B.S. 53, LA, USA
N3194P
Bell 206L-1
The on-demand offshore helicopter flight impacted an oil platform during landing. The pilot stated that he was performing a standard pinnacle approach to the helipad. The approach was described as normal until the helicopter crossed over the edge of the platform, at which point the helicopter suddenly descended below the approach path. He reported that an increase of power beyond 100% torque was ineffective in arresting descent rate. The platform was equipped with a windsock located to southeast side of the landing pad. The height of the windsock was such that it intersected the approximate plane formed by the helideck. The windsock was tattered and according to the pilot's report, "the end of the windsock was wrapped around the pole." Disassembly of the engine revealed no anomalies.
HISTORY OF FLIGHT On January 16, 2003, at 0826 central standard time, a Bell 206L-1, N3194P, operated by Air Logistics LLC, was destroyed on impact with an offshore platform during landing. A post crash fire ensued. Visual meteorological conditions prevailed at the time of the accident. The 14 CFR Part 135 business flight was operating on a company flight plan. The commercial pilot and two passengers were seriously injured, and the third passenger was fatally injured. The flight departed from Air Logistics (Venice) N Heliport (45LA), Venice, Louisiana, at 0816, en route to the platform. Company records indicate that the pilot began his duty day at 0500 and flew two flights in the accident helicopter prior to the accident flight. He departed from 45LA at 0708 and arrived at MP133 at 0744. He then departed at 0744 and returned to 45LA at 0816. He then departed on the accident flight to Breton Sound 53. According to National Safety Transportation Board (NTSB) Form 6120.1/2 submitted by the pilot's attorney, the pilot reported: "I noted the position of the windsock. The tail of the windsock was pointing toward the north. I also observed the direction of the 'wind streaks' on the surface of the water, which supported the indications of the windsock. I estimated the wind to be light (approx. 5 knots) coming out of the south, the sky was clear, visibility unrestricted, and weather was not a factor. I completed the Before Landing Checklist upon entering the downwind leg. Abeam the platform I started a slow descent and a right hand turn, rolling out of the turn as I intercepted the final approach path to the platform, utilizing AirLog's standard "pinnacle" approach. I continued the approach to the south, into the wind, on a relatively shallow final approach (standard for a "pinnacle" style landing). Throughout the approach I continuously scanned my instruments, particularly the Vertical Velocity Indicator (VVI), which confirmed 500 feet per minute descent. The 500 feet per minute descent was normal for this type of approach. The approach proceeded normally until I crossed over the edge of the platform, at which point the helicopter suddenly descended below the approach path I was flying. At this time I initiated an increase in power eventually reaching 100% torque which was ineffective in arresting the descent. Given the weather conditions, gross weight and power available according to manufacturers specifications (see attached Out of Ground Effect Hover Power chart excerpted from the flight manual) there should have been more than sufficient power to arrest the sink rate. With no room to maneuver and no way to get clear of the platform, I increased power beyond 100% in a final attempt to gain the helideck with no recovery of altitude. At this time there were no other options available as the aircraft began an uncontrolled right-hand turn and the main or tail rotor blades struck obstacle on the platform. The aircraft came to rest on its right hand side on the superstructure of the platform." According to the a statement submitted by the passenger's employer, a passenger reported: "We were making our final approach to land on the helo-deck at Breton Sound 53, when I was thinking that the pilot was coming in too fast. He was looking back and forth to check the landing pad. The pilot is hovering over the pad and looking around. The tail of the helicopter was lowered during the approach. The pilot put her down and then the helicopter felt like it was sliding off the side of the helipad. The pilot tried to gain control but it seemed that the RPMs were too low and the pilot could not recover. The main rotor then struck some piping making the helicopter flip from side to side." AIRCRAFT INFORMATION The 1983 Bell 206L-1, serial number 45788, was registered and operated by Air Logistics LLC. The helicopter was powered by a Rolls Royce Allison 250-C28B, serial number CAE-860263 engine. The helicopter accumulated a total airframe time of 12,036.1 hours and 43 hours since its last phase inspection. The helicopter had a maximum approved internal gross weight for takeoff and landing of 4,150 pounds. The longitudinal center of gravity (CG) limits for internal loading were as follows: forward limit was 118 inches up to 2,800 lbs changing linearly to 119.1 inches at 4,150 lbs, aft limit was 128.5 inches up to 2,900 lbs changing linearly to 126.85 inches at 4,150 lbs. According to an estimated weight and balance of the accident flight prepared by the operator, the helicopter had a landing weight of 3,901 lbs and a CG of 123.1 inches. The pilot reported in his statement that the gross landing weight was 3,820 lbs. PERSONNEL