NEWARK, NJ, USA
N44NY
Eurocopter EC-135-P1
The pilot flew the helicopter below and behind the flight path of an airliner, and encountered wake turbulence. He inadvertently rolled the throttles to manual, and never restabilized the engines or main rotor rpm. In addition, he did not understand the reset procedures for the engine controls (FADEC), and never returned the engines to FADEC control. After about 2 minutes of flight with several power changes, and a climb of 700 feet, rotor RPM had decreased to 73%. The pilot declared an emergency, reported a double power loss, and ditched the helicopter in a river. A video of the last several seconds of the flight revealed periodic bursts of flames, and bright objects emitted from the rear of the helicopter before it contacted the water. Although the left engine had been overtempted, and experienced turbine failure, the right engine was capable of producing power at water impact. A failed hydraulic line was found in-line with a failed coupling on the tail rotor drive shaft, in an area where a fire had burned. The mfg reported the tail rotor drive shaft could become unstable above 168% Nr, or lower if the mounts were loose or rubber grommets deteriorated. A sound analysis recorded the main rotor momentarily at 125% Nr during the autorotation. A fault code from the right engine FADEC indicated the power turbine had reached 127% Nr. The hanger bearings for the long tail rotor drive shaft had not been retorqued as required after being replaced. Non-mechanic rated pilots had signed off 100-hour inspections, and required inspections from airworthiness directives.
HISTORY OF FLIGHT On December 3, 1998, about 1742 Eastern Standard Time, a Eurocopter EC-135-P1 helicopter, N44NY, operated by Aerial Films Inc, was destroyed during a precautionary landing in the Passaic River, Newark, New Jersey. The certificated airline transport pilot and camera operator received minor injuries. Night visual meteorological conditions prevailed for the aerial observation flight that originated from Palisades General Hospital Heliport (07NJ), North Bergen, New Jersey, about 1645, and was planned to terminate at Essex County Airport, Caldwell, New Jersey. No flight plan had been filed for the flight, which was conducted under 14 CFR Part 91. The helicopter was engaged in electronic news gathering (ENG) for a local television station, and used a radio call sign of CHOPPER 4. According to the air/ground communications tape from the Federal Aviation Administration (FAA), at 1736:30, the pilot contacted the control tower at Newark International Airport (EWR), Newark, New Jersey, and was cleared into the Class B airspace to cover a story near downtown Newark. The planned route of flight took the helicopter west, across the final approach course for Runways 22L/R. At 1738:02, prior to the helicopter crossing the final approach course, the Newark local controller advised the pilot of traffic, 4 miles away, an MD-80, descending out of 2,000 feet. The pilot was instructed to report when he had the traffic in sight. At 1738:08, the pilot transmitted, "chopper four has the m d eighty, we'll maintain visual separation", which was acknowledged by the local controller. At 1739:05, the pilot transmitted, "chopper four got the next arrival behind the m d eighty." As the helicopter proceeded west toward its destination, the pilot was advised of other helicopters in the same area, and reported that he had visual contact with them. The onboard gyro-stabilized camera was pointed toward Newark airport, and transmitting to the parent television station. An airplane similar in lighting configuration to an MD-80 was seen descending into Newark. At 1739:53, as the helicopter neared the extended centerline of Runway 22L, the camera recorded a momentary vertical oscillation. Both occupants were wearing David Clark headsets. The pilot was talking to the Newark local controller, and the camera operator was talking to the news desk. The camera operator's microphone recorded some of the conversation from the pilot. In addition, the background noise, which consisted of wind, engines, transmission, and the main rotor blades, was also recorded. Following the vertical oscillation, there was a discussion between the pilot and camera operator as to what had happened. The background noise, which had been constant prior to the vertical oscillation, became variable with noticeable increases and decreases in frequency and intensity. According to a transcript of the onboard conversation prepared by the Safety Board cockpit voice recorder laboratory, at 1740:19, the pilot was believed to have stated,"...i'm turning the throttles...." At 1741:16, the pilot said, "turn the light on and get it out so it turns down." According to a Safety Board CVR analysis of the background noise from the onboard recording system, at 1741:48, the main rotor RPM had decreased to 73 percent. At 1741:51, the pilot transmitted, "mayday mayday chopper four is...." The sound analysis of the background noise also revealed a rapid increase in main rotor rpm, to about 125 percent, which occurred at 1741:53, after which the camera operator stopped the onboard recording. At 1741:56, the pilot transmitted, "mayday mayday, our engines are out, we're going down." The Newark local controller acknowledged this. No further transmissions were received from the helicopter. The pilot of another nearby helicopter reported that when he heard the mayday call, he scanned for, and visually acquired "Chopper 4." He then flew toward Chopper 4, and his camera operator aimed their onboard camera at it. The video was about 25 seconds in duration; however, the helicopter was not visually acquired until 9 seconds had elapsed after the start of the tape. The video was initially taken from the right side of, and then from behind Chopper 4. When Chopper 4 was visually acquired, a momentary burst of flame was observed emitting from the helicopter. The source could not be determined. As Chopper 4 