Indicates Sightseeing Helo May Have Been Overweight

The NTSB has released a factual report from an October 4, 2011 accident in which a sightseeing helicopter went down in the East River in New York City. According to the findings, the Bell 206B was outside its weight and balance envelope at the time of the accident. While three of the five people, including the pilot, survived when the helo went into the water, one was seriously injured and two others were fatally injured.

According to the report, on October 4, 2011, about 1525 EDT, a Bell 206B helicopter, N63Q, crashed into the East River shortly after takeoff from East 34th Street Heliport (6N5), New York, New York. The commercial pilot and one passenger were not injured, one passenger sustained serious injuries, and two passengers were fatally injured. The helicopter was substantially damaged. The helicopter was registered to and operated by a private pilot as a personal flight under the provisions of 14 Code of Federal Regulations (CFR) Part 91. Visual meteorological conditions prevailed, and no flight plan was filed for the local flight. The flight originated from 6N5 about 1524 and was scheduled to return to 6N5.

The pilot reported that the purpose of the flight was to take friends visiting from abroad on a sightseeing flight around New York City. According to the pilot, who was seated in the right cockpit seat, he completed the "before takeoff" check in accordance with the checklist. At takeoff, he brought the helicopter to a 3- to 5-foot hover, made a right pedal turn, and attempted to depart into the wind. He initiated the takeoff to the northeast and continued the turn north, into the wind. He estimated that the helicopter climbed to an altitude of about 30 to 50 feet above the East River, where he felt a small left yaw and then applied the right anti-torque pedal. At that time, he believed that the helicopter was "weathervaning," but he then heard what he thought was the "engine-out" audio warning and thought he had an engine failure.

In response, he initiated a hard right turn back to 6N5 and lowered the collective pitch. He then observed the engine N1 speed to be "up" and concluded that the initial yaw was “weathervaning” and not an engine malfunction. The pilot then increased collective pitch with the intention of conducting a normal landing at 6N5. The nose of the helicopter began an uncommanded yaw to the right. The yaw rate increased rapidly into a spin around the main rotor mast that could not be arrested with full left pedal application.

The pilot believed the helicopter had suffered a tail rotor drive train failure or that he had encountered loss of tail rotor effectiveness (LTE). He lowered the collective pitch and then raised the collective control just before water contact in order to cushion the impact. The helicopter entered the water and rolled inverted.

According to the passenger who was seated in the left cockpit seat, the helicopter moved backwards as it lifted off. The nose was pointed down, and he was leaning forward in his seat against the restraint. The helicopter then began moving "erratically," the pilot made an exclamation similar to “oops,” and the passenger then "knew something wasn't quite right." The helicopter "banked" and began "oscillating from side to side" before it struck the water and rolled inverted. The passenger said that he did not recall hearing any audible warnings or any noises at all.

According to a lineman who was working at 6N5 at the time of the accident, the four passengers arrived at the heliport about 30 minutes before the arrival of the helicopter. Heliport personnel did not provide a passenger briefing. The helicopter arrived about 1517, landed on pad 4, and continued to run. The lineman escorted the passengers to the helicopter and assisted them with their seatbelts while the helicopter was still running. The helicopter took off rearward and climbed to about a 60-foot hover over the river. The helicopter turned left, parallel to the shoreline, and started forward. Then the nose dipped down and the helicopter spun to the left one and one-half turns "out of control" before it collided with the river.

Several witnesses were at or near 6N5 at the time of the accident. They reported that the pilot did not shut down the engine or exit the helicopter before it took off. They observed the helicopter lift off from the helipad, back up over the river, and begin to rotate around the main rotor mast. The helicopter rotated several times before impacting the water. The witnesses reported that the engine sounded normal and that no smoke was coming from the helicopter before impact.