INFORMATION The pilot, age 35, held a commercial pilot certificate with airplane single-engine land, multiengine land, helicopter, instrument airplane, and instrument helicopter ratings. He was hired as a charter pilot on August 27, 2001, by Air Logistics LLC. On August 30, 2001, he completed the company's initial pilot training. From September 2, 2001 to September 24, 2001, he received and completed the company's initial flight training during which he received 18.7 hours of flight training of which 7.5 hours were offshore flying. On September 24, 2001, he received an 14 CFR Part 135 Airman Proficiency/Qualification Check in a Bell 206 with "satisfactory" results. On October 15, 2002, he received company recurrent training and completed his last Airman Proficiency/Qualification Check with "satisfactory" results. The training was comprised of 0.5 hours under the hood and included: steep turns, unusual attitude recovery, maneuver by partial panel According to NTSB Form 6120.1/2, the pilot accumulated a total flight time of 3,075.8 hours of which 398.3 hours were in the make and model of the accident helicopter. He accumulated 52.5 hours of flight time in the accident make and model in the last 30 days. The pilot was issued a first class airman medical certificate with no waivers or limitations on March 19, 2002. METEOROLOGICAL INFORMATION A Meteorological Group Chairman Report is included in the docket of this report. The report states that a northeast-southwest oriented cold front extended across central Louisiana. Surface weather plots east of the cold front generally showed light southeasterly-southerly winds. In addition, the plots showed temperatures in the 40s and 50s Fahrenheit (F) over land and in the low 60s F at weather buoys over the northern Gulf of Mexico. The report contains recoded weather observations from the following stations relative to B.S. 53: Boothville (BVE), Louisiana, located about 246 degrees and 15 nautical miles (NM): At 0751, wind variable at 6 knots; visibility 10 statute miles (SM); sky condition overcast 7,500 feet; temperature 10 degrees Celsius (C); dew point 09 degrees C; altimeter setting 30.23 inches of mercury (hg). At 0851, wind 050 degrees at 6 knots; visibility 10 SM; sky condition broken 6,000 feet overcast 7,500 feet; temperature 10 degrees C; dew point 09 degrees C; altimeter setting 30.23 inches hg. New Orleans Naval Air Station Air Safety (NBG), Louisiana, located about 298 degrees and 52 NM: At 0755, wind 060 degrees at 4 knots; visibility 6 SM; haze; overcast 5,000 feet; temperature 10 degrees C; dew point 7 degrees C; altimeter setting 30.23 inches hg. At 0855, wind 110 degrees at 3 knots; visibility 7 miles; sky condition broken 5,000 feet; temperature 10 degrees C,; dew point 07 degrees C; altimeter 30.23 inches hg. Gulfport-Biloxi Regional Airport (GPT), Missouri, located about 003 degrees and 59 NM: At 0753, wind calm; visibility 7 SM; few clouds 6,500 feet overcast 8,000 feet; temperature 08 degrees C; dew point 08 degrees C; altimeter setting 30.23 inches hg. At 0853, wind 130 degrees at 4 knots; visibility 9 SM; overcast 7,000 feet; temperature 9 degrees C; dew point 9 degrees C; altimeter setting 30.22 inches of hg. Buoy 42007, located 024 degrees and 44 NM: At 0800, wind 042 degrees at 12 knots; wind gust 13 knots; temperature 10 degrees C; dew point 6 degrees C. At 0900, wind 083 degrees at 11 knots; wind gust 13 knots; temperature 11 degrees C; dew point 7 degrees C. Buoy 42040, located 105 degrees and 51 NM: At 0800, wind 150 degrees at 8; wind gust 11 knots; temperature 18 degrees C; dew point 13 degrees. At 0900, wind 143 degrees at 9 knots; wind gust 11 knots; temperature 18 degrees C; dew point 13 degrees C. Southwest Pass C-MAN (BURL1), located 206 degrees at 35 NM: At 0800, wind 010 degrees at 9 knots; temperature 12 degrees C; peak wind gust 10 knots; wind speed at 10 meters above the site 9 knots; wind speed at 20 meters above site 9 knots; time of maximum wind speed 0700; maximum wind speed and direction 350 degrees at 18 knots. At 0900, wind 360 degrees at 11 knots; temperature 11 degrees C; peak wind gust 12 knots; wind speed at 10 meters above site 10 knots; wind speed at 20 meters above site 11 knots; time of maximum wind speed 0856; maximum wind speed and direction 010 degrees at 12 knots. Grand Isle C-MAN (GDIL1), located 258 degrees and 44 NM: At 0800, wind 050 degrees at 6 knots; temperature 11 degrees C; peak wind gust 7 knots; wind speed at 10 meters above site 6 knots; wind speed at 20 meters above the site 6 knots; time of maximum wind speed 0709; maximum wind speed and direction 040 degrees at 9 knots. At 0900, wind 350 degrees at 4 knots; temperature 10 degrees C; peak wind gust 5 knots; wind speed at 10 meters above site 4 knots; wind speed at 20 meters above site 4 knots; time of maximum wind speed 0829; maximum wind speed and direction 340 degrees at 12 knots. AIRPORT INFORMATION The BS 53 "A" production platform was located about 14.6 NM and 059 degrees from 45LA. The platform was equipped with a windsock located southeast of the landing pad. The height of the windsock was such that it intersected the approximate plane formed by the helideck. The windsock was tattered and according to the pilot's report, "the end of the windsock was wrapped around the pole." WRECKAGE AND IMPACT INFORMATION The wreckage diagram, which is included in the docket of this report, depicts debris lying to the east of the helideck and on the