History of Flight
On February 18, 2016, about 1020 Hawaii-Aleutian standard time, a Bell 206BIII, registration N80918, was substantially damaged when it impacted water during a forced landing near Honolulu, Hawaii. The commercial pilot and two passengers sustained serious injuries, one passenger sustained minor injuries, and one passenger was fatally injured. The helicopter was privately owned and operated by Genesis Helicopters as a commercial air tour flight under Title 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed, and a company flight plan was filed for the local flight, which originated from Honolulu International Airport about 0935.
The pilot reported that after arriving at work, the helicopter was pulled out of the hangar, and he began his preflight with the company's mechanic's assistant. They completed a preflight because the flight was the first tour flight since replacement of the tail rotor drive shaft. He confirmed fuel quantity and checked other fluids before retrieving and inspecting life preservers. After boarding passengers, whose seat positions were determined by weight and balance calculations, he put life preservers on them and secured seatbelts, conducted a final walkaround, then boarded and started the engine.
After departure, the flight proceeded to fly the Shoreline 6 departure procedure to crossover to the east side of Oahu Island. The pilot flew along the shoreline before flying toward Sacred Valley, then North Shore, then turned south to fly down Central Valley, over Wheeler Army Airfield, and on to Pearl Harbor. As he began the approach to Ford Island, he noticed a vibration throughout the cabin that seemed "different." He decided to return directly to HNL; however, the vibration stopped, and he made a left turn so passengers could see the USS Arizona Memorial.
Shortly thereafter, the vibration returned, and the pilot called the air traffic control tower at HNL to advise that the flight would be returning. The controller instructed the pilot to fly to the prison and hold for other inbound helicopters. The pilot stated that the vibration developed into a grinding sensation. Then the main rotor low rpm warning light illuminated, and engine rpm began to rise; the engine and rotor RPM needles were no longer matched. The pilot lowered the collective, reduced the throttle, and realized the engine and main rotor were no longer connected. He began to look for a place to land and selected the grassy area at the Pearl Harbor Memorial visitor's center. Due to his altitude, he tried to increase his sink rate to make the selected landing area and put the helicopter "back in trim to land" before he noticed people disembarking from the USS Arizona Memorial ferry vessel in his selected landing area. To avoid the people, he turned the helicopter slightly left to land in the water as close to shore as possible. He stated that when the helicopter was about 20 ft above the water, it felt like the rotor stalled, the helicopter lost lift, and it "fell out of the sky." The helicopter descended rapidly into the water about 20 ft from the shoreline.
Witnesses at various locations at the World War II Valor in the Pacific National Monument reported seeing the helicopter at a low altitude before it suddenly descended into the water. A review of video captured by a witness revealed that the helicopter was approaching the Contemplation Circle area. The helicopter's forward airspeed appeared to decrease, the nose pitched up, and the helicopter began to rotate to the left in a slightly nose-up attitude then descended rapidly into the water. At the time of impact, the helicopter appeared to be in a slightly nose-high, left bank attitude.
Personnel Information
The pilot held a commercial pilot certificate with rotorcraft-helicopter and instrument helicopter ratings, and a flight instructor certificate with a rotorcraft-helicopter rating. He held a Federal Aviation Administration second-class medical certificate issued on November 6, 2015, with no limitations. He estimated that at the time of the accident he had accumulated about 900 total hours of flight experience, with 151 hours in the accident helicopter make/model and 125 hours within the previous 90 days.
Aircraft Information
The accident helicopter was a Bell Helicopter model 206, serial number 2687, powered by a Rolls-Royce Allison model 250-C20B turboshaft engine. The helicopter was not equipped with an emergency float system. It was equipped with 5 seats: two in the front and three in the aft section. The helicopter is flown from the front right seat.
According to a Bell Helicopter Textron representative, an integral part of the helicopter's power train system is the engine-to-transmission drive shaft, located between the transmission and freewheeling drive. The drive shaft is comprised of two identical couplings on either end of the shaft. The internal components include two flanges on the ends of the tubular hollow drive shaft. The assembly requires a retainer ring and packing seal against the flange, and a drive shaft coupling seal against the packing seal to impede grease egress. The drive shaft contains a gear sprocket affixed to the shaft flange via 4 bolts. The outer coupling gear surrounds the drive gear where it is splined, and torque is transmitted. Inside the coupling, the assembly is equipped with a shaft centering spring.
Maintenance Records
Review of maintenance records provided by the operator revealed no entries referencing a current annual inspection, current 100-hour inspection, or recent maintenance on the engine-to-transmission drive shaft within the airframe and engine logbooks. The most recent maintenance entry was the replacement of a tail rotor drive shaft segment on February 17, 2016, at an airframe total time of 15,516.5 hours.
Interviews with the owner of Genesis Helicopters, the pilot, and the mechanic's assistant provided details about recent maintenance. The owner stated that the accident pilot was present during maintenance of the engine-to-transmission drive shaft. The mechanic's assistant, who did not hold a mechanic certificate, reported that the "short shaft" had been removed due to leaking grease on January 25. During reassembly, he re-used the same nuts, bolts, and washers.
Wreckage and Impact Information
Examination of the accident site revealed the helicopter submerged about 40 ft under water about 20 ft from the shoreline. The helicopter was removed the following day and rinsed with fresh water. The main rotor blades, mast, transmission, engine, tailboom, tail rotor gearbox, and tail rotor blades remained attached. The aft portion of the fuselage was compressed upward. The windshield and both lower bubble windows were impact damaged and mostly separated. None of the doors were installed at the time of the accident.
Tail rotor drive continuity was established from the tail rotor forward through a torsional fracture in the #3 tail rotor drive segment to the oil cooler blower shaft, the forward short shaft, and the freewheeling shaft. Continuity was observed from the mast through the transmission when the main rotor blades were turned by hand, though the forward end of the engine-to-transmission drive shaft was not rotating properly. The four bolts holding the outer coupling were loose with no torque stripe present. Two of the four bolts holding the inner coupling were missing. Two sheared bolt heads were located; the remainder of the bolts and nuts were not recovered. The forward retaining ring was still in place, but only the center of the retainer plate was found, and the centering spring was fractured/deformed. The outer coupling was missing the three temperature plates. No visible evidence of any grease on the inner/outer coupling was observed. The gear teeth on the inner gear coupling were worn away.
Examination of the recovered engine revealed no evidence of mechanical anomalies that would have precluded normal operation. The transmission was examined; internal components were heavily corroded from saltwater immersion, but no evidence of preimpact malfunction was observed.
Survival Aspects
A witness, a Federal Police Officer at the WWII Valor in the Pacific National Monument, reported that after the accident, 3-4 people dove into the water to rescue a 16-year-old passenger trapped inside the helicopter, seated in the aft middle seat. The officer and a Navy diver took turns cutting the straps off the passenger underwater. After about 5-6 attempts, they brought the passenger to the surface, and CPR was immediately administered by nurses and doctors visiting the memorial; an AED was also used. The officer did not remember if the passenger's life preserver was inflated but recalled seeing yellow underwater; the life preserver was tangled with the seatbelts. Another witness reported the helicopter was underwater for about 15 minutes before the passenger was extracted. A registered nurse who assisted reported removing an uninflated flotation device during initial treatment. Review of treatment records for the passenger revealed evidence consistent with drowning and no traumatic injuries to the head or neck. Examination of the passenger's life preserver revealed cut straps on the back, a functioning waist band clasp, no visible damage to the inflatable portion, and a punctured CO2 cartridge consistent with inflation. No inspections were recorded on the periodic maintenance tag. It could not be determined when or how the life preserver was inflated.