# NTSB CEN13LA395: Bell 47G-3B-1, N7924S, Plover, WI, July 6, 2013 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Limited investigation · Final report - Date: July 6, 2013, 11:10 local (16:10 UTC) - Place: Plover, WI - Coordinates: 44.431945, -89.558891 - Nearby events: https://openairdocs.org/map.md?lat=44.4319&lon=-89.5589&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Defining event: [Maneuvering-low-alt flying: Low altitude operation/event](https://openairdocs.org/ntsb-events/220) - Highest injury: Minor injuries - Injuries: 1 minor - Status: Completed, report March 13, 2014 - Report: Approved by Office Director - NTSB office: Central Region - Parties: FAA Milwaukee FSDO - NTSB case key (mKey): 87400 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN13LA395 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/87400/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=87400 - Page: https://openairdocs.org/ntsb/CEN13LA395 ## Probable cause The pilot’s failure to maintain proper engine rpm, which resulted in a high rate of descent and ground impact. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Action: incorrect action performance](https://openairdocs.org/ntsb-findings/02041015): Personnel issues › Action/decision · Pilot (probable cause); cases with it: [Bell 47G-3B-1, 2 cases](https://openairdocs.org/ntsb-findings/02041015/cases.md?model=1181028), [All aircraft, 1,386 cases](https://openairdocs.org/ntsb-findings/02041015/cases.md) - [Performance/control parameters: prop/rotor parameters](https://openairdocs.org/ntsb-findings/01062052): Aircraft › Aircraft oper/perf/capability · Not attained/maintained (probable cause); cases with it: [Bell 47G-3B-1, 2 cases](https://openairdocs.org/ntsb-findings/01062052/cases.md?model=1181028), [All aircraft, 182 cases](https://openairdocs.org/ntsb-findings/01062052/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: [Bell 47G-3B-1, 1 case](https://openairdocs.org/ntsb-findings/01062037/cases.md?model=1181028), [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. - [Maneuvering-low-alt flying: Low altitude operation/event](https://openairdocs.org/ntsb-events/220) (defining event); cases with it: [Bell 47G-3B-1, 2 cases](https://openairdocs.org/ntsb-events/220/sequence.md?model=1181028), [All aircraft, 780 cases](https://openairdocs.org/ntsb-events/220/sequence.md) - [Maneuvering-low-alt flying: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Bell 47G-3B-1, 10 cases](https://openairdocs.org/ntsb-events/470/sequence.md?model=1181028), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) ## Analysis The pilot reported that the engine was at 3,200 rpm (full power) during takeoff. He completed the last aerial application pass, initiated a climb, and made a 180-degree turn. During the course reversal, the engine power was about 2,000 rpm. He was increasing the power during the rollout when the helicopter descended rapidly and impacted the field. A postaccident examination of the airframe and engine revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation. ## Factual narrative On July 6, 2013, about 1110 central daylight time, a Bell 47G-3B-1 helicopter, N7924S, sustained substantial during an agricultural aerial application flight near Plover, Wisconsin. The pilot was performing a 180-degree course reversal when the helicopter impacted the terrain. The pilot, the sole occupant, received minor injuries. The helicopter was registered to 102 Leasing LLC and operated by Reabe Spraying Service under the provisions of the 14 Code of Federal Regulations Part 137 as an aerial application flight. Visual meteorological conditions prevailed at the time of the accident, and no flight plan was filed. The flight originated from a private airstrip near Plover, Wisconsin, about 1105. The pilot reported that he was finishing the field after having flown about 5 hours of aerial application flights for the day. On the accident flight, the helicopter was fueled with about 1/2 tank of fuel and about 4 gallons of pesticide. He completed the last pass along the west side of the field traveling to the north. He turned to the southeast and completed spraying a short segment of the field. He pulled up and did a 180-degree turn to the right. During the turn, the engine and rotor rpm were about 2,000 rpm when he started to reapply power. He rolled out of the turn and the helicopter impacted the field. During an interview with a Federal Aviation Administration (FAA) inspector, the pilot reported that the engine was at 3,200 rpm (full power) during takeoff. During the course reversal turn, the engine was about 2,000 rpm, and he was reapplying power back to 3,200 rpm during the rollout when the helicopter impacted the field. FAA inspectors examined the helicopter and determined that the collective, cyclic, and anti-torque pedals exhibited flight control continuity. The examination of the engine's fuel system and ignition system revealed no anomalies. The compression test revealed that all six cylinders had normal compression readings. The main rotor tachometer and engine tachometer were checked and were found operational. A teardown of the engine was conducted and no anomalies were noted which would have prevented normal operation. ## Aircraft - Registration: [N7924S](https://openairdocs.org/deregistered/N7924S-2019-02-25), registration cancelled 2019-02-25, S/N 6595, built 1966 (OpenAirDocs) - Reported make and model: BELL 47G-3B-1 - Registry model: [Bell 47G-3B-1](https://openairdocs.org/model/bell-47g-3b-1) (registry code 1181028) (OpenAirDocs) - Registry engine: [Lycoming TVO-435-GIA](https://openairdocs.org/engine/lycoming-tvo-435-gia) (registry code 41526, turbo-prop) (OpenAirDocs) - Category: Helicopter - Serial number: 6595 - Engines: LYCOMING TV0-435 A1F 260 horsepower reciprocating - Damage: Substantial damage - Flight: Aerial application, Part 137 - Operator: Reabe Spraying Service - Registered owner: 102 Leasing LLC - Airworthiness certificate: Special, Restricted (Special) - Departed: Plover, WI - Destination: Plover, WI ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 68; injuries: minor; commercial; airplane ratings: single-engine land, multi-engine land; instrument ratings: helicopter; medical: class 2, with waivers/limitations; last flight review June 30, 2012; seat: right; flight hours: 30,000 total, 1,500 in this make and model ## Weather - Conditions: Visual (VMC), Day - Wind: 190° at 8 knots - Visibility: 10 statute miles - Temperature: 81 °F, dew point 63 °F - Altimeter: 30.01 inHg - Observed at: STE, 12 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 20130706011269A](https://openairdocs.org/incident/20130706011269A), Jul 6, 2013: Bell 47G-3B-1, Plover, WI, Substantial damage. On 7/6/13 at approximately 1110 central time (1610Z) N7924S, a Bell 47 helicopter piloted by [privacy data omitted] was involved in an accident 3 miles sw of… ## Other investigations on N7924S (2) 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 CHI76FEV02](https://openairdocs.org/ntsb/CHI76FEV02), Jul 11, 1975: Bell 47G (N7924S), Forsyth, IL, substantial damage - [NTSB MKC70I0081](https://openairdocs.org/ntsb/MKC70I0081), Aug 2, 1969: Bell 47G3B1 (N7924S), Hill City, SD, incident, minor damage ## Docket (6 files) The files NTSB released with the investigation on December 4, 2013, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=87400. 9.1 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 3.8 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40401764&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - Field Diagram (item 2, .PDF, 254 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40401765&FileExtension=.PDF&FileName=Field%20Diagram-Redacted.PDF - FAA Record of Conversation (item 3, .PDF, 26 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40401895&FileExtension=.PDF&FileName=FAA%