# NTSB GAA16CA143: Bell 47, N568TB, Agua Dulce, CA, March 2, 2016 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Data collection · Final report - Date: March 2, 2016, 09:30 local (17:30 UTC) - Place: Agua Dulce, CA - Coordinates: 34.567501, -118.308334 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=34.5675&lon=-118.3083&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Defining event: [Enroute-cruise: Miscellaneous/other](https://openairdocs.org/ntsb-events/900) - Highest injury: Minor injuries - Injuries: 1 minor - Status: Completed, report April 5, 2016 - Report: Approved by Office Director - NTSB office: General Aviation Accidents - Parties: FAA Van Nuys FSDO - NTSB case key (mKey): 92800 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=GAA16CA143 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/92800/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=92800 - Page: https://openairdocs.org/ntsb/GAA16CA143 ## Probable cause The pilot's failure to set the appropriate collective friction prior to releasing the collective in flight, which resulted in decreased main rotor pitch, settling with power, and an impact with terrain. ## 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: [Bell 47G, 4 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md?model=1181002), [All aircraft, 9,308 cases](https://openairdocs.org/ntsb-findings/02063040/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: [Bell 47G, 2 cases](https://openairdocs.org/ntsb-findings/02063015/cases.md?model=1181002), [All aircraft, 1,397 cases](https://openairdocs.org/ntsb-findings/02063015/cases.md) - [Performance/control parameters: prop/rotor parameters](https://openairdocs.org/ntsb-findings/01062052): Aircraft › Aircraft oper/perf/capability · Not attained/maintained; cases with it: [Bell 47G, 1 case](https://openairdocs.org/ntsb-findings/01062052/cases.md?model=1181002), [All aircraft, 182 cases](https://openairdocs.org/ntsb-findings/01062052/cases.md) - [Performance/control parameters: powerplant parameters](https://openairdocs.org/ntsb-findings/01062050): Aircraft › Aircraft oper/perf/capability · Not attained/maintained; cases with it: [Bell 47G, 1 case](https://openairdocs.org/ntsb-findings/01062050/cases.md?model=1181002), [All aircraft, 81 cases](https://openairdocs.org/ntsb-findings/01062050/cases.md) - [Performance/control parameters: descent rate](https://openairdocs.org/ntsb-findings/01062037): Aircraft › Aircraft oper/perf/capability · Not attained/maintained; cases with it: [Bell 47G, 1 case](https://openairdocs.org/ntsb-findings/01062037/cases.md?model=1181002), [All aircraft, 242 cases](https://openairdocs.org/ntsb-findings/01062037/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Enroute-cruise: Miscellaneous/other](https://openairdocs.org/ntsb-events/900) (defining event); cases with it: [Bell 47G, 1 case](https://openairdocs.org/ntsb-events/900/sequence.md?model=1181002), [All aircraft, 1,557 cases](https://openairdocs.org/ntsb-events/900/sequence.md) - [Enroute-cruise: Attempted remediation/recovery](https://openairdocs.org/ntsb-events/060); cases with it: [Bell 47G, 1 case](https://openairdocs.org/ntsb-events/060/sequence.md?model=1181002), [All aircraft, 1,428 cases](https://openairdocs.org/ntsb-events/060/sequence.md) - [Enroute-cruise: Loss of control in flight](https://openairdocs.org/ntsb-events/240); cases with it: [Bell 47G, 2 cases](https://openairdocs.org/ntsb-events/240/sequence.md?model=1181002), [All aircraft, 5,010 cases](https://openairdocs.org/ntsb-events/240/sequence.md) - [Maneuvering-low-alt flying: Settling with power/vortex ring state](https://openairdocs.org/ntsb-events/244); cases with it: [Bell 47G, 1 case](https://openairdocs.org/ntsb-events/244/sequence.md?model=1181002), [All aircraft, 52 cases](https://openairdocs.org/ntsb-events/244/sequence.md) - [Maneuvering-low-alt flying: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Bell 47G, 2 cases](https://openairdocs.org/ntsb-events/470/sequence.md?model=1181002), [All aircraft, 10,154 cases](https://openairdocs.org/ntsb-events/470/sequence.md) - [Maneuvering-low-alt flying: Off-field or emergency landing](https://openairdocs.org/ntsb-events/440); cases with it: [Bell 47G, 3 cases](https://openairdocs.org/ntsb-events/440/sequence.md?model=1181002), [All aircraft, 3,368 cases](https://openairdocs.org/ntsb-events/440/sequence.md) ## Analysis The helicopter pilot reported that while flying about 300 feet above a ridge with an elevation of 4,900 feet at 10 miles per hour (8.68 knots), he could not hear very well in his headset and needed to adjust the volume. He reported that he removed his left hand from the collective and used it to hold the cyclic so he could use his right hand to adjust the volume on his headset. During this process, he reported that he forgot to increase the friction on the collective prior to removing his left hand. He further reported that the collective "dropped which decreased main rotor pitch causing the engine to overspeed." The pilot reported that the helicopter started to spin to the right; he grabbed the collective, reduced throttle, and then increased the collective pitch. He reported that the helicopter "experienced settling with power," and spun around 8 to 10 times. He further reported that the helicopter landed hard at the top of a ridge and rolled onto its right side. The helicopter sustained substantial damage to the fuselage, main rotor system, tailboom, and tail rotor system. The pilot verified that there were no preimpact mechanical failures or malfunctions with the airframe or engine that would have precluded normal operation. As a safety recommendation, the pilot stated he "should have increased the collective friction prior to removing his left hand from the collective stick." He also stated that "the problem was made worse because the helicopter was only 300 feet above ground level at 10 miles per hour [8.68 knots]." The Federal Aviation Administration (FAA) has published FAA-H-8083-21 Helicopter Flying Handbook (2012). This handbook discusses the function of the collective and states in part: "An adjustable friction control helps prevent inadvertent collective pitch movement." This handbook also discusses