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On May 5, 2006, approximately 0730 central daylight time (CDT), a single-engine Eurocopter EC120B helicopter, N514AL, registered to and operated by Air Logistics LLC, of New Iberia, Louisiana, was substantially damaged upon impact with the water following a loss of control during initial takeoff climb during takeoff from offshore platform Eugene Island (EI) 120, located in the Gulf of Mexico. The airline transport rated pilot, sole occupant of the helicopter, sustained minor injuries. Visual meteorological conditions prevailed, and a company flight plan was filed for the 14 Code of Federal Regulations (CFR) Part 135 positioning flight. The flight originated from EI 120 approximately 0715, and was destined for EI 105.
The 22,706-hour pilot was interviewed following the accident. The pilot reported that he awoke at 0430 in the morning, got dressed, and carried all of his flight equipment to the helicopter at the platform and proceeded to perform the preflight checks of the helicopter. He added that he sumped the helicopter's fuel system, untied the tie downs, leaving one main rotor blade tied down. The pilot reported that he did not find any discrepancies during the preflight check and then proceeded downstairs to have breakfast and attend the daily platform morning meeting at 0600.
The pilot reported that after being assigned the mission to fly to EI 120, EI 105, EI108, he returned to the helicopter, double-checked all the tie downs were removed and removed the remaining blade tie down. The pilot further stated that he climbed aboard the helicopter and completed the pre-start and engine start as per the checklist. All systems were checked and all systems were found to be operational. The pilot reported that prior to departure, he noted the helicopter had 350 pounds (50 gallons) of fuel on board for the flight, and the radio was set on the Eugene Island radio frequency (129.62).
The pilot reported that prior to bringing the helicopter to a hover, he ran the engine to 100%, brought the helicopter to a hover, and proceeded to hover to the center of the helideck for a pre-takeoff check. All systems and controls were found to be operating normally. The pilot took off on a southeast heading and established a climb at a rate of 500 feet per minute. Somewhere between 300 and 400 feet, the pilot initiated a left turn to a northerly heading. At that time the pilot experienced an uncommanded cyclic movement to the right-forward quadrant and the collective started to come up (increase). The pilot added that the nose of the helicopter pitched-up and the helicopter started to roll to the left.
The pilot stated that he concluded that he was experiencing "a hydraulic failure of some kind," so as per the emergency procedures; he turned the hydraulic control switch on the collective lever to the "off" position. The pilot added that the hydraulic light on the console was activated indicating that the hydraulics were "off." The actions taken by the pilot were not effective and the pilot was not able to regain control of the helicopter. The helicopter continued rolling to the left and entered a spin to the left while the helicopter remained in a nose low attitude. The pilot stated that the helicopter spun for about 3 to 5 revolutions and impacted the water between a 70 and a 90 degree nose-down attitude.
The pilot recalled that about the second spin, he initiated a "mayday" call. The pilot added that the helicopter impacted the water hard. After impacting the water, the helicopter rolled inverted, but continued to float. Prior to exiting, the pilot reported that he discharged the helicopter's float inflation bottle. A rescue boat picked-up the pilot within 5-minutes and he was taken to offshore platform EI 120CF (central facility) where the pilot was examined and received first aid.
There was one eye-witness to the mishap. The witness, a worker at the offshore platform, reported that he was standing on the platform and he observed that after takeoff, the helicopter dropped down pretty close to the sea, then began to rise again in an uncontrolled manner while turning. The witness statement says nothing about seeing whether the blades contacted water prior to impact. The witness stated he "heard the helicopter taking off and saw him drop down very close to the water. The helo then began to rise again in a very uncontrolled way while turning in a very unstable circle. Then the helo tail dropped and the helo turned to the right at the same time. I watched as the helo started to lose lift and start to come back down. I then ran to the P.A. and announced the chopper was going down. As soon as I reached the P.A. I heard him hit."
The wreckage was located at latitude 28 degrees 58.656 minutes North, longitude 91 degrees 28.190 minutes West, about 3/4 of a mile from offshore platform EI 120. The wreckage of the helicopter was retrieved from the water and placed onto offshore platform EI 108, before being transported to the Air Logistics' maintenance facilities in New Iberia, Louisiana.
The aircraft was a Eurocopter model EC120B, assigned serial number 1266, when it was manufactured in France in 2001. The helicopter was powered by a single Turbomeca Arrius 2F turbine engine, serial number 34282. A review of the maintenance records for the helicopter did not revealed any overdue inspections or discrepancies. The helicopter had accumulated a total of 2,728.2 hours at the time of the accident.
On May 8, 2006, an examination of the wreckage was conducted at the operator's maintenance facilities at New Iberia, Louisiana, by representatives from the Federal Aviation Administration, Air Logistics LLC, American Eurocopter LLC, and Turbomeca, under the supervision of an FAA inspector. A detailed examination of the wreckage revealed minimal impact deformation to the fuselage of the helicopter. The forward passenger sliding window was found broken and with portions of the broken window found inside the cockpit area. The damage to the airframe was consistent with the helicopter impacting the water at a 60 to 70 degrees nose low attitude, with low or no forward ground speed, at a very slow rate of descent.