production platform. The cabin area, main rotor blades, and main rotor hub were lying between two platform generators, which were oriented towards northeast and southwest. The tail rotor gearbox was lying along the southwest face of the southwestern generator. A main rotor blade was north of the two generators. The western most piece of debris consisted of a tail rotor section. TESTS AND RESEARCH The engine was shipped to Rolls Royce Allison in Indianapolis, Indiana, for a disassembly examination under the supervision of a Federal Aviation Administration (FAA) inspector. The engine was covered with soot and had fire damage to the exterior lines and wiring consistent with a post crash fire. Disassembly of the turbine section revealed that the number one turbine wheel had some light rub marks on its blade tips and the number three nozzle had some light rub marks on the blade track area, both of which were consistent with engine rotation on impact. Disassembly of the compressor section revealed that the compressor shroud had molten aluminum splatter on the interior consistent with rotation during the exterior fire. The impeller of the compressor did not display any rotation marks. The Rotorcraft Flying Handbook, FAA-H-8083-21, Chapter 11, Helicopter Emergencies, Vortex Ring State (Settling With Power), states: "Vortex ring state describes an aerodynamic condition where a helicopter may be in a vertical descent with up to maximum power applied, and little or no cyclic authority. The term "settling with power" comes from the fact that helicopter keeps settling even though full engine power is applied. In a normal out-of-ground-effect hover, the helicopter is able to remain stationary by propelling a large mass of air down through the main rotor. Some of the air is recirculated near the tips of the blades, curling up from the bottom of the rotor system and rejoining the air entering the rotor from the top. This phenomenon is common to all airfoils and is known as tip vortices. Tip vortices consume engine power but produce no useful lift. As long as the tip vortices are small, their only effect is a small loss in rotor efficiency. However, when the helicopter begins to descend vertically, it settles into its own downwash, which greatly enlarges the tip vortices. In this vortex ring state, most of the power developed by the engine is wasted in accelerating the air in a doughnut pattern around the rotor. In addition, the helicopter may descend at a rate that exceeds the normal downward induced-flow rate of the inner blade sections. As a result, the airflow of the inner blade sections is upward relative to the disc. This produces a secondary vortex ring in addition to the normal tip-vortices. The secondary vortex ring is generated about the point on the blade where the airflow changes from up to down. The result is an unsteady turbulent flow over a large area of the disc. Rotor efficiency is lost even though power is still being supplied from the engine. A fully developed vortex ring state is characterized by an unstable condition where the helicopter experiences uncommanded pitch and roll oscillations, has little or no cyclic authority, and achieves a descent rate, which, if allowed to develop, may approach 6,000 feet per minute. It is accompanied by increased levels of vibration. A vortex ring state may be entered during any maneuver that places the main rotor in a condition of high upflow and low forward airspeed. This condition is sometimes seen during quick-stop type maneuvers or during recoveries from autorotations. The following combination of conditions are likely to cause settling in a vortex ring state: 1. A vertical or nearly vertical descent of at least 300 feet per minute. (Actual critical rate depends on the gross weight, r.p.m., density altitude, and other pertinent factors.) 2. The rotor system must be using some of the available engine power (from 20 to 100 percent). 3. The horizontal velocity must be slower than effective translational lift. Some of the situations that are conducive to a settling with power condition are: attempting to hover out of ground effect at altitudes above the hovering ceiling of the helicopter; attempting to hover out of ground effect without maintaining precise altitude control; or downwind and steep power approaches in which airspeed is permitted to drop to nearly zero. When recovering from a settling with power condition, the tendency on the part of the pilot is to first try to stop the descent by increasing collective pitch. However, this only results in increasing the stalled area of the rotor, thus increasing the rate of descent. Since inboard portions of the blades are stalled, cyclic control is limited. Recovery is accomplished by increasing forward speed, and/or partially lowering collective pitch. In a fully developed vortex ring state, the only recovery may be to enter autorotation to break the vortex ring state. When cyclic authority is regained, you can then increase forward airspeed." ADDITIONAL INFORMATION: The FAA, Air Logistics L.L.C., Bell Helicopter, Rolls Royce Allison, and the Department of the Interior were parties to the investigation. The Transportation Safety Board of Canada was a designated representative to the investigation. The wreckage was released to Air Logistics L.L.C.
The improper approach by the pilot and the settling with power encountered by the pilot.
Source: NTSB Aviation Accident Database
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