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N135UW accident description

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Crash location 43.841944°N, 91.165556°W
Nearest city La Crosse, WI
43.801356°N, 91.239581°W
4.6 miles away
Tail number N135UW
Accident date 10 May 2008
Aircraft type Eurocopter Deutschland Gmbh Ec 135 T2+
Additional details: None

NTSB Factual Report

HISTORY OF FLIGHT

On May 10, 2008, about 2237 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. A flight plan had not been filed with the Federal Aviation Administration (FAA). Night visual meteorological conditions prevailed in the vicinity of the accident site. The pilot, physician and flight nurse sustained fatal injuries. The flight departed the 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 (OCC). Flight progress was automatically updated approximately every three minutes and tracked by the operator’s OCC. According to 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 helicopter noted that when it departed, it lifted off vertically and proceeded east-southeast. Regarding the weather conditions, he added that the visibility was “fair”, with a “low ceiling” 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 a Medlink helicopter. He reported that it seemed to be "traveling at a high rate of speed, and was flying low." He recalled thinking that it was not going to clear the bluffs.

A second witness 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.

PERSONNEL INFORMATION

The pilot, age 39, 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 obtained by the NTSB. The operator reported the accident pilot’s flight experience as 4,003 hours total flight time, with 2,741 hours in rotorcraft, and 121 hours in EC135 helicopters. The pilot’s night flight time was 545 hours and instrument flight time was 216 hours. Within the 90-day period prior to the accident, the pilot had flown 49 hours in EC135 helicopters. 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 operator initially noted that the pilot had accumulated 2.7 hours of actual instrument flight time during the previous 12 months. However, they subsequently advised that the accident pilot had accumulated 2.5 hours of instrument flight time between July 2005 and March 2008. During the 12-month period preceding the accident, the pilot acquired a total of 0.4 hours actual instrument flight time; all of which was during a single flight on May 17, 2007.

The accident pilot was hired by CJ Systems on March 1, 2001, as a mechanic. 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 training under the Air Methods operating certificate. Training 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 EC 135 P2 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 EC 135 T2+ helicopter. According to company records, he passed Part 135 Competency and Line Checks on March 11, 2008. An instrument proficiency check was not completed at that time. As a result, the accident pilot was limited to visual flight rules (VFR) operations under the Air Methods certificate at the time of the accident.

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 on the evening of the accident.

AIRCRAFT INFORMATION

The accident helicopter was a 2007 Eurocopter Deutschland GmbH EC 135 T2+ helicopter, serial number 0535. It 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. It had accumulated 456.7 hours total flight time as of the day of the accident. Both engines had accumulated the same amount of time as the airframe. In the 30-day period prior to the accident, the helicopter accumulated 39.8 hours.

The helicopter 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 replaced at that time.

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 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. The records noted that landing light bulb had been replaced prior to the day of 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 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. 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 than 5 miles.

The closest weather reporting facility to the accident site was at 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 than 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 La Crosse 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 west 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.

Fire department personnel reported that there was fog and mist along the ridgeline overnight during the search operations.

Sunset occurred at 2019, with civil twilight ending at 2052. The sun was more than 15 degrees below the horizon about the time of the accident. The moon was about 30 degrees above the horizon at the time of the accident. It was in a waxing crescent phase with approximately 39 percent of the moon's disk illuminated. The moon set at 0154 on May 11th, about 3 hours after the accident.

AIRPORT INFORMATION

La Crosse Municipal Airport (LSE) was located on French Island on the Mississippi River near La Crosse, Wisconsin. The airport elevation was 655 feet. Ridgelines rose to approximately 1,200 feet mean sea level on both the east and west sides of the river. The cities of La Crosse and Onalaska were located between the river and the ridgeline east of the airport. The ridges were sparsely populated.

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 (GPS altitude/elevation). The trees were estimated to be 50 to 60 feet tall. The tree strikes were located near the top of the trees; approximately 50 to 55 feet above ground level.

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 (GPS altitude/elevation). 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, main rotor mast and main rotor blade roots. The cockpit and cabin areas were completely compromised. The altimeter setting was 29.71 inches when observed at the accident site. The engines remained with the airframe; however, the engine housings were dented and deformed consistent with impact damage. The main rotor blade roots remained attached to the rotor mast; however, the blades were fragmented. The swash plate and pitch change links were observed intact. The transmission exhibited continuity through the assembly when rotated. The left engine drive shaft was bent approximately 20 degrees at the aft end. The right engine drive shaft appeared intact. Both drive shafts were separated from the engine drive splines when observed at the accident site. 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. A section of the Fenestron drive shaft approximately 4 feet in length was separated near the forward end of the tailboom and forward of the Fenestron shroud.

A teardown inspection of the engines was conducted at the manufacturer's facility under direct supervision of the NTSB. The air inlets of both engine contained debris, which appeared consistent with dirt and wood fragments. The compressor and turbine sections of both engines exhibited scoring and scrape markings consistent with rotation at impact. The left engine power turbine blades had all sheared off at the blade roots. Examination of the fracture surfaces revealed features consistent with overload failure. No evidence of pre-existing cracking was observed on any of the blade fractures. The right engine power turbine blades remained intact.

The DC power/engine control panel remained with the instrument panel. However, the instrument panel was dislodged from its normal position in the cockpit. The left (ENG 1) main selector switch was in the IDLE position when observed at the accident site. The right (ENG 2) main switch was in

NTSB Probable Cause

The pilot’s failure to maintain clearance from trees along the top of a ridgeline due to inadequate preflight planning, insufficient altitude, and the lack of a helicopter terrain awareness and warning system.

Member Sumwalt did not approve this brief and probable cause. Member Sumwalt filed a dissenting statement that can be found in the public docket for this accident.

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