft wreckage was released to Matthew K. Damen, Loss Management Services, Incorporated, on October 12, 1993.

NTSB Probable Cause

A DIVERGENCE OF THE MAIN ROTOR FROM ITS NORMAL PLANE OF ROTATION FOR AN UNDETERMINED REASON(S) WHICH RESULTED IN ROTOR CONTACT WITH THE AIRFRAME.