continued to descend, the glow of both engines could be discerned. Occasional bursts of flame were seen from the rear of the helicopter; however, the exact location they originated from was not determined. About 5.5 seconds prior to water impact, as the helicopter slowed and descended, bright flashes were observed, and several bright glowing objects exited from the rear of the helicopter and fell toward the ground. During the descent to the water, the helicopter maintained its heading. As the helicopter struck the water, a bright flash was observed near the rear of the fuselage. The flash was obscured by the water spray, after which, the helicopter disappeared from view, and the tape stopped. At 1742:23; the pilot of the following helicopter transmitted to Newark control tower, "he's [Chopper 4] in the water now...." The occupants reported they exited the helicopter and swam to shore. Emergency vehicles were on scene within 2 minutes. When interviewed, the pilot reported that before the crash, the helicopter had encountered a "violent" vertical oscillation which he described as "hard and abnormal", with minimal left-right yawing. He did not recall any noise accompanying the oscillation. He had scanned the gages and everything looked normal. The pilot had seen an airliner about to land at Newark, and thought he may have encountered wake turbulence. His next memory was of being in the hospital. The camera operator reported the helicopter was headed west over the Stickel Bridge toward downtown Newark, when he felt something like a bird strike on the tail rotor blades. He said the vertical oscillation was the largest event he had experienced in-flight. The helicopter momentarily "dropped" and then continued. The camera operator said the pilot thought it was turbulence, but the camera operator reported that he was skeptical. Everything seemed "OK", and the flight continued toward the news story location. The camera operator further reported that when the pilot asked for the light to be turned on, he initially thought the pilot wanted the external searchlight on. However, the pilot reported that he had wanted the overhead internal spotlight shown on the collective mounted throttles, located between the seats. The camera operator also reported that he noticed the main rotor rpm had decreased, and the rotor light had illuminated and stayed on until the helicopter struck the water. The camera operator also reported that during the descent, the helicopter started to become unstable like it was in turbulence. He thought the pilot was visibly shaken, but was still flying, and he tried to get the pilot to relax. The pilot said he was going to put the helicopter down in the river. Further, the camera operator reported in his statement, "...I began to smell what seemed to be burning metal as we continued to descend...." The camera operator reported that he had removed his seatbelt and shoulder harness before touchdown, and upon water impact was not thrown out of his seat. He also opened the left side cockpit door before water impact. The skids hit first, and he exited the helicopter. He felt a main rotor blade strike him in the head after he exited the helicopter. He was uncertain if the helicopter rolled after touchdown. In a follow-up interview, the camera operator reaffirmed there was no noise or yawing of the helicopter, when they encountered the vertical oscillation. It was about the vertical axis only. After the mayday call, the helicopter continued in coordinated flight, while it oscillated. The accident occurred during the hours of darkness, at 40 degrees, 46.10 minutes north latitude, and 74 degrees, 09.42 minutes west longitude. PERSONNEL INFORMATION The pilot held an airline transport pilot certificate. His total flight experience was 3,926 hours, with 123.8 hours in make and model. He had flown 64 hours in the preceding 90 days, with 60 hours in make and model. His last flight review was conducted on November 18, 1997, in a Bell 206. He held a type rating in a Bell 204. He was last issued a FAA first class airman medical certificate, with no limitations, on July 10, 1998. According to documents from American Eurocopter, the pilot was trained on the EC-135, in July 1998, at Morristown, New Jersey. The training included ground school, and 3.2 hours of flight training. The training included operation of the helicopter with engines in manual control, and returning the engines to full authority digital engine control (FADEC) once they were in manual. ORGANIZATIONAL AND MANAGEMENT INFORMATION The helicopter was operated by Aerial Films, Inc, and was under contract to the local NBC affiliate in New York City. The responsibility for pilot training, operations, and maintenance of the helicopter, remained with Aerial Films. Both the pilot and camera operator were employees of Aerial Films. AIRCRAFT INFORMATION The helicopter was manufactured, assembled, and tested in Germany. It was then disassembled and shipped to the American Eurocopter (AEC) facility in Grand Prairie, Texas. The engine and main transmission were serviced with Mobil Jet II, a synthetic lubricant. In Germany, the hydraulic system was serviced with Shell brand Mil-H-5606 fluid hydraulic fluid. At the AEC facility, and in Morristown, New Jersey, the helicopter had been serviced with Texaco brand Mil-H-5606 hydraulic fluid. The helicopter was equipped with a single main rotor and fenestron tail rotor. At 100 percent rpm, the main rotor was turning at 395 rpm, the tail rotor drive shaft was turning at 4,986 rpm, and the fenestron tail rotor was turning at 3,584 rpm. The original standard airworthiness certificate was issued on September 26, 1997. An experimental airworthiness certificate was issued on December 9, 1997, to flight test electronic news gathering equipment that was installed. On December 23, 1997, he helicopter was weighed. On December 24, 1997, the Chief Pilot of Aerial Films conducted a flight test on the installed equipment. On January 19, 1998, the