# NTSB WPR11CA398: Bell 47G-4, N948DS, Los Banos, CA, August 21, 2011 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Data collection · Final report - Date: August 21, 2011, 06:55 local (13:55 UTC) - Place: Los Banos, CA - Coordinates: 37.058055, -120.849723 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=37.0581&lon=-120.8497&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Defining event: [Maneuvering-hover: Controlled flight into terr/obj (CFIT)](https://openairdocs.org/ntsb-events/120) - Highest injury: Minor injuries - Injuries: 1 minor - Status: Completed, report October 17, 2011 - Report: Approved by Office Director - NTSB office: Western Pacific Region - Parties: Federal Aviation Administration FSDO - NTSB case key (mKey): 81568 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR11CA398 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/81568/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=81568 - Page: https://openairdocs.org/ntsb/WPR11CA398 ## Probable cause The pilot's failure to maintain clearance from the power poles while maneuvering during low-altitude operations. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Attention/monitoring: task monitoring/vigilance](https://openairdocs.org/ntsb-findings/02021520): Personnel issues › Psychological · Pilot (probable cause); cases with it: [Bell 47G-4, 1 case](https://openairdocs.org/ntsb-findings/02021520/cases.md?model=1181030), [All aircraft, 330 cases](https://openairdocs.org/ntsb-findings/02021520/cases.md) - [Object/animal/substance: pole](https://openairdocs.org/ntsb-findings/03022010): Environmental issues › Physical environment · Response/compensation (probable cause); cases with it: [Bell 47G-4, 1 case](https://openairdocs.org/ntsb-findings/03022010/cases.md?model=1181030), [All aircraft, 142 cases](https://openairdocs.org/ntsb-findings/03022010/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Maneuvering-hover: Controlled flight into terr/obj (CFIT)](https://openairdocs.org/ntsb-events/120) (defining event); cases with it: [Bell 47G-4, 1 case](https://openairdocs.org/ntsb-events/120/sequence.md?model=1181030), [All aircraft, 1,074 cases](https://openairdocs.org/ntsb-events/120/sequence.md) ## Analysis The pilot was performing an agricultural application flight in the helicopter over a cantaloupe field. During the final pass along the field border, he observed bee boxes adjacent to power poles, and he shut off the spray applicator. After passing the boxes, he turned the spray applicator back on; his next recollection was of lying upside down in the field. Examination of the helicopter at the accident site revealed that the main rotor blades struck a set of wooden power poles at the 20-foot-level. The helicopter sustained substantial damage to the main rotor blades and fuselage structure. The pilot reported that he had flown an application flight over the same field a week prior, and was aware of the location of the power poles. The pilot reported no preimpact mechanical malfunctions or failures with the airframe or engine that would have precluded normal operation. ## Factual narrative The pilot was performing an agricultural application flight in the helicopter over a cantaloupe field. During the final pass along the field border, he observed bee boxes adjacent to power poles, and he shut off the spray applicator. After passing the boxes, he turned the spray applicator back on; his next recollection was of lying upside down in the field. Examination of the helicopter at the accident site revealed that the main rotor blades struck a set of wooden power poles at the 20-foot-level. The helicopter sustained substantial damage to the main rotor blades and fuselage structure. The pilot reported that he had flown an application flight over the same field a week prior, and was aware of the location of the power poles. The pilot reported no preimpact mechanical malfunctions or failures with the airframe or engine that would have precluded normal operation. ## Aircraft - Registration: [N948DS](https://openairdocs.org/deregistered/N948DS-2018-01-10), registration cancelled 2018-01-10, S/N 3140 (OpenAirDocs) - Reported make and model: BELL 47G-4 - Registry model: [Bell 47G-4](https://openairdocs.org/model/bell-47g-4) (registry code 1181030) (OpenAirDocs) - Category: Helicopter - Serial number: 3140 - Airframe hours: 8954 - Engines: Allison 250-C20B 420 horsepower turbo shaft - Damage: Substantial damage - Flight: Aerial application, Part 137 - Operator: Double Springs LLC - Registered owner: Schuh Roger J - Airworthiness certificate: Special, Restricted (Special) - Last inspection: Annual, June 1, 2011, 81 hours before - Departed: KLSN, Los Banos, CA - Destination: KLSN, Los Banos, CA - Airport: KLSN, Los Banos ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 40; injuries: minor; commercial, flight instructor; instrument ratings: helicopter; medical: class 2, without waivers/limitations; last flight review August 10, 2010; seat: left; flight hours: 1,643 total, 143 in this make and model, 1,583 as pilot in command, 243 in the last 90 days, 133 in the last 30 days, 5 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 310° at 3 knots - Visibility: 9 statute miles - Lowest ceiling: none - Temperature: 57 °F, dew point 54 °F - Altimeter: 29.89 inHg - Observed at: KMCE, 21 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 20110821017499A](https://openairdocs.org/incident/20110821017499A), Aug 21, 2011: Bell 47G-4, Los Banos, CA, Substantial damage. Halfway through a cleanup swath run of the first flight of the day the pilot hit a power pole with the rotor blades. The pilot had previously sprayed the field… ## Docket (3 files) The files NTSB released with the investigation on September 15, 2011, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=81568. 784 KB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 451 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40353684&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - Photo 1: Helicopter and Power Pole (item 2, .PDF, 120 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40353685&FileExtension=.PDF&FileName=Photo%201%3A%20Helicopter%20and%20Power%20Pole-Master.PDF - Photo 2: Helicopter (item 3, .PDF, 214 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40353686&FileExtension=.PDF&FileName=Photo%202%3A%20Helicopter-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.