Flight control continuity was established from the cyclic and collective lever to the non-rotating swash plate. Individual lateral, pitch, and collective inputs resulted in proper input to their respective main rotor servo bodies. The left lateral servo was found to be slightly loose from its mount; however, it was still connected at is input and output connections. The antitorque pedals were moved, and proper pitch change was transmitted to the fenestron blades.
A detailed examination of all three of the main rotor blades was conducted at this time. The rotor blades in the EC120B helicopter rotate in the clockwise direction in a yellow-blue-red sequence, with the yellow blade considered as the master blade. All three main rotor blades were found to have sustained impact damage. Only the root area for the red blade was recovered. Approximately 80% of the blue blade was recovered in three main sections, with the lower surface of the blade exhibiting compression damage. The yellow blade was recovered in two main sections. This blade was also found to exhibit compression damage to the bottom (lower) portion of the blade.
The tail rotor drive shaft was found torsionally separated adjacent to the intake, with the direction of separation consistent with a sudden stoppage of the main rotor system (forward of the separation). The tail rotor driveshaft assembly aft of the point of the torsional separation was intact. Rotation of that portion of the shaft resulted in the smooth rotation of the fenestron blades. The tail striker plate and keel were found separated from the lower fenestron fairing.
The four suspension bars for the main gear box (MGB) or main transmission were damaged, with the damage to the two rear suspension bars found to be more severe. The MGB remained attached to the airframe. There was six light-colored impact marks found on the leading edge of the vertical stabilizer. The attenuating seats did not appear to have stroked. Both emergency floats were recovered. Each float consisted of three independent flotation bags. The forward left float bag had been torn. The pilot's live vest functioned normally. No survival factor issues were found during the course of the investigation.
The engine, serial number 34282, had accumulated a total of 2,598.2 hours since new, with 4,553.5 NG cycles and 5,606.5 PT cycles. The serial number for the MO1 was 00609, and the 00611 for the MO2. Engine control continuity was established between the twist grip and the fuel control unit (FCU); however, the forward section of the engine was found to have shifted slightly to the right, while the aft section of the engine had moved to the left, making contact with the rear of the engine cowling. The engine mount was found bent and buckled, with the ears bent rearward. The engine was found seized, and rub marks were found at the compressor blade path. No evidence of foreign object damage (FOD) was found in the compressor or the power turbine. The throttle scale pointer was found at the 46-degree position. The anticipator scale pointer was found at the 48-degree position. The oil filter and fuel filter were found clean. Both magnetic chip detector plugs (front and rear) were found free of chips or debris. Oil was visible in the sight window of the oil tank.
The hydraulic reservoir/pump and servo assembly, the Vehicle and Engine Multifunction Display (VEMD), and the drive adapter and mast assembly were removed from the wreckage for further analysis by the NTSB.
On September 19, 2006, the 3 main rotor servos, part number SC 5091-1 (serial numbers 877, 1393, and 533) and the Hydraulic Power Pack were examined at the Goodrich-SAMM facilities in France under the control and supervision of the BEA. All 3 servo controls were found to be in good condition and performed within limits. The Hydraulic Power Pack was found to have extensive impact damage and the hydraulic pump had separated from the power pack, and was not present at the exam. The actuators and the hydraulic system showed no anomalies and performed within the limits for the manufacturers' specification. The investigation concluded that the control system was installed and properly connected prior to the helicopter impact with the water. No defects or anomalies were found during the examinations that could have prevented normal operation.
All of the rotating components for the drive-train of the helicopter (main rotor blades, the rotor hub, the swash plate, the scissors drive, the free wheel, the main gear box (transmission),etc.,) underwent another detailed examination at the manufacturer's facility in Marignane, France, under the supervision of the BEA. The investigation revealed that the helicopter rotor system sustained two separate impact events, one at a positive and the other at a negative main rotor blade pitch angles. See Eurocopter Material Quality Laboratory Test Report DIQL No. 2006-3185 for details. It was concluded that the positive pitch blade angle impact exceeded the normal pitch range of the blades, evidenced by droop restrainer/droop ring contact marks, indicating external forces (blade impact). The subsequent impact at negative blade pitch angle, evidenced by damage to hub, spherical stops, and blade sleeves, would only have been dimensionally possible with the main rotor drive collar out of place. . The examination concluded that the control system was and properly connected prior to the helicopter impact with the water and that all of the observed damage and fractures were due to overload. No defects or anomalies were found during the examinations that could have prevented normal operation. The reason for the loss of control could not be determined.
The wreckage was released to the operator on August 30, 2007, following the completion of the investigation.