helicopter was issued another standard airworthiness certificate. The helicopter was maintained under an inspection program recommended by the manufacturer, which included pre-flight inspections, 50 hour and 100-hour complementary inspections, a 400-hour intermediate inspection, an 800-hour periodical inspection, and a 12-month inspection. The engines were equipped with electronic controls, manufactured by the Hamilton Sundstrand Corporation, a subsidiary of United Technologies, and referred to by them as electronic engine controls (EECs). All references in the Eurocopter flight manual referred to them as FADECs. The throttles were mounted on the collective with the forward throttle for the left engine, and the rear throttle for the right engine. A white line and the letter N on the throttles, which aligned with a white arrow on the collective, identified the neutral position of the throttles. There was a noticeable detent when the throttle was rolled across the neutral position, which matched the painted positions that were mid-way between the full open and minimum idle positions. Normal flight was conducted with the throttles in the neutral position, and with control of the engines conducted by the FADECs. The FADECs provided several functions, which included the scheduling of fuel and maintaining engine operation within pre-determined limits. The helicopter was equipped with a red warning light for main rotor rpm speed. When the main rotor rpm was above 106 percent, the light would flash, and when below 95 percent, the light would be illuminated in a steady state. The green arc on the main rotor tachometer was from 80 percent to 106 percent. The helicopter had two fuel tanks, the supply tank, and the main tank. The supply tank was fed from the main tank and was used as constant source of fuel for the engines. In normal operations, the supply tank would remain full until the main tank was empty, after which the fuel would decrease in the supply tank. Fuel added to the main tank moved the center of gravity forward. Fuel added to the supply tank moved the center of gravity rearward Examination of weight and balance data for the helicopter revealed the empty weight of the helicopter was 1,882.49 kilograms (kg). The maximum allowable gross weight was 2,720 kg. The weight of the helicopter at the time of accident was estimated to be 2,507 kg. The center of gravity was estimated to be 49 millimeters (1.93 inches) forward of the forward limit. According to Advisory Circular 61-13B, Basic Helicopter Handbook, Chapter 7, Weight and Balance, "Out of balance loading of the helicopter makes control more difficult and decreases maneuverability since cyclic stick effectiveness is restricted in the direction opposite to CG location." RADAR AND OTHER REMOTELY RECORDED DATA Recorded radar data was obtained from the New York Terminal Area Radar Control (TRACON). The track and altitude of the helicopter, along with several arriving airplanes were plotted. The last airplane to arrive prior to the passage of the helicopter was identified as a MD-82. The data revealed that the helicopter passed behind the MD-82, 200 feet below, at an altitude of 700 feet MSL, and 36 seconds after its passage. Over the next 2 minutes, the helicopter continued to the west and then north. It also climbed from 700 feet to an altitude of 1,400 feet. WRECKAGE AND IMPACT INFORMATION The helicopter came to rest on its left side in about 6 feet of water. Divers reported that the tail boom was physically separated from the fuselage, and restrained by a steel cable, which was later identified as the control cable to the fenestron tail rotor. The control cable was cut, and the fuselage and tail boom removed from the river. The helicopter was then transported to Teterboro Airport (TEB), Teterboro, New Jersey, for further examination. The fuselage floor was fractured between the middle and rear rows of seats. The paneling on the bottom of the fuel tank was not recovered. However, the fuselage fuel tank bladder mounted in the lower aft fuselage was not ruptured or leaking. The helicopter was equipped with attenuating seats that were designed to collapse downward under increased "g" loads. Post-accident examination revealed that both occupied crew seats had collapsed downward, and neither occupant received serious injuries. The main rotor blades were found with splits on the skin at the trailing edge of the blades. In addition, two blades were fractured, perpendicular to the plain of rotation. Small indentations and breaks were found on the leading edges of the blades. In addition, there was an indentation on the left side of the tail boom, which was consistent with a main rotor blade strike. None of the main rotor pitch link control rods were broken. Breaks were observed in the flight control system in the following locations: rudder bell crank, right lateral cyclic, and aft cyclic. All fractures had bright granular surfaces. In addition, a collective push rod tube was crushed, and the control cable for the fenestron tail rotor had been cut before the tail boom and helicopter were removed from the water separately. All other connections in the flight control and tail rotor control system were intact. Flight control continuity was confirmed for other than the previously mentioned conditions. Aft Fuselage The aft fuselage behind the passenger cabin was divided into upper and lower sections. The lower section housed electronic components, and had space for a baggage compartment. The upper section housed several components including the main transmission, both engines, two firewalls, and the forward portion
the pilot's failure to maintain proper rotor rpm and his improper in flight decision to enter autorotation due to his lack of knowledge of the power plant controls. Factors in the accident were the night conditions and the pilot's improper decision to fly through wake turbulence.
Source: NTSB Aviation Accident Database
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