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N135UW accident description

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Tail numberN135UW
Accident dateMay 10, 2008
Aircraft typeEurocopter Deutschland Gmbh Ec 135 T2+
LocationLa Crosse, WI
Near 43.841944 N, -91.165556 W
Additional details: None

NTSB description

The following is an INTERIM FACTUAL SUMMARY of this accident investigation. A final report that includes all pertinent facts, conditions, and circumstances of the accident will be issued upon completion, along with the Safety Board's analysis and probable cause of the accident. ---------------------------------------------------------------------------------------------------

HISTORY OF FLIGHT

On May 10, 2008, about 2245 central daylight time, a Eurocopter Deutschland GmbH EC 135 T2+ air medical configured helicopter, N135UW, operated by Air Methods Corporation, was destroyed during an in-flight collision with trees and terrain near La Crosse, Wisconsin. The flight was conducted in accordance with 14 Code of Federal Regulations Part 91 without a flight plan. Night visual meteorological conditions prevailed. The pilot, physician and flight nurse sustained fatal injuries. The flight departed La Crosse Municipal Airport (LSE), La Crosse, Wisconsin, at 2234. The intended destination was the University of Wisconsin Hospital heliport (WS27) in Madison, Wisconsin.

The helicopter was equipped with global positioning system (GPS) tracking equipment that provided departure, arrival and en route position information to the operator’s Operations Control Center. Flight progress was automatically updated approximately every three minutes. According the GPS flight-following data, the flight initially departed WS27 about 2038 en route to Prairie du Chien Memorial Hospital, Prairie du Chien, Wisconsin. The flight arrived there about 2113 and picked up a patient. The flight subsequently departed about 2131 and proceeded to Gunderson-Lutheran Hospital in La Crosse, arriving about 2154. After dropping off the patient, the crew departed about 2209 and repositioned the helicopter to LSE for refueling. The flight departed LSE at 2234 with the intention of returning to WS27. No further position updates were received from the accident helicopter.

The line service technician who fueled the aircraft noted that when it departed it lifted off vertically and proceeded east-southeast. He added that there was a low ceiling, fair visibility and moderate rain at the time.

A witness located approximately 4.2 miles east-southeast of LSE reported hearing a helicopter fly over about 2230. He was in a restaurant parking lot getting into his car at the time. He noted that it sounded like Medlink helicopter. He reported that it was "traveling at a high rate of speed, and was flying low." He recalled thinking that it wasn’t going to clear the bluffs.

A resident contacted the La Crosse County Sheriff's Office about 2240 and stated that he heard a helicopter flying overhead, when the sound of the engine disappeared followed by a loud crashing sound. Local authorities initiated a search at that time.

At 2304, the helicopter operator notified local authorities that the helicopter was missing. The helicopter wreckage was subsequently located about 0826 the next morning. Fire department personnel reported fog and mist along the ridgeline during the night.

PERSONNEL INFORMATION

The pilot held a Commercial Pilot certificate with single and multi-engine land airplane, helicopter, instrument airplane, and instrument helicopter ratings. He was issued a Second-Class Airman Medical certificate on July 14, 2007, with a limitation for corrective lenses. The pilot also held a Mechanic certificate with airframe and powerplant ratings.

The pilot's logbook was not available for review by the NTSB. A flight experience summary completed by the accident pilot on January 21, 2008, indicated a total flight time of 3,950 hours, with 2,698 hours of that total in helicopters. He indicated night flight time of 545 hours and instrument flight time of 216 hours. He had accumulated 70 hours of flight time in EC135 helicopters at that time. Duty time records indicated that in the 30-day period prior to the accident, the pilot had flown 17.0 hours. Of that total, 5.8 hours were at night.

The accident pilot was hired by CJ Systems on March 1, 2001. CJ Systems operated the University of Wisconsin Med Flight program at that time. During his tenure as a mechanic, he reportedly also acted as a pilot on maintenance test flights. He transferred to a full-time pilot position on December 1, 2005. Air Methods Corporation purchased CJ Systems in March 2008, and the Madison-based pilots were transferred to Air Methods.

At the time of the transition to Air Methods, the pilots were provided a complete training program under the Air Methods operating certificate. Records indicated that the accident pilot completed basic indoctrination for Air Methods and EC-135 helicopter specific ground training in January 2008. He completed further training related to aeronautical knowledge and EC135P2 helicopter specific knowledge between February 2008 and April 2008. On March 10th and 11th, 2008, the accident pilot completed 3.5 hours flight training in an EC135T2+ helicopter. According to company records, he subsequently passed Part 135 Competency and Line Checks on March 11, 2008. An instrument proficiency check was not completed at that time.