The pilot, age 56, held a commercial pilot certificate with rotorcraft-helicopter, airplane single-engine land, and airplane multiengine land ratings. In the pilot’s logbook, he recorded 2,287 hours of total flight experience, which included 1,482 total hours in rotorcraft and 805 total hours in airplanes. He had 420 hours in the Bell 206 helicopter. During the 90 days before the accident, he recorded 5.1 hours in the Bell 206 and 4.6 hours in multiengine airplanes. During the 30 days before the accident, he recorded 1.7 hours in the Bell 206 and 2.7 hours in multiengine airplanes.

On April 21, 2011, the pilot failed his initial check ride for a commercial pilot certificate. The examination was attempted in a Robinson R44 helicopter with a Federal Aviation Administration (FAA) designated pilot examiner (DPE). The oral examination lasted about 4 hours, and the flight check lasted about 1 hour and 20 minutes. The DPE entered the following remark on the Notice of Disapproval/Application: "Upon reapplication you will be reexamined on the following: takeoff, landing, and go-arounds."

On April 25, 2011, the pilot successfully completed a reexamination. During the reexamination, the oral portion lasted about 1 hour, and the flight check lasted about 30 minutes. The reexamination was performed with the same DPE. The DPE stated in a postaccident interview that LTE and tail rotor malfunctions were covered in the pilot's oral examination.

The helicopter was built in 1976 and registered to the pilot on January 29, 2007. It was powered by an Allison 250-C20 turboshaft engine rated at 400-shaft horsepower. A review of the helicopter maintenance records revealed that the most recent annual inspection was accomplished two days before the accident on October 2, 2011, at an airframe total time of about 11,581 hours. No outstanding discrepancies were listed in the maintenance records.

No weather recording capabilities were available at 6N5. The pilot reported that he did not check the weather before the flight. The nearest reporting stations showed VFR conditions at the time of the flight.

The helicopter was not equipped with crash-protected recording devices. There was no evidence of any nonvolatile memory of investigative value on board the helicopter. An adjacent parking deck security video camera was operating at the time of the accident and captured a portion of the accident sequence. The examined footage, consisting of five frames, appeared to show the helicopter climbing, entering a rotation around the main rotor mast, and descending. An object consistent in appearance with a severed main rotor blade and a splash/spray of water were visible in the air after the helicopter disappeared below the parked automobiles. A search for other local surveillance video sources was unsuccessful.

The helicopter impacted the East River adjacent to 6N5 and came to rest in about 35 feet of water. The wreckage was recovered from the river on the evening of October 4 and transported to the New York Police Department (NYPD) Aviation Unit facilities at Floyd Bennett Field, Brooklyn, New York. Examination of the wreckage revealed no evidence of any preimpact failures or malfunctions of the engine and accessories, main transmission, drive train, main rotor, tail rotor, flight controls, or structure of the helicopter. Additionally, there was no indication of an in-flight fire.

One main rotor blade remained attached to the hub and was bent opposite the direction of rotation. The blade was not fractured. The bends in the blade were consistent with contact with the water while rotating. The other main rotor blade exhibited a chordwise fracture at the outboard doubler. The fracture surface was consistent with bending overload. The outboard section of the blade, about 10 feet long, was not recovered from the East River.

When investigators manually turned the intact main rotor blade, the main transmission rotated with no metallic sounds noted. The long metallic chip detector was removed, and no metallic particles were evident. The short chip detector could not be removed due to surrounding structure deformation. The freewheeling unit operated properly when tested by hand.

All sections of the tail rotor driveshaft assembly were intact, with the exception of the first (farthest forward) section. This fractured section exhibited torsion fracture signatures consistent with a sudden stoppage event from the rear during tail rotor impact with the water. All hanger bearings were free to rotate and showed no signs of distress. The tail rotor gearbox rotated freely by hand with no noticeable binding. Continuity was confirmed from the tail rotor assembly through the tail rotor gearbox to the aft section of the tail rotor driveshaft. The gearbox attachment studs were all intact.

