N6100R
Eurocopter AS-350-B2
The pilot stated that as soon as he lifted the helicopter off the platform, he 'felt that something wasn't normal.' He added that he was '2 feet off the deck and turning to the left at the same time.' The surviving passenger stated that it felt as if 'the rear end of the aircraft either got pushed or pulled down.' He added that the nose pitched up violently and then the helicopter bounced (from side-to-side) on the platform. The pilot realized that he did not have enough room to land, and pulled up on the collective in an attempt to get away from the platform. The helicopter then rolled inverted and descended into the water on the north side of the platform. Examination of the platform revealed that the hatch door located on the west end of the platform had a handle that was bent and deformed. On the bottom side of the deformed handle there was a rolled gouge of metal. Under the gouge there was a paint chip. The helicopter's left spring-steel extension had the paint scraped off the upper outboard corner along the length of the extension. Paint analysis and geometric evaluation of the handle and the extension revealed that the paint chip found on the handle and the paint on the spring-steel extension were similar, and that the deformation on the handle coincided with the placement of the extension under the handle.
HISTORY OF FLIGHT On March 17, 1999, at 1302 central standard time, a Eurocopter AS-350-B2 helicopter, N6100R, was destroyed when it impacted water following a loss of control while departing Eugene Island 193 (EI-193), an offshore platform located in the Gulf of Mexico. The helicopter was registered to Banc One Leasing Corporation of Columbus, Ohio, and operated by Petroleum Helicopters Inc. (PHI), of Lafayette, Louisiana. The commercial pilot and one passenger sustained serious injuries, and two passengers were fatally injured. Visual meteorological conditions prevailed, and a company visual flight rules flight plan was filed for the 14 Code of Federal Regulations Part 135 flight. The local on-demand air charter flight to Eugene Island 177 offshore platform was originating at the time of the accident. According to interviews conducted by the investigation team and the NTSB investigator-in-charge (IIC), the pilot stated that it was his third takeoff from EI-193 that day. The pilot stated that he had landed the helicopter on an easterly heading to drop off welding flanges. The pilot did not shut down the engine, nor did any of the passengers exit the helicopter. A platform worker walked up a stairwell (located on the north side of the platform) to the landing area, took the flanges out of the left side helicopter cargo area, and then proceeded back down to a lower level. The pilot stated that he made sure the area was clear, "rolled it up, placed the throttle into the flight gate, armed my floats, and put my horn on." He added that "as soon as [he] picked up, [he] felt something that wasn't normal." The pilot stated that he was "2 feet off the deck and turning to the left at the same time." The pilot stated that he tried to lower the helicopter on to the platform; however, the helicopter would not respond to his control inputs. The pilot said that the helicopter rotated far enough to the left so that he could see down the stairwell through the chin bubble down by his feet. The pilot stated that at one point, he remembered the helicopter hitting hard on the platform. After realizing that he did not have enough room for landing, the pilot pulled up on the collective in an attempt to get away from the platform. The helicopter then rolled inverted and dropped into the ocean on the north side of the platform. The pilot mentioned seeing the platform workers, on the lower levels of the platform, as the helicopter descended into the water. The surviving front left seat passenger stated that he remembered the helicopter lifting off from the platform and feeling "the rear end of the aircraft either [get] pushed or pulled down." The passenger added that the nose pitched up violently and the helicopter "slammed" on the platform from side-to-side. The passenger reported seeing the cyclic control move violently from side-to-side as the helicopter bounced on the platform, and that the pilot could not hold onto the cyclic control. The passenger could remember seeing the stairwell pass underneath the helicopter, but could not remember the helicopter descending into the water. Neither the pilot nor the passenger remembered seeing any warning lights, nor hearing any warning horns. Witnesses on the oil platform, located below the landing pad, stated that they heard a "loud metallic noise" and saw debris flying from above the landing pad. All the witnesses stated that they saw the helicopter fall inverted into the water and observed the floats deploy. The pilot and front passenger were rescued by a boat, which was signaled by another helicopter flying in the area. METEOROLOGICAL INFORMATION According to witnesses and weather reports, the wind at the time of the accident was from the southeast approximately 10 knots. PERSONNEL INFORMATION The instrument rated commercial helicopter pilot was also rated in single-engine land, and multi-engine land airplanes. The pilot was issued a first class medical certificate (with no limitations) on February 26, 1998. The pilot completed a biennial flight review in the AS-350 on November 24, 1998. According to company records, the pilot had accumulated 2,670 total flight hours, of which 157 hours were in the same make and model as the accident aircraft. The three passengers were employed by BP/Amoco to work on the offshore platforms. AIRCRAFT INFORMATION The six-seat helicopter was powered by a 732-horsepower Turbomeca Arriel 1D1 turboshaft engine (serial number 2995). It was maintained under an FAA approved aircraft inspection program (AAIP) on a continuous basis. From January 