# NTSB WPR11CA146: Hiller UH-12E, N236HA, Colusa, CA, February 26, 2011 - Type: NTSB accident investigation - Classification: Accident · No injuries · Data collection · Final report - Date: February 26, 2011, 10:00 local (18:00 UTC) - Place: Colusa, CA - Coordinates: 39.269443, -122.068885 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=39.2694&lon=-122.0689&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Defining event: [Maneuvering-low-alt flying: Settling with power/vortex ring state](https://openairdocs.org/ntsb-events/244) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report June 20, 2011 - Report: Approved by Office Director - NTSB office: Western Pacific Region - Parties: Federal Aviation Administration - NTSB case key (mKey): 78441 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR11CA146 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/78441/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=78441 - Page: https://openairdocs.org/ntsb/WPR11CA146 ## Probable cause The pilot's failure to maintain an adequate airspeed and an inadvertent encounter with settling with power while flying downwind. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Use of equip/info: aircraft control](https://openairdocs.org/ntsb-findings/02063040): Personnel issues › Task performance · Pilot (probable cause); cases with it: [Hiller UH-12E, 7 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md?model=4360122), [All aircraft, 9,295 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md) - [Performance/control parameters: descent rate](https://openairdocs.org/ntsb-findings/01062037): Aircraft › Aircraft oper/perf/capability · Not attained/maintained (probable cause); cases with it: [Hiller UH-12E, 1 case](https://openairdocs.org/ntsb-findings/01062037/cases.md?model=4360122), [All aircraft, 242 cases](https://openairdocs.org/ntsb-findings/01062037/cases.md) - [Performance/control parameters: airspeed](https://openairdocs.org/ntsb-findings/01062010): Aircraft › Aircraft oper/perf/capability · Not attained/maintained (probable cause); cases with it: [Hiller UH-12E, 1 case](https://openairdocs.org/ntsb-findings/01062010/cases.md?model=4360122), [All aircraft, 1,681 cases](https://openairdocs.org/ntsb-findings/01062010/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Maneuvering-low-alt flying: Settling with power/vortex ring state](https://openairdocs.org/ntsb-events/244) (defining event); cases with it: [Hiller UH-12E, 1 case](https://openairdocs.org/ntsb-events/244/sequence.md?model=4360122), [All aircraft, 52 cases](https://openairdocs.org/ntsb-events/244/sequence.md) - [Uncontrolled descent: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Hiller UH-12E, 14 cases](https://openairdocs.org/ntsb-events/470/sequence.md?model=4360122), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) ## Analysis The pilot reported that he and the owner of the helicopter were flying a reconnaissance flight in preparation for a possible frost control flight the following morning. They were attempting to identify potential obstacles in the area. As they were flying slowly over the north edge of an almond orchard he initiated a descent, and slowed the helicopter to just above effective translational lift. He turned southbound and noted a 7- to 10-mile-per-hour tailwind. He reported that the tailwind, coupled with the descent, caused the helicopter to enter a settling with power condition. He stated that due to the close proximity of the trees he was not able to perform a normal recovery of lowering the collective and applying forward cyclic control. The helicopter descended between a row of trees and the main rotor blades struck the trees. The pilot stated that there were no mechanical malfunctions with the helicopter before the accident. ## Factual narrative The pilot reported that when the accident occurred he and the owner of the helicopter were flying a reconnaissance flight in preparation for a possible frost control flight the following morning. They were attempting to identify potential obstacles in the area. The departure was west of the accident site and near an almond orchard. As they were flying slowly over the north edge of the orchard the pilot initiated a descent, as well as slowing the helicopter to just above effective translational lift. He turned southbound and noted a 7- to 10-mile-per-hour (mph) tailwind. The pilot reported that the tailwind, coupled with the descent, caused the helicopter to enter a settling with power condition. He stated that due to the close proximity of the trees he was not able to perform a normal recovery of lowering of the collective and applying forward cyclic control. The helicopter descended between a row of trees and the main rotor blades struck the trees. The pilot stated that there were no mechanical malfunctions with the helicopter before the accident. ## Aircraft - Registration: [N236HA](https://openairdocs.org/aircraft/N236HA), registered now, S/N HA3063, built 1977 (OpenAirDocs) - Reported make and model: HILLER UH-12E - Registry model: [Hiller UH-12E](https://openairdocs.org/model/hiller-uh-12e) (registry code 4360122) (OpenAirDocs) - Registry engine: [Lycoming VO-540 series](https://openairdocs.org/engine/lycoming-vo-540-series) (registry code 41534, reciprocating) (OpenAirDocs) - Category: Helicopter - Serial number: HA3063 - Airframe hours: 7224 - Engines: LYCOMING VO-540 SERIES 310 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Special, Restricted (Special); Standard, Normal - Last inspection: Annual, November 20, 2010, 35 hours before - Departed: Colusa, CA - Destination: Colusa, CA ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 34; injuries: none; commercial; airplane ratings: single-engine land; medical: class 2, without waivers/limitations; last flight review April 8, 2010; seat: center; flight hours: 852 total, 62 in this make and model, 772 as pilot in command, 6 in the last 90 days, 6 in the last 30 days ## Weather - Conditions: Visual (VMC), Day - Wind: 320° at 9 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 39 °F, dew point 30 °F - Altimeter: 29.92 inHg - Observed at: MYV, 25 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 20110226002689A](https://openairdocs.org/incident/20110226002689A), Feb 26, 2011: Hiller UH-12E, Colusa, CA, Substantial damage. During a manuever in an almond orchard, the pilot flew the aircraft from a cross wind direction to a downwind direction during a manuever in an almond orchard,… ## Other investigations on N236HA (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 LAX87DUJ11](https://openairdocs.org/ntsb/LAX87DUJ11), Sep 1, 1987: Hiller UH-12E (N236HA), Scottsdale, AZ, destroyed ## Docket (1 files) The files NTSB released with the investigation on March 21, 2011, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=78441. 286 KB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 286 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40345302&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.