recovery from a settling with power condition and states in part: "When recovering from a settling with power condition, the pilot tends first to try to stop the descent by increasing collective pitch. However, this only results in increasing the stalled area of the rotor, thereby increasing the rate of descent. Since inboard portions of the blades are stalled, cyclic control may be limited. Recovery is accomplished by increasing airspeed, and/or partially lowering collective pitch. In many helicopters, lateral cyclic combined with lateral tail rotor thrust will produce the quickest exit from the hazard assuming that there are no barriers in that direction. In a fully developed vortex ring state, the only recovery may be to enter autorotation to break the vortex ring state." The pilot reported that he utilized a 4-point restraint system installed in the helicopter and sustained minor injuries. He also reported that "I credit the shoulder harness restraint with keeping my injuries from being far worse." ## Factual narrative The helicopter pilot reported that while flying about 300 feet above a ridge with an elevation of 4,900 feet at 10 miles per hour (8.68 knots), he could not hear very well in his headset and needed to adjust the volume. He reported that he removed his left hand from the collective and used it to hold the cyclic so he could use his right hand to adjust the volume on his headset. During this process, he reported that he forgot to increase the friction on the collective prior to removing his left hand. He further reported that the collective "dropped which decreased main rotor pitch causing the engine to overspeed." The pilot reported that the helicopter started to spin to the right; he grabbed the collective, reduced throttle, and then increased the collective pitch. He reported that the helicopter "experienced settling with power," and spun around 8 to 10 times. He further reported that the helicopter landed hard at the top of a ridge and rolled onto its right side. The helicopter sustained substantial damage to the fuselage, main rotor system, tailboom, and tail rotor system. The pilot verified that there were no preimpact mechanical failures or malfunctions with the airframe or engine that would have precluded normal operation. As a safety recommendation, the pilot stated he "should have increased the collective friction prior to removing his left hand from the collective stick." He also stated that "the problem was made worse because the helicopter was only 300 feet above ground level at 10 miles per hour [8.68 knots]." The Federal Aviation Administration (FAA) has published FAA-H-8083-21 Helicopter Flying Handbook (2012). This handbook discusses the function of the collective and states in part; An adjustable friction control helps prevent inadvertent collective pitch movement. This handbook also discusses recovery from a settling with power condition and states in part; When recovering from a settling with power condition, the pilot tends first to try to stop the descent by increasing collective pitch. However, this only results in increasing the stalled area of the rotor, thereby increasing the rate of descent. Since inboard portions of the blades are stalled, cyclic control may be limited. Recovery is accomplished by increasing airspeed, and/or partially lowering collective pitch. In many helicopters, lateral cyclic combined with lateral tail rotor thrust will produce the quickest exit from the hazard assuming that there are no barriers in that direction. In a fully developed vortex ring state, the only recovery may be to enter autorotation to break the vortex ring state. The pilot reported that he utilized a 4-point restraint system installed in the helicopter and sustained minor injuries. He also reported that "I credit the shoulder harness restraint with keeping my injuries from being far worse." ## Aircraft - Registration: [N568TB](https://openairdocs.org/aircraft/N568TB), registered now, S/N 85 (OpenAirDocs) - Reported make and model: BELL 47 (G2) - Registry model: [Bell 47G](https://openairdocs.org/model/bell-47g) (registry code 1181002) (OpenAirDocs) - Category: Helicopter - Serial number: 85 - Year built: 1948 - Airframe hours: 5818 - Engines: Lycoming VO435A1F 260 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Operator: Thomas J. White - Registered owner: Thomas J. White - Airworthiness certificate: Standard, Normal - Last inspection: November 21, 2015 - Departed: WJF, LANCASTER, CA - Destination: L70, AGUA DULCE, CA - Equipment: None ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 57; injuries: minor; private; airplane ratings: single-engine land; medical: class 3, with waivers/limitations; last flight review November 24, 2015; seat: left; restraint: 4-point; flight hours: 709 total, 137 in this make and model, 585 as pilot in command, 7 in the last 90 days, 1 in the last 30 days, 0.5 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 290° at 13 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 75 °F, dew point 18 °F - Altimeter: 30.10 inHg - Observed at: KWJF, 11 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 20160302006439A](https://openairdocs.org/incident/20160302006439A), Mar 2, 2016: Bell 47G, Agua Dulce, CA, Substantial damage. On March 2, 2016, at 0900 PDT, accident aircraft N568TB, departed w.j. fox field (wjf), lancaster, CA, heading for Agua Dulce airpark (L70), at approximately… ## Docket (3 files) The files NTSB released with the investigation on March 22, 2016, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=92800. 3.4 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 2.6 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40437933&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.PDF - Pilot's Statement (item 2, .PDF, 166 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40437934&FileExtension=.PDF&FileName=Pilot%27s%20Statement-Master.PDF - Accident Photographs (Courtesy of Pilot and Pilot's Friend) (item 3, .PDF, 6 photos, 702 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40437935&FileExtension=.PDF&FileName=Accident%20Photographs%20(Courtesy%20of%20Pilot%20and%20Pilot%27s%20Friend)-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.