22, 1999, to February 7, 1999, a Zone 1 and 2 inspection, a 100-hour, 200-hour, 400-hour, 1,000-hour, 2,000-hour and 5,000-hour, or "G" inspection, had been completed at a total airframe time of 4,985.5 hours. The "G" inspection was a manufacturer required, comprehensive inspection conducted by PHI maintenance personnel at 5,000-hour intervals. According to the records, no additional work was performed during the inspections. A "Zone 3" inspection was completed on March 9, 1999. The Zone 3 inspection included examination of the following items: 1. Below Cabin Floor 2. Below Body Structure 3. Landing Gear 4. Left Hand Baggage Hold 5. Rear Structure 6. Right Hand Baggage Hold 7. Instruments 8. Cockpit 9. Cabin 10. Rear Sliding Door (If Installed) 11. Floats 12. General Review of the airplane's maintenance records revealed no noteworthy discrepancies were reported during the Zone 3 inspection. According to the aircraft maintenance records, a worn tail rotor pitch change link was removed and replaced with a "serviceable" pitch change link, S/N 1925, on March 12, 1999, at an aircraft total time of 5,116.75 hours. On March 15, 1999, Airworthiness Directive 98-24-35, which calls for the inspection of the tail rotor pitch change control rod outboard spherical bearing, was complied with at an aircraft total time of 5,123 hours. The mechanic wrote that no discrepancies were noted during the inspection. The helicopter was equipped with emergency floats on the tubular skids, which attach to the fuselage via cross over tubes. The aft cross over tube attached directly to the fuselage. The forward cross over tube was attached to the fuselage's two main structural beams and had shock absorbers attached on the left and right sides. The shock absorbers were mounted on the forward crossover tube by clamps and were attached to the fuselage outboard of the structural attach points. The left and right shock absorbers aided in the prevention of ground resonance during takeoffs and landings. On the aft end of each landing skid was a flat, spring-steel extension measuring approximately 2 inches wide by 8 inches long. Each spring-steel extension was approximately 1/4-inch thick, and attached to the aft end of the landing skid by two bolts. The extensions were cantilever in design and were used as shock absorbers to aid in the prevention ground resonance. AERODOME INFORMATION The offshore platform was a three-level-platform with the helicopter landing area on the top level. The landing area was constructed of steel, overlaid with black and white anti-skid paint. There was a landing circle painted on the top of the platform to indicate ideal positioning. The width and length of 24 feet by 24 feet was indicated on the platform, in a painted square, on the southeast corner of the platform. The landing area was surrounded by a horizontally laid, 62-inch corrugated sheet metal guard, which was overlaid with a chain link fence. This metal guard around the platform served as a safety shelf, and was designed to lie below the landing area. No objects were designed to protrude above the top landing area. There was a stairwell on the north end of the platform, which included a banister that ended just below the top of the platform. The stairwell led down to the second and third levels of the platform. There was a crane positioned on the west side of the platform on the lowest level. Workers on the platform stated that the crane was positioned below the top level at the time of the accident. There were two square hatch doors on the landing platform to facilitate the lowering of heavy equipment from the landing platform to the lower platforms, or vise versa. The two hatch doors extended into the landing circle and were secured in place with latches on the bottom side of the landing platform. There were two handles on each hatch door located opposite each other, near two of the four corners, and placed at 45 degree angles to the corners. When in position on the platform, the hatch door on the west side of the platform had one handle located on the northwest corner of the door and the other handle was located on the southeast corner of the door. The handles were made of 1/2-inch steel barb poles that were bent into a U-shape. The open ends of the barb pole slid down into two oversized holes and were connected on the bottom side of the hatch door by a 1/4-inch thick steel plate welded to the ends. When the handles were not in use, their barb poles laid on top of the hatch door, and were not flush with the top of the platform. According to BP/Amoco records, EI-193 had undergone its last facility inspection on April 25, 1998. No deficiencies were noted with respect to the Rails/Guards/Grating and the Helo Deck Perimeter. WRECKAGE AND IMPACT INFORMATION On March 18, 1999, the NTSB IIC examined the offshore platform. During the examination, sections of the chain link fence that overlaid the corrugated sheet metal were found raised above the west edge of the platform; however, there were no indications of fresh marks or scrapes. On the northeast corner of the platform, the corner section of the corrugated steel and the chain link fence was torn and bent up approximately 2.5 feet. Just to the south of the damaged northeast corner was an indentation in the corrugated steel. The chain link fence, overlying the indentation, was stretched toward the damaged northeast corner. On the landing platform there were fresh scrapes in the black and white anti-skid paint and in the underlying steel. On the south end of the platform there were five fresh scrapes, which averaged about 2 inches in length each. Each scrape consisted of two parallel gouges not more than a 1/4-inch apart. The parallel gouges were about equal in distance apart as the tail rotor leading edge tip and the blade tip's scrape tab. Adjacent to the five scrapes on the south end, light blue paint transfers were visible. The