The fractured section of the tail rotor drive shaft was removed and sent to the National Transportation Safety Board’s (NTSB) materials laboratory in Washington, DC, for further examination. Examination of the driveshaft showed deformation patterns and fracture features consistent with a torsion overstress fracture. No indications of fatigue, corrosion, or other preexisting anomalies were observed. For additional information, see the Airworthiness Group Chairman's Factual Report located in the NTSB’s public docket for this accident investigation.

A cursory examination of the engine at the NYPD facilities revealed no obvious anomalies or case ruptures. There was no evidence of fire or thermal distress. The helicopter was equipped with engine inlet duct particle separators. Both separators were free of feathers, bird remains, or other debris. The oil filter impending bypass button was not extended. The throttle was found in the "fly" position, and the position of the throttle and the corresponding positions on the fuel control index indicator were correct. Some fuel was drained and retained for further testing. The engine was then removed from the airframe and shipped to an engine overhaul facility for further examination. The examination showed that the inlet case was intact and all of the inlet guide vanes were in place and showed no apparent damage. The compressor case did not have any bulges or dents. Further disassembly revealed that the compressor rotor was intact and all compressor blades were in place. The compressor stator vanes were intact and did not reveal any apparent damage to the airfoils. The combustor section did not show any evidence of thermal distress, liner wall buckling, or other damage.

Disassembly of the turbine section revealed no thermal distress or breaches in the case. All turbine rotors were intact with no apparent damage to the airfoils. Testing of the engine accessories and fuel system components revealed no evidence of a preexisting malfunction or failure. For additional information, see the Powerplants Group Chairman's Factual Report located in the NTSB’s public docket for this accident investigation.

Toxicology testing was performed on a urine specimen provided by the pilot after the accident. The analysis and toxicology report by the FAA Civil Aerospace Medical Institute, Oklahoma City, Oklahoma, indicated that the specimen was negative for ethanol and drugs.

The aft, left-seat passenger died in a hospital on October 11, 2011, from complications associated with near-drowning. The aft, center seat passenger died at the accident scene from drowning. The aft, right-seat passenger died in a hospital on November 6, 2011, from complications associated with near-drowning. Title 49 CFR 830.2 defines fatal injury as "any injury which results in death within 30 days of the accident." Because this passenger's death occurred 33 days after the accident, she is listed as a "serious injury" in this report. The manner of death for all aft-seat occupants was listed as "accident."

The pilot reported that he requested the lineman at 6N5 to ensure that the three aft-seat passengers had their lap belts on before takeoff. All passengers were wearing headsets, and he advised the passengers to use the doors to exit the helicopter in the case of an emergency. The pilot reported that five packaged life vests were on board the helicopter: three in the rear passenger compartment and two in the forward cabin area. During examination of the wreckage, four packaged life vests were located.

During an interview, the front-seat passenger stated that the pilot verified that he could hear the aft-seat passengers through the headsets; however, there was no additional safety briefing or mention of any life vests on board the helicopter.

The rear passenger seat of the helicopter was equipped with three identical lift-latch style two-point restraints. All of the belts and shackles were undamaged. The lift latches were noted to release when rotated about 30 degrees.

The helicopter was equipped with four forward-hinged, automotive-type doors, two on each side. All four doors were structurally undamaged and functional. There were no placards present on the interior of any of the doors indicating either the closed position or the direction of opening. The Bell Helicopter 206B Maintenance Manual indicated that a placard was to have been installed on the interior of all four doors.
Aircraft Fuel Testing

Fuel samples were collected from the fuel filter bowl on the helicopter and from the fuel truck that serviced the helicopter before it departed Linden, New Jersey, on the day of the accident. The samples were tested for visual appearance, American Petroleum Institute (API) gravity, specific gravity, flash point, and water content. All fuel samples tested were within published criteria for visual appearance, API gravity, specific gravity, and flash point. Water content in the fuel filter bowl was 42 parts per million (ppm). Water content in the fuel truck sample was 54 ppm. There is no published limit for water in jet fuel.