According to company personnel, due to the high training demand resulting from the transition to the Air Methods certificate, all pilots were initially qualified as VFR-only. IFR proficiency checks were planned as recurrent training. As a result the accident pilot was limited to VFR-only operations at the time of the accident. According to a training pilot, the accident pilot was proficient and current for IFR operations under the previous CJ Systems operating certificate.

There were two flights on record to the La Crosse area for the accident pilot between January 1, 2007, and the day of the accident. On March 7, 2008, the pilot had transported a patient from Prairie du Chien Memorial Hospital to Gunderson Lutheran Hospital in La Crosse. The second was the flight prior to the accident flight.

AIRCRAFT INFORMATION

The accident aircraft was a 2007 Eurocopter Deutschland GmbH EC135T2+ helicopter, serial number 0535. The helicopter was powered by two Turbomeca Arrius 2B2 turboshaft engines. The helicopter was certificated under FAA type certificate H88EU, and issued a standard airworthiness certificate on March 14, 2007. The aircraft had accumulated 456.7 hours total flight time as of the day of the accident. Both engines had accumulated the same amount of time. In the 30-day period prior to the accident, the helicopter accumulated 39.8 hours.

The aircraft was maintained under an FAA Approved Aircraft Inspection Program (AAIP). A routine airworthiness check was completed on the day of the accident with no discrepancies noted. According to the operator’s records, the most recent inspection procedure was a 400-Hour inspection completed on March 17, 2008, at 386.1 hours airframe total time.

A 12-Month inspection and a 100-Hour Supplementary inspection were completed on February 26, 2008, at 375.7 hours total airframe time. Altimeter and pitot static system inspections were also completed at that time. During those inspections, a crack was observed in the upper and lower skins of one of the main rotor blades. The blade was subsequently replaced.

The maintenance records noted that on April 16, 2008, the helicopter fell off a tug damaging the landing light and the electrical cannon plug. The damage was subsequently repaired and the aircraft returned to service. With the exception of an inoperative landing light, there were no further discrepancies recorded in the aircraft maintenance records within the 90-day period prior to the accident.

At the time of the accident, the helicopter was equipped with a radar altimeter. It was not equipped, nor was it required to be equipped, with a terrain awareness warning system (TAWS).

METEOROLOGICAL CONDITIONS

The National Weather Service (NWS) Surface Analysis Chart valid at 2200 depicted a low pressure system to the south of the accident site over northern Missouri, with an occluded front extending southward from that low. Several low-pressure troughs extended north and northeastward across Iowa and into northwestern Illinois. A second low-pressure system was located over south-central Minnesota, with a stationary front extending north-northeast through Minnesota and northern Wisconsin.

The NWS Weather Depiction Chart for 2300 depicted an area of instrument flight rules (IFR) conditions over southern Minnesota and portions of Iowa. Surrounding the area of IFR conditions was an area of marginal visual flight rules (MVFR) conditions that included most of Minnesota, Iowa and western Wisconsin and Illinois. Visual flight rules (VFR) conditions extended over central and eastern Wisconsin and Illinois. The intended route of flight, the accident site, and the destination were in the area of MVFR conditions.

IFR conditions are defined as ceilings (broken or overcast cloud layers) below 1,000 feet above ground level (agl) and/or visibilities less than 3 statute miles. MVFR conditions are defined as ceilings between 1,000 feet agl and 3,000 feet agl, and/or visibilities between 3 and 5 miles inclusive. VFR conditions are defined as ceilings above 3,000 feet agl and visibilities greater then 5 miles.

The closest weather reporting facility to the accident site was at LaCrosse Municipal Airport (LSE). LSE was located approximately 5 miles northwest of the accident site. At 2153, the LSE Automated Surface Observations System (ASOS) recorded weather conditions as: Calm winds; 4 miles visibility in light rain and mist; scattered clouds at 1,300 feet agl; overcast clouds at 3,500 feet agl; temperature 10 degrees Celsius; dew point 8 degrees Celsius; and altimeter 29.72 inches of mercury.

At 2253, the LSE ASOS recorded conditions as: Calm winds; 8 miles visibility in light rain; few clouds at 1,400 feet agl; overcast clouds at 5,000 feet agl; temperature 10 degrees Celsius; dew point 8 degrees Celsius; and altimeter 29.70 inches of mercury.

The Area Forecast for southwest Wisconsin issued at 2045 and valid until 0900 the following morning, was for overcast clouds at 6,000 feet agl, with cloud tops to 15,000 feet mean sea level (msl). From 2400, conditions were forecast to be 2,000 feet agl, and visibilities of 3 to 5 miles in light rain and mist. After 0900, the extended outlook consisted of MVFR conditions due to low ceilings and visibilities restricted by rain, with winds over 25 knots.

No Significant Meteorological Information advisories (SIGMETs), Convective SIGMETs, or Severe Weather Forecast Alerts were current over Wisconsin at the time of the accident. However, Airmen's Meteorological Information (AIRMET) Sierra was issued at 2145 and was valid until 0400 the following morning. It warned of possible IFR conditions along the route of flight.