one half of the tail rotor blade, which was recovered from the water the day of the accident, was painted light blue. On this tail rotor blade, there were thick black paint transfers similar to the paint covering the platform. On the northwest end of the platform, three long gouges were visible between the west end hatch door and the stairwell. The gouge nearest the west side hatch door measured about 1 foot in length, and displayed rotational scrapping. The west hatch door's northwest handle was bent toward the west and showed signs of fresh gouge marks on the bottom side of the handle. The gouge had a rolled appearance towards the north. The landing platform's west steel hatch door, with its handles attached, was unlatched, removed, and taken to Materials Analysis of Dallas, Texas, for further examination. There were some fresh gouge marks in the stairwell located on the north end of the platform. On the first step ledge there was a fresh scrape along its edge. Under the ledge was a 3.5-inch long, fresh, gouge paralleling the ledge. Mounted on the submerged stair banister on the north side of the stairwell was a shutoff valve. The shutoff valve sign was bent over the banister towards the north. The banister and the shutoff valve contained gray colored smears similar to the color on the emergency float covers on the helicopter. The following items were located and recovered in the vicinity of EI-193, and were transported to the PHI facility in Lafayette, Louisiana, on March 20, 1999: * the upper and lower main rotor transmission, intact * the upper transmission cowling * the engine/transmission drive shaft * the tail rotor drive shaft or "short" shaft * the starflex, mast, swashplate, and main rotor blades * a section of the tail rotor drive shaft cowling * a section of the left horizontal stabilizer * the emergency floats * a fractured section of the left skid and aft crossover tube, with the spring-steel extension attached. During the recovery, all three main rotor blades were attached to the mast; however, they were removed to facilitate transport. On March 24, 1999, the NTSB IIC examined the recovered parts. The three main rotor blades were fractured and splintered, and displayed leading edge damage. The Thomas Couplings on both ends of the main drive shaft (between the engine and transmission) were warped, bent, and torn, and displayed torsional damage. The main drive shaft also displayed rotational scarring on its outside circumference. The tail rotor "short" shaft (installed between the engine and the tail rotor drive) displayed rotational twisting at the Thomas couplings and circumferential scarring. The tail rotor drive shaft cowling displayed rotational scarring and scraping. The main rotor transmission was intact with the oil cooler and pitch change servos attached. The fore/aft pitch change servo connecting rod was found intact and attached to the servo, but separated from its transmission bay mounted bell crank. The rod-end, which attaches to the fore/aft bell crank, was missing three ball bearings and one bearing dust cover. The fore/aft pitch change connecting rod did not display the same bending or fracture characteristics as the other connecting rods. The fore/aft connecting rod and the main rotor pitch change servos were removed for further examination at the NTSB Materials Laboratory in Washington D.C., and at Materials Analysis of Dallas, Texas, respectively. Both the left and right emergency floats were separated from the helicopter's landing skids. The separated section of the left skid and aft crossover tube displayed 45-degree shear lips along its fractured surfaces. The crossover tube was fractured just below the left side of the fuselage, and displayed characteristics similar to a bending rotational load. The section of left skid and crossover tube, with the spring-steel extension attached was taken to Materials Analysis of Dallas, Texas, for further examination. On April 10, 1999, the fuselage was located and recovered. On April 13, 1999, the NTSB IIC examined the wreckage. The fuselage was found with the tail boom missing aft of the rear baggage area. The right skid and spring steel extension were intact and attached to the helicopter. The right spring-steel extension was found loose. Both left and right skid shock absorbers were fractured near the rod ends. Flight control continuity was confirmed from the cockpit controls to the servo bell cranks in the transmission bay, and the tail boom separation point. The fore/aft bell crank, located in the transmission bay, contained half of the connection pin that secured the fore/aft connecting rod to the bell crank. The pin was present; however, one end appeared to be ripped off, and its surrounding bell crank metal appeared to be torn through. A section of the right skid, with the extension attached, was removed and taken to Materials Analysis for examination. The cockpit's center console pushbutton switches were examined. The master switch, hydraulic test switch, battery switch, and fuel switch were found depressed; however, it could not be determined whether those switches were depressed prior to the helicopter's impact with water and recovery. The pushbutton switch's background lights were examined for filament stretch. The cockpit warning lights were also examined for signs of filament stretch. The console switches contained numerous bulbs with filament stretch; however, none of the caution and warning light filaments were found stretched. The engine, tail boom, tail rotor gearbox, and the other half of the tail rotor blade were not located. MEDICAL AND
the loss of control as a result of the spring-steel extension becoming entangled with the hatch door handle during takeoff. A contributing factor was the flat design of the spring-steel extension.
Source: NTSB Aviation Accident Database
Aviation Accidents App
In-Depth Access to Aviation Accident Reports
