# NTSB ANC15LA076: Airbus AS-350, N504WD, Hamilton, MT, May 4, 2015 - Type: NTSB accident investigation - Classification: Accident · No injuries · Class 3 · Limited · Final report - Date: May 4, 2015, 10:45 local (16:45 UTC) - Place: Hamilton, MT - Coordinates: 46.251667, -114.12555 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=46.2517&lon=-114.1256&mi=10 - Phase of flight: [Emergency descent](https://openairdocs.org/ntsb-phases/600) (OpenAirDocs' grouping) - Defining event: [Autorotation: Hard landing](https://openairdocs.org/ntsb-events/092) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Alaska Regional Office - Parties: Bureau d'Enquetes et d'Analyses, FAA Helena FSDO - NTSB case key (mKey): 91217 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC15LA076 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/91217/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=91217 - Page: https://openairdocs.org/ntsb/ANC15LA076 ## Probable cause The pilot's excessive collective application during an autorotation. Contributing to the accident was the flight instructor's inadequate supervision of the training flight. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Rotorcraft flight control: main rotor control](https://openairdocs.org/ntsb-findings/01046710): Aircraft › Aircraft propeller/rotor · Incorrect use/operation (probable cause); cases with it: [All aircraft, 28 cases](https://openairdocs.org/ntsb-findings/01046710/cases.md) - [Use of equip/info: use of equip/system](https://openairdocs.org/ntsb-findings/02063015): Personnel issues › Task performance · Pilot (probable cause); cases with it: [All aircraft, 1,391 cases](https://openairdocs.org/ntsb-findings/02063015/cases.md) - [Attention/monitoring: monitoring other person](https://openairdocs.org/ntsb-findings/02021535): Personnel issues › Psychological · Instructor/check pilot (probable cause); cases with it: [All aircraft, 200 cases](https://openairdocs.org/ntsb-findings/02021535/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Autorotation: Attempted remediation/recovery](https://openairdocs.org/ntsb-events/060); cases with it: [All aircraft, 1,422 cases](https://openairdocs.org/ntsb-events/060/sequence.md) - [Autorotation: Hard landing](https://openairdocs.org/ntsb-events/092) (defining event); cases with it: [All aircraft, 2,102 cases](https://openairdocs.org/ntsb-events/092/sequence.md) ## Analysis The flight instructor, in the left seat reported that he was providing flight instruction to the commercial pilot, in the right seat, which included a series of hovering autorotations. According to the instructor, as the commercial pilot hovered the helicopter about 3 or 4 ft above the ground, the instructor initiated the hovering autorotation by reducing the floor-mounted throttle (fuel flow control lever) to about 70% N1, and the helicopter descended to about 1 ft above the ground. As the commercial pilot tried to cushion the touchdown, he inadvertently applied too much collective pitch, and the helicopter ballooned to a higher altitude. During the second descent, the main rotor rpm continued to decay, and the helicopter’s skids struck the ground. The instructor did not take control of the helicopter during this sequence. A postflight inspection revealed substantial damage to the tailboom. ## Factual narrative On May 4, 2015, about 1045 mountain daylight time, an Airbus AS-350 BA helicopter, N504WD, sustained substantial damage as a result of a hard landing during a practice hovering autorotation at the Ravalli County Airport in Hamilton, Montana. The helicopter was being operated as a visual flight rules local area proficiency/instructional flight under Title 14 Code of Federal Regulations Part 91 when the accident occurred. The helicopter was registered to Hat Creek Helicopters LLC, Hamilton, Montana. The flight instructor and commercial pilot were not injured. Visual meteorological conditions prevailed at the time of the accident and no flight plan was filed. The flight originated from the Ravalli County Airport. In the flight instructor’s written statement, dated June 1, 2015, he reported that the purpose of the flight was to provide flight instruction to the commercial pilot, which included hovering autorotations. The flight instructor related that before starting the first hovering autorotation maneuver, he had the pilot hover the helicopter about 3 or 4 ft above the ground. The flight instructor then initiated the hovering autorotation by reducing the floor-mounted throttle (fuel flow control lever) to about 70% N1, and the helicopter descended to about 1 ft above the ground. He said that as the pilot tried to cushion the touchdown, he inadvertently applied too much collective pitch, and the helicopter ballooned to a higher altitude. The main rotor rpm decayed as the helicopter descended, and the skids subsequently struck the ground hard. The flight instructor characterized the landing as “firm” but both pilots were unaware of any damage sustained to the helicopter. The flight instructor reported that they performed several additional training maneuvers and then landed without further incident. A postflight inspection revealed substantial damage to the tailboom. The flight instructor reported that it was difficult to