Although there were varying accounts of individual passenger and pilot weights, investigators estimated that the combined weight of the pilot and four passengers was 1,090 pounds. This calculation included 190 pounds for the pilot; 225 pounds for the front-seat passenger; and 225, 265, and 185 pounds for the three aft-seat passengers. The pilot reported that the fuel weight at takeoff was 224.4 pounds.

The helicopter's most recent weight-and-balance check was completed on October 21, 2008. At that time, the calculated empty weight was 1,914.52 pounds. At this empty weight, the estimated gross weight of the helicopter at takeoff was 3,228 pounds. The manufacturer's maximum allowable gross weight at takeoff was 3,200 pounds.

The helicopter was weighed on October 6, 2011, two days after the accident, by a company that specialized in aircraft weight-and-balance services. With some residual water on board (for instance, on the seat cushions, carpet, main transmission, and honeycomb panels) and providing for an intact main rotor system, the empty weight was estimated at 2,146.8 pounds. Therefore, the takeoff weight at the time of the accident was calculated to be 3,461.2 pounds, including the residual water.

The weight-and-balance charts in the manufacturer's Rotorcraft Flight Manual were published to perform weight-and-balance calculations below the maximum allowable takeoff weight of 3,200 pounds. Therefore, interpolation of weight-and-balance data was not performed for either weight-and-balance scenario possible in this accident, as both plotted the weight of the helicopter beyond the maximum allowable gross weight limit of the charts.

The pilot reported that he calculated the total load at takeoff, including passengers and fuel, to be 1,131 pounds. This included 190 pounds for the pilot, 210 pounds for the front-seat passenger, and 155 pounds each for the three aft-seat passengers. He recalled that the three aft-seat passengers reported their weights to him after boarding the helicopter.

In a postaccident interview, the front-seat passenger stated that the pilot did not ask for anyone’s weight, nor did he execute any paperwork or perform any calculations before takeoff. He also stated that when he boarded the helicopter, he told the pilot that his daughter and her friend had decided to go along. He believed that the pilot may not have anticipated the two additional passengers beyond him and his wife.

The FAA issued Advisory Circular (AC) 90-95, “Unanticipated Right Yaw in Helicopters,” in February 1995. The AC stated that LTE was a critical, low-speed aerodynamic flight characteristic that could result in an uncommanded rapid yaw rate that does not subside of its own accord and, if not corrected, could result in the loss of aircraft control. It also stated, "LTE is not related to a maintenance malfunction and may occur in varying degrees in all single main rotor helicopters at airspeeds less than 30 knots."

Paragraph 6 of the AC covered conditions under which LTE may occur and stated the following: "Any maneuver which requires the pilot to operate in a high-power, low airspeed environment with a left crosswind or tailwind creates an environment where unanticipated right yaw may occur."

Paragraph 8 of the AC stated the following:

"OTHER FACTORS...Low Indicated Airspeed. At airspeeds below translational lift, the tail rotor is required to produce nearly 100 percent of the directional control. If the required amount of tail rotor thrust is not available for any reason, the aircraft will yaw to the right."

Paragraph 9 of the AC stated the following:

"When maneuvering between hover and 30 knots: (1) Avoid tailwinds. If loss of translational lift occurs, it will result in an increased high power demand and an additional anti-torque requirement. (2) Avoid out of ground effect (OGE) hover and high power demand situations, such as low-speed downwind turns. (3) Be especially aware of wind direction and velocity when hovering in winds of about 8-12 knots (especially OGE). There are no strong indicators to the pilot of a reduction of translation lift... (6) Stay vigilant to power and wind conditions."

Contributing factors for LTE include high gross weight/density altitude, low indicated airspeed, power droop, and right downwind turns.

FMI: www.ntsb.gov