# NTSB DFW06LA057: Agusta A109E, N142CF, Fort Worth, TX, January 19, 2006 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: January 19, 2006, 15:15 local (21:15 UTC) - Place: Fort Worth, TX - Coordinates: 32.818611, -97.357223 - Nearby events: https://openairdocs.org/map.md?lat=32.8186&lon=-97.3572&mi=10 - Phase of flight: [Taxi](https://openairdocs.org/ntsb-phases/250) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report August 29, 2006 - Report: Approved by Office Director - Parties: CareFlight - Director of Operations, Agusta Westland, Federal Aviation Administration, CareFlight - Director of Maintenance - NTSB case key (mKey): 63130 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DFW06LA057 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/63130/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=63130 - Page: https://openairdocs.org/ntsb/DFW06LA057 ## Probable cause The pilot's inadvertent encounter with ground resonance which resulted in the destruction of the helicopter. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of control - on ground/water, taxi - ground resonance - inadvertent, pilot in command (cause) ## Analysis The 6,500-hour commercial helicopter rated pilot inadvertently encountered ground resonance while ground taxiing. The pilot performed a normal startup and prepared for ground taxi. He moved the helicopter forward and then started the helicopter in a 90-degree ground taxi turn at 30-degree intervals. He pushed on the toe brakes to stop the helicopter to give right of way to an aircraft taxiing down the taxiway. At this time the helicopter started to shake and bounce. Before the pilot could get the aircraft shutdown, the aircraft executed an uncommanded 90-degree turn to the left. The helicopter's main rotors and transmission assembly separated from the airframe. The wind at the time of the accident was reported to be from 170 degrees at 17 knots, gusting to 23 knots. ## Factual narrative On January 19, 2005, approximately 1515 central standard time, a twin-engine Augusta A109E turbo-shaft helicopter, N142CF, registered to North Central Texas Services of Grand Prairie, Texas, and operated by CareFlight of Grand Prairie, Texas, was substantially damaged while taxiing at the Fort Worth Meacham International Airport (FTW) near Fort Worth, Texas. The commercial pilot, sole occupant of the aircraft, was not injured. Visual meteorological conditions prevailed, and a company visual flight rules flight plan was filed for the repositioning flight conducted under 14 Code of Federal Regulations Part 91. The 6,500-hour pilot reported in the Pilot/Operator Aircraft Accident Report (NTSB Form 6120.1) that he performed a "normal startup and prepared for ground taxi. I started the aircraft forward then started the aircraft in a 90-degree ground taxi turn in 30-degree intervals. I pushed on the toe brakes to stop the aircraft to give right away for aircraft taxiing down the taxiway. At this time the aircraft started to shake. Before I could get the aircraft shutdown, the aircraft did a 90 degree turn to the left." According to several witnesses, the helicopter was taxiing to the south and then stopped just as a fixed wing airplane was taxiing to the east into the ramp area for a fixed base operator. The helicopter began to shake and bounce very rapidly from side to side as if it were trying to roll about its longitudinal axis. The helicopter then turned 90-degrees to its left followed by the separation of the rotor and mast components and part of the upper fueslage, from the airframe. One of the witnesses stated that "the whole event probably took no more than 5 to 10 seconds." Examination of the helicopter by a Federal Aviation Administration (FAA) inspector, who responded to the accident site, revealed that the helicopters main rotors and transmission assembly separated from the airframe. The main rotor actuator attachment fitting had separated into three pieces ( a left leg, right leg and fitting). All three pieces were retained for further examination. On March 22, 2006, at the NTSB's Material Laboratory in Washington, D.C., an examination of the main rotor actuator attachment fitting was conducted by an NTSB metallurgist and representatives from the FAA, Agusta, and CareFlight. A bench binocular microscope examination of the fracture face from the left leg revealed that the fracture was largely on a flat plane and had two distinct fracture regions. One of the regions had a woody, matte appearance typical of an overstress fracture region. The remainder of the fracture was heavily