control the throttle due to its location, mounted on the pedestal between the front seats, necessitating the release of either the cyclic or collective control to manipulate the throttle. Further, not having an idle detent made the pilot/instructor vulnerable to inadvertently shutting down the engine while trying to manipulate the throttle for training or emergency purposes. The flight instructor verified that there were no preimpact mechanical failures or malfunctions with the airframe or engine that would have precluded normal operation. ## Aircraft - Registration: N504WD (not matched to a registry record) - Reported make and model: AIRBUS AS-350 (BA) - Category: Helicopter - Serial number: 1800 - Year built: 1984 - Airframe hours: 5696.9 - Engines: Turbomeca Arriel 1B 440 horsepower turbo shaft - Damage: Substantial damage - Flight: Instructional, Part 91 - Airworthiness certificate: Standard, Normal - Last inspection: AAIP, February 10, 2015, 31 hours before - Departed: 6S5, HAMILTON, MT - Destination: 6S5, HAMILTON, MT - Airport: 6S5, Ravalli County - Equipment: None ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 35; injuries: none; commercial, private; airplane ratings: single-engine sea, single-engine land; medical: class 2, without waivers/limitations; last flight review August 19, 2014; seat: right; restraint: 4-point; flight hours: 570.5 total, 201.6 in this make and model, 416.2 as pilot in command, 27 in the last 90 days - Flight instructor; age 66; injuries: none; flight instructor, flight engineer, airline transport; airplane ratings: multi-engine land; instrument ratings: helicopter, airplane; medical: class 2, with waivers/limitations; last flight review July 10, 2014; seat: left; restraint: 4-point; flight hours: 18,000 total, 500 in this make and model, 10,000 as pilot in command, 107 in the last 90 days, 24 in the last 30 days, 0.3 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: calm - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 52 °F, dew point 28 °F - Altimeter: 29.95 inHg - Observed at: KMSO, 40 nm away ## 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 20150504007049A](https://openairdocs.org/incident/20150504007049A), May 4, 2015: Eurocopter AS 350 BA, Hamilton, MT, Substantial damage. During power off auto rotation training, the rotorcraft experienced a hard landing resulting in significant damage to the tailboom aft of the fuselage/tailboom… ## Docket (14 files) The files NTSB released with the investigation on May 9, 2017, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=91217. 5.4 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 837 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40445815&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.PDF - Accident Photographs (Courtesy of Operator) (item 2, .PDF, 4 photos, 601 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40445816&FileExtension=.PDF&FileName=Accident%20Photographs%20(Courtesy%20of%20Operator)-Master.PDF - Flight Instructor Statement 1 (item 3, .PDF, 68 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40445818&FileExtension=.PDF&FileName=Flight%20Instructor%20Statement%201-Master.PDF - Flight Instructor Statement 2 (item 4, .PDF, 64 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40445819&FileExtension=.PDF&FileName=Flight%20Instructor%20Statement%202-Master.PDF - Flight Instructor Statement 3 (item 5, .PDF, 174 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40445820&FileExtension=.PDF&FileName=Flight%20Instructor%20Statement%203-Master.PDF - Pilot Statement 1 (item 6, .PDF, 67 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40445821&FileExtension=.PDF&FileName=Pilot%20Statement%201-Master.PDF - Pilot Statement 2 (item 7, .PDF, 64 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40445822&FileExtension=.PDF&FileName=Pilot%20Statement%202-Master.PDF - FAA Inspector Statement (item 8, .PDF, 190 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40445823&FileExtension=.PDF&FileName=FAA%20Inspector%20Statement-Master.PDF - FAA safo 16006 (item 9, .PDF, 54 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40445824&FileExtension=.PDF&FileName=FAA%20SAFO%2016006-Master.PDF - Airbus Safety Information Notice 2896-S-00 (item 10, .PDF, 70 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40445825&FileExtension=.PDF&FileName=Airbus%20Safety%20Information%20Notice%202896-S-00-Master.PDF - NTSB Safety Recommendations A-06-36 to A-06-38 (item 11, .PDF, 2.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40445826&FileExtension=.PDF&FileName=NTSB%20Safety%20Recommendations%20A-06-36%20to%20A-06-38-Master.PDF - NTSB Safety Recommendations A-10-129 to A-10-130 (item 12, .PDF, 506 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40445827&FileExtension=.PDF&FileName=NTSB%20Safety%20Recommendations%20A-10-129%20to%20A-10-130-Master.PDF - NTSB Safety Recommendation A-10-131 (item 13, .PDF, 489 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40445828&FileExtension=.PDF&FileName=NTSB%20Safety%20Recommendation%20A-10-131-Master.PDF - FAA Form 8020-23 Excerpt (item 14, .PDF, 137 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40445829&FileExtension=.PDF&FileName=FAA%20Form%208020-23%20Excerpt-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.