The LSE Terminal Aerodrome Forecast (TAF) issued at 1830 called for: Winds from 130 degrees at 7 knots; visibility greater then 6 miles in light rain; scattered clouds at 3,500 feet agl; and an overcast ceiling at 5,000 feet agl. At 2400, conditions were expected to be: Winds from 020 at 6 knots; visibility 5 miles in light rain and mist; and an overcast cloud ceiling at 2,500 feet agl.

The pilot obtained a preflight weather briefing beginning at 2117 for the route from Prairie du Chein to LaCrosse and back to Madison. The briefer provided a synopsis of current and forecast conditions. He indicated that deteriorating weather conditions were expected after 2200 with IFR conditions possible. The briefer informed the pilot of AIRMET Sierra update 7, issued at 1545 and valid until 2200, warning of IFR conditions southwest of a line from Minneapolis to Bradford, Illinois (BDF). The accident site was located approximately 35 miles northeast of this boundary.

An EMS pilot operating in the area that evening reported that he departed La Crosse at 2024 en route to Arcadia, Wisconsin. He stated that fog was beginning to form on the east side of the Mississippi River. Fog was also beginning to form on the bluffs to the east of his route of flight. He subsequently returned to La Crosse about 2115. He declined at least one additional flight request that evening due to deteriorating weather conditions.

AIRPORT INFORMATION

La Crosse Municipal Airport (KLSE) was located on French Island on the Mississippi River near La Crosse, Wisconsin. The airport elevation was 656 feet. Bluffs rose to approximately 1,200 feet mean sea level on both the east and west sides of the river.

WRECKAGE AND IMPACT INFORMATION

The accident helicopter impacted trees along a wooded ridgeline in a sparsely populated area approximately 4.5 miles southeast of LSE. Tree strikes and main rotor blade fragments were observed at the top of the ridgeline. The right landing skid separated from the airframe at the top of the ridge. The elevation of the ridge in the vicinity of the tree strikes was approximately 1,164 feet. The trees were estimated to be 50 to 60 feet in height, and the tree strikes were approximately 50 to 55 feet above the level of the ridge.

The main wreckage came to rest on a descending hillside, east of the ridgeline. This was on the opposite side of the ridgeline from the departure airport. The helicopter came to rest about 600 feet from the initial tree strikes at the top of the ridgeline, at an elevation of approximately 928 feet. The tail boom and Fenestron (tail rotor) separated from the fuselage. It came to rest about 20 feet from the main wreckage.

The main wreckage consisted of the fuselage (cockpit and cabin areas), the engines, main rotor transmission, rotor mast and rotor blades. The cockpit and cabin areas were completely compromised. The engines exhibited damage consistent with impact forces. The main rotor blades remained attached to the rotor mast; however, the blades were fragmented. The swash plate and pitch change links appeared intact. The transmission exhibited continuity through the assembly when rotated. The flight control servos remained secured to the airframe. The flight control rods between the servos and the cockpit controls were fragmented. The tail boom and Fenestron were fragmented. No anomalies consistent with a pre impact failure were observed.

A teardown inspection of the engines was conducted at the manufacturer's facility under direct supervision of the NTSB. Both engines exhibited damage consistent with impact forces. The compressor and turbine sections of both engines exhibited scoring and scrape markings consistent with rotation at impact. The left engine turbine blades had all sheared at the blade roots. However, examination of the fracture surfaces revealed features consistent with overstress failure. No evidence of pre-existing cracking was observed on any of the blade fractures. No anomalies consistent with pre impact failures were observed during the inspections.

The DC power/engine control panel remained with the instrument panel. However, the instrument panel was dislodged from its normal installed position in the cockpit. The left (ENG 1) main selector switch was in the IDLE position when observed at the accident site. The switch guard was engaged. The right (ENG 2) main switch was in the FLIGHT position when observed at the accident site. Both FADEC control switches were in the ON position. The main engine selector switch detents functioned properly when examined after the accident. The Engine Mode Selector switches on the overhead panel were in the NORM position and the switch guards were engaged.

MEDICAL AND PATHOLOGICAL INFORMATION

An autopsy of the pilot was performed at the Regina Medical Center in Hastings, Minnesota, on May 12, 2008. The report noted multiple traumatic injuries due to a helicopter crash.

A Forensic Toxicology Fatal Accident Report was prepared by the FAA Civil Aeromedical Institute. The results were negative for all substances tested.

TESTS AND RESEARCH

The Digital Engine Control Units (DECUs) were examined by the component manufacturer under supervision of the Federal Aviation Administration. Retained (non-volatile) memory was recovered successfully from each unit. The left and right eng

(c) 2009-2011 Lee C. Baker. For informational purposes only.