damaged from contact with the mating fracture surface and contained fracture lines oriented primarily in the forward/aft direction. A scanning electron microscope (SEM) examination of the fracture face on the left leg revealed the "damaged region" contained mechanical damage that resulted from shear stress. The damaged portion of the fracture at one isolated area showed a feature that appeared similar to striations, but this striation-like feature was not found in other areas of the fracture or on the fracture face of the other separated leg. The striation-like feature also resembled the highly textured fracture features in the overstress region. The fracture face did not contain any other features that are typical of a fatigue crack (such as radial marks that point to a fatigue origin, crack arrest bands, thumbnail shaped crack regions, or a terminus of a fatigue region). During the SEM examination, areas of undamaged features were found near the top of the fracture in the left leg. These areas contained a highly textured surface with features that were oriented parallel to the length of the leg and ductile dimple features typical of overstress separation. The right leg portion showed fracture features that were similar to those found on the left leg. At 1453, the automated surface observing system (ASOS) at FTW reported the wind from 170 degrees at 17 knots, gusting to 23 knots, visibility 10 statute miles, clear sky, temperature 73 degrees Fahrenheit, dew point 44 degrees Fahrenheit and a barometric pressure of 29.87 inches of Mercury. ## Aircraft - Registration: [N142CF](https://openairdocs.org/deregistered/N142CF-2007-07-28), registration cancelled 2007-07-28, S/N 11141, built 2002 (OpenAirDocs) - Reported make and model: Agusta A109E - Registry model: [Agusta A109E](https://openairdocs.org/model/agusta-a109e) (registry code 0260101) (OpenAirDocs) - Registry engine: [Pratt & Whitney Canada PW206C](https://openairdocs.org/engine/pratt-whitney-canada-pw206c) (registry code 52160, turbo-shaft) (OpenAirDocs) - Category: Helicopter - Serial number: 11141 - Airframe hours: 1766 - Engines: Pratt & Whitney PW-206C 950 horsepower turbo shaft; Pratt & Whitney PW-206C 950 horsepower turbo shaft - Damage: Substantial damage - Flight: Positioning, Part 91 - Registered owner: North Central Texas Services - Airworthiness certificate: Standard, Normal - Last inspection: AAIP, January 1, 2006 - Departed: KFTW, Fort Worth, TX - Destination: KGPM, Grand Prairie, TX - Flight plan: Company VFR - Airport: KFTW, Ft Worth International Airport ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 36; injuries: none; commercial; airplane ratings: single-engine land; instrument ratings: helicopter; medical: class 2, without waivers/limitations; last flight review October 1, 2005; seat: right; flight hours: 6,500 total, 250 in this make and model, 5,500 as pilot in command, 40 in the last 90 days, 15 in the last 30 days, 1 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 170° at 17 knots, gusting 23 - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 73 °F, dew point 45 °F - Altimeter: 29.87 inHg - Observed at: KFTW ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Accident 20060119001589A](https://openairdocs.org/incident/20060119001589A), Jan 19, 2006: Agusta A109A, Fort Worth, TX, Destroyed. (-23) Pilot was turning rotorcraft to a heading of 180 for taxi to echo taxiway and saw an aircraft on echo taxiway. Pilot stopped the rotorcraft at which time… ## Other investigations on N142CF (1) From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. - [NTSB FTW03LA038](https://openairdocs.org/ntsb/FTW03LA038), Nov 8, 2002: Agusta A109E (N142CF), Fort Worth, TX, substantial damage. Probable cause: The pilot's attempted running takeoff with the power controls in the improper position. ## Docket (3 files) The files NTSB released with the investigation on May 15, 2006, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=63130. 7.2 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 559 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40260583&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - Witness Statments (item 2, .PDF, 395 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40260586&FileExtension=.PDF&FileName=Witness%20Statments-Redacted.PDF - Materials Laboratory Factual Report 06-032 (item 3, .PDF, 6.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40260808&FileExtension=.PDF&FileName=Materials%20Laboratory%20Factual%20Report%2006-032-Master.PDF From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.