# NTSB WPR16LA099: Bell 47G 5, N6288N, San Ardo, CA, April 29, 2016 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Class 3 · Limited · Final report - Date: April 29, 2016, 07:15 local (14:15 UTC) - Place: San Ardo, CA - Coordinates: 36.007221, -120.87889 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=36.0072&lon=-120.8789&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Defining event: [Maneuvering-low-alt flying: Loss of control in flight](https://openairdocs.org/ntsb-events/240) - Highest injury: Minor injuries - Injuries: 1 minor - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Western Pacific Region - Parties: Federal Aviation Administration - NTSB case key (mKey): 93102 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR16LA099 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/93102/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=93102 - Page: https://openairdocs.org/ntsb/WPR16LA099 ## Probable cause The failure of the pin in the outboard end of the lateral flight control torque tube. ## 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 · Fatigue/wear/corrosion (probable cause); cases with it: [Bell 47G-5, 1 case](https://openairdocs.org/ntsb-findings/01046710/cases.md?model=1181032), [All aircraft, 28 cases](https://openairdocs.org/ntsb-findings/01046710/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: Loss of control in flight](https://openairdocs.org/ntsb-events/240) (defining event); cases with it: [Bell 47G-5, 4 cases](https://openairdocs.org/ntsb-events/240/sequence.md?model=1181032), [All aircraft, 5,002 cases](https://openairdocs.org/ntsb-events/240/sequence.md) - [Maneuvering-low-alt flying: Flight control sys malf/fail](https://openairdocs.org/ntsb-events/333); cases with it: [Bell 47G-5, 1 case](https://openairdocs.org/ntsb-events/333/sequence.md?model=1181032), [All aircraft, 410 cases](https://openairdocs.org/ntsb-events/333/sequence.md) ## Analysis While performing an agricultural flight, the pilot of the helicopter heard a loud noise followed by a vibration in the flight controls, and the helicopter began to roll. He noted that the cyclic was stiffer than normal, and his control inputs produced a delayed response from the helicopter. The pilot was able to return the helicopter to level flight and attempted a run-on landing; however, the helicopter began a roll to the left, which he was not able to correct before the main rotor blades impacted the ground and the helicopter rolled onto its side, resulting in substantial damage. Postaccident examination revealed that the pin for the outboard end torque tube, which controlled lateral movement of the swashplate, was fractured. ## Factual narrative On April 20, 2016, about 0715 Pacific daylight time, a Bell 47G-5, N6288N, was substantially damaged when it was involved in an accident near San Ardo, California. The pilot received minor injuries. The helicopter was operated as a Title 14 Code of Federal Regulations (CFR) Part 137 agricultural flight. The pilot stated that he had sprayed five fields that day with no anomalies. After performing a reconnaissance of the sixth field, the pilot was descending the helicopter for a spray pass when the helicopter made a loud noise immediately followed by a vibration. The pilot stated that the helicopter was level but started to roll to one side. He moved the cyclic laterally to correct, but the cyclic was stiffer than normal. The pilot stated that, although the helicopter responded to his inputs, there was a lag in its response that resulted in an overcorrection. He went through two cycles of oscillations before the helicopter was level. He subsequently attempted a run-on landing; however, the helicopter rolled to the left and he was not able to correct with right cyclic before the main rotor blades impacted the ground. The helicopter came to rest on its left side. A Federal Aviation Administration (FAA) inspector examined the wreckage and identified that the pin of the outboard end torque tube that controlled lateral movement of the swashplate had fractured. The control tube and the upper threaded end were attached to the clevis, which attached to the swashplate and controlled the forward and aft cyclic. The lower end of the control tube remained attached and the upper end had separated. ## Aircraft - Registration: [N6288N](https://openairdocs.org/aircraft/N6288N), registered now, S/N 7888, built 1968 (OpenAirDocs) - Reported make and model: BELL 47G 5 - Registry model: [Bell 47G-5](https://openairdocs.org/model/bell-47g-5) (registry code 1181032) (OpenAirDocs) - Registry engine: [Lycoming VO-435 series](https://openairdocs.org/engine/lycoming-vo-435-series) (registry code 41525, reciprocating) (OpenAirDocs) - Category: Helicopter - Serial number: 7888 - Year built: 1968 - Airframe hours: 7013 - Engines: LYCOMING VO-435-B1A 265 horsepower reciprocating - Damage: Substantial damage - Flight: Aerial application, Part 137 - Operator: Wilbur-Ellis Co - Registered owner: Wilbur-Ellis Co - Airworthiness certificate: Special, Restricted (Special); Standard, Normal - Last inspection: 100 hour, April 21, 2016, 21 hours before - Departed: San Ardo, CA - Destination: San Ardo, CA - Equipment: None ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 39; injuries: minor; commercial, airline transport; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane, helicopter; medical: class 2, without waivers/limitations; last flight review December 29, 2015; seat: left; restraint: 4-point; flight hours: 8,425 total, 5,000 in this make and model, 175 in the last 90 days, 85 in the last 30 days, 5 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 320° at 6 knots - Visibility: 10 statute miles - Lowest ceiling: 400 ft overcast - Temperature: 48 °F, dew point 46 °F - Altimeter: 30.03 inHg - Observed at: KPRB, 24 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 20160429005499A](https://openairdocs.org/incident/20160429005499A), Apr 29, 2016: Bell 47G-5, San Ardo, CA, Substantial damage. On April 29, 2016, near San Ardo, CA, N6288N, a Bell 47G-5, spraying a field with pesticide, entered a left turn and leveled off. The aircraft started shaking… ## Other investigations on N6288N (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 LAX87DVM03](https://openairdocs.org/ntsb/LAX87DVM03), Jun 28, 1987: Bell 47G-5 (N6288N), Salinas, CA, substantial damage ## Docket (3 files) The files NTSB released with the investigation on February 4, 2021, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=93102. 6.9 MB in all. - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 10 pages, 4.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11844971&FileExtension=pdf&FileName=6120_Redacted-Rel.pdf - Summary of findings (FAA) (item 2, PDF, 1 page, 115 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11886557&FileExtension=pdf&FileName=Summary%20FAA_Redacted-Rel.pdf - Photos (courtesy of FAA) (item 3, PDF, 7 pages, 2.6 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11886608&FileExtension=pdf&FileName=Photographs%20(FAA)-Rel.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.