N80918

HISTORY OF FLIGHT

On February 18, 2016, about 1020 Hawaii-Aleutian standard time, a Bell 206BIII, 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 the provisions of Title 14 Code of Federal Regulations (CFR) Part 91. Visual meteorological conditions prevailed and a company flight plan was filed for the local flight, which originated from Honolulu International Airport (HNL) about 0935.

The pilot reported that, after arriving at work the day of the accident, the helicopter was pulled out of the hangar and that he began his preflight with the company's mechanic's assistant. The pilot stated that they completed "a pretty good preflight," because the flight was the first tour flight since replacement of the tail rotor drive shaft. The pilot further stated that he confirmed fuel quantity and checked other fluids before he retrieved and inspected the life preservers. The pilot then went upstairs to the company's office, met the passengers, showed them the safety video, and stored their belongings.

After he boarded the passengers, whose seat positions were determined by weight and balance calculations, he put the passenger's life preservers on them and secured their seatbelts, the pilot conducted a final walkaround of the helicopter before boarding and starting 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 then flew along the shoreline before flying toward Sacred Valley, then North Shore before turning south to fly down Central Valley, over Wheeler Army Airfield, and on to Pearl Harbor. The pilot said that, as he began the approach to Ford Island, he noticed a vibration throughout the cabin of the helicopter that seemed "different." He decided to return directly to HNL; however, the vibration stopped, and he made a left turn so the 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 to the airport. The controller instructed the pilot to fly to the prison and hold for other inbound helicopters. The pilot stated that, at this point, the vibration developed into a grinding sensation. Then the main rotor low rpm warning light illuminated, and engine rpm began to rise; the point where the engine and rotor RPM needles were no longer matched on the power turbine gauge. The pilot then lowered the collective, reduced the throttle and realized the engine and main rotor were no longer connected as he began to look for a place to land; he selected the grassy area at the Pearl Harbor Memorial visitor's center. Due to his altitude, he said 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, the pilot turned the helicopter slightly left to land in the water as close to shore as possible, with hopes that people would come out to help. 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 located at various locations at the World War II (WWII) 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 of the World War II Valor in the Pacific National Monument. 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. In addition, the pilot held a flight instructor certificate with a rotorcraft-helicopter rating. The pilot held a Federal Aviation Administration second-class medical certificate issued on November 6, 2015, with no limitations. The pilot reported that he was unable to locate his logbook after he was released from the hospital; 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. The helicopter was powered by a Rolls-Royce Allison model 250-C20B turboshaft engine, serial number CAE-832146, with maximum takeoff and maximum continuous power ratings of 420 shaft horsepower. The helicopter was not equipped with an emergency float system.

Figure 1: Helicopter Seating Diagram

The helicopter was equipped with 5 seats, two in the front, and 3 in the aft section of the cabin. The helicopter is flown from the front right seat, with passenger seating in the remaining seats as referenced in figure 1.

According to Bell Helicopter Textron (BHT) 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 (as installed) is comprised of two identical couplings, which are located on either end of the shaft. The internal components consist of two flanges positioned on the ends of the tubular, hollow drive shaft. The assembly requires a retainer ring and packing seal to be positioned against the flange. A drive shaft coupling seal is situated against the packing seal, impeding grease from egressing the coupling assembly.

Figure 2: Engine-to-transmission-driveshaft diagram.

The drive shaft contains a gear sprocket affixed to the shaft flange via 4 bolts (bolt heads positioned on the inside of the coupling). The donut-shaped gear has a hollow area in the middle that aligns with the hollow tube situated between the couplings; a slight lip surrounds the hollow area. 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. The spring (item 6 in figure 2) is positioned between the lip and the end cap of the coupling (grease retainer plate). A retainer ring and packing seal rest against the back plate.

The BHT maintenance manual recommends that, before reassembly, the engine-to-transmission drive shaft couplings be hand-packed with lubricant (C-015 grease) over the top of the internal spline teeth to a depth of 0.2-0.3 inch.

Maintenance Records

Review of maintenance records provided by the operator revealed the following recent inspections.

Table: Recent Helicopter Inspections

No entries referencing a current annual inspection, current 100-hour inspection, or the recent maintenance on the engine-to-transmission drive shaft were located 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.

Maintenance Interviews

Owner of Genesis Helicopters

The owner of the company held a commercial pilot certificate with a rotorcraft rating and a mechanic certificate with airframe and powerplant ratings. He reported that the accident pilot was present during maintenance of the engine-to-transmission drive shaft to observe and pass tools to the mechanics assistant. The owner stated that he witnessed the initial buildup of the shaft, then left the hangar for about an hour to an hour and a half. When he returned, the mechanics assistant had already begun installing the shaft into the helicopter. The owner recalled asking specific questions about the bolts going into the shaft, to include if there was friction on the nuts, to which the assistant responded that there was.

The owner recalled that the helicopter was grounded on January 23 because the rubber seal (which is located at the base of the short shaft) had come apart, and remnants were found on the (engine) deck. Replacement parts were ordered on January 25, and the helicopter was flying again on January 28. The owner estimated that the helicopter had flown 31 hours from the time the seals on the short shaft were replaced to the time of the accident.

When the owner was questioned about the timeframe of the maintenance performed on the short shaft and presented with the helicopter logbooks, he responded that he "can't find them in the logs" and that it "must not have gotten put in the logbooks." When asked what manual was utilized to conduct the maintenance on the short shaft seal, the owner stated that they used the maintenance manual from Bell Helicopters.

When asked how often maintenance looked at the helicopter, the owner stated that there was a daily inspection and he was personally "laying eyes on it every night." After the last flight of the day, the helicopter would be parked outside and looked at before being placed in the hangar for the night. He said the inspection would included checking the security and mounting, checking all the fluids, and visually inspecting the rotor head, lights and seatbelts. He would also examine the grips, bolts, doublers, and the tail rotor and gearbox security and mounting. When asked if he ever looked in the area of the engine-t...