# NTSB WPR10CA164: Eurocopter AS 350 B3, N4282, Parker, AZ, March 16, 2010 - Type: NTSB accident investigation - Classification: Accident · No injuries · Data collection · Final report - Date: March 16, 2010, 09:30 local (16:30 UTC) - Place: Parker, AZ - Coordinates: 34.136665, -114.285552 - Nearby events: https://openairdocs.org/map.md?lat=34.1367&lon=-114.2856&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Defining event: [Maneuvering-hover: Miscellaneous/other](https://openairdocs.org/ntsb-events/900) - Highest injury: No injuries - Injuries: 3 uninjured - Status: Completed, report July 1, 2010 - Report: Approved by Office Director - NTSB office: Western Pacific Region - Parties: FAA FSDO - NTSB case key (mKey): 75545 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR10CA164 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/75545/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=75545 - Page: https://openairdocs.org/ntsb/WPR10CA164 ## Probable cause The mechanics' failure to account for all the tools following a maintenance procedure and the pilot's failure to perform a preflight check before a maintenance test flight. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Maintenance: scheduled/routine maintenance](https://openairdocs.org/ntsb-findings/02062010): Personnel issues › Task performance · Maintenance personnel (probable cause); cases with it: [Eurocopter AS 350 B3, 2 cases](https://openairdocs.org/ntsb-findings/02062010/cases.md?model=8680954), [All aircraft, 320 cases](https://openairdocs.org/ntsb-findings/02062010/cases.md) - [Inspection: preflight inspection](https://openairdocs.org/ntsb-findings/02061510): Personnel issues › Task performance · Pilot (probable cause); cases with it: [Eurocopter AS 350 B3, 2 cases](https://openairdocs.org/ntsb-findings/02061510/cases.md?model=8680954), [All aircraft, 551 cases](https://openairdocs.org/ntsb-findings/02061510/cases.md) - [Object/animal/substance: debris/dirt/foreign object](https://openairdocs.org/ntsb-findings/03022055): Environmental issues › Physical environment · Effect on equipment; cases with it: [Eurocopter AS 350 B3, 1 case](https://openairdocs.org/ntsb-findings/03022055/cases.md?model=8680954), [All aircraft, 101 cases](https://openairdocs.org/ntsb-findings/03022055/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Prior to flight: Aircraft maintenance event](https://openairdocs.org/ntsb-events/040); cases with it: [Eurocopter AS 350 B3, 3 cases](https://openairdocs.org/ntsb-events/040/sequence.md?model=8680954), [All aircraft, 484 cases](https://openairdocs.org/ntsb-events/040/sequence.md) - [Prior to flight: Aircraft inspection event](https://openairdocs.org/ntsb-events/050); cases with it: [Eurocopter AS 350 B3, 2 cases](https://openairdocs.org/ntsb-events/050/sequence.md?model=8680954), [All aircraft, 229 cases](https://openairdocs.org/ntsb-events/050/sequence.md) - [Maneuvering-hover: Miscellaneous/other](https://openairdocs.org/ntsb-events/900) (defining event); cases with it: [Eurocopter AS 350 B3, 6 cases](https://openairdocs.org/ntsb-events/900/sequence.md?model=8680954), [All aircraft, 1,556 cases](https://openairdocs.org/ntsb-events/900/sequence.md) ## Analysis The pilot of the helicopter told the lead mechanic that the main rotor blade needed to be balanced. Two mechanics showed up on the morning of the accident and installed the balancing equipment. A test flight was flown. The two men performed the necessary work, which required a second adjustable wrench on the top of the rotor head to hold the bolt while the nut below was removed and later torqued back on. When the work was finished, the men gathered their tools. The pilot asked the lead mechanic if they had gathered all their tools and the mechanic replied "yes." The three men got on the helicopter for a test hover to check their work. As the main rotor speed reach 100 percent, the three occupants heard a "bang." As the helicopter hovered, the two mechanics thought the balancing equipment readings were worse than the first flight, and the vibrations in the aircraft had increased. The pilot landed the helicopter so that the mechanics could make additional adjustments. The mechanics discovered that they were missing the adjustable wrench that had been used on the top of the main rotor head. Postaccident examination revealed that one main rotor blade, the tail boom, and the lower vertical stabilizer had received damage from the unaccounted for wrench. ## Factual narrative The pilot of the helicopter told the lead mechanic that the main rotor blade needed to be balanced. Two mechanics showed up on the morning of the accident and installed the balancing equipment. A test flight was flown. The two men performed the necessary work, which required a second adjustable wrench on the top of the rotor head to hold the bolt while the nut below was removed and later torqued back on. When the work was finished, the men gathered their tools. The pilot asked the lead mechanic if they had gathered all their tools and the mechanic replied "yes." The three men got on the helicopter for a test hover to check their work. As the main rotor speed reach 100 percent, the three occupants heard a "bang." As the helicopter hovered, the two mechanics thought the balancing equipment readings were worse than the first flight, and the vibrations in the aircraft had increased. The pilot landed the helicopter so the mechanics could make additional adjustments. The mechanics discovered that they were missing the adjustable wrench that had been used on the top of the main rotor head. Post accident examination revealed that one main rotor blade, the tail boom, and the lower vertical stabilizer had received damage from the unaccounted for wrench. ## Aircraft - Registration: [N4282](https://openairdocs.org/aircraft/N4282), registered now, S/N 4282, built 2007 (OpenAirDocs) - Reported make and model: EUROCOPTER AS 350 B3 - Registry model: [Eurocopter AS 350 B3](https://openairdocs.org/model/eurocopter-as-350-b3) (registry code 8680954) (OpenAirDocs) - Registry engine: [Turbomeca ARRIEL-2B1](https://openairdocs.org/engine/turbomeca-arriel-2b1) (registry code 60056, turbo-shaft) (OpenAirDocs) - Category: Helicopter - Serial number: 4282 - Airframe hours: 819 - Engines: TURBOMECA ARRIEL 2B1 747 horsepower turbo shaft - Damage: Substantial damage - Flight: Other work use, Part 91 - Operator: Omniflight Helicopters inc. - Registered owner: Cfs Air LLC - Airworthiness certificate: Standard, Normal - Last inspection: AAIP, February 3, 2010 - Departed: AZ47, Parker, AZ - Destination: AZ47, Parker, AZ - Airport: AZ47, Lapaz Regional Hospital Helpt ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 52; injuries: none; flight instructor, commercial; instrument ratings: helicopter; medical: class 2, with waivers/limitations; last flight review March 21, 2009; seat: right; flight hours: 3,900 total, 1,354 in this make and model, 28 in the last 90 days, 1 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 50° at 5 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 70 °F, dew point 39 °F - Altimeter: 30.30 inHg - Observed at: BLH ## 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 20100316032849A](https://openairdocs.org/incident/20100316032849A), Mar 16, 2010: Eurocopter AS 350 B3, Parker, AZ, Substantial damage. On 3-16-2010 omniflight helicopter N4282, s/n 4282 located at la paz regional Hospital, Parker, AZ sustained damage to one main rotor blade, right side of… ## Docket (1 files) The files NTSB released with the investigation on April 14, 2010, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=75545. 1.4 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 1.4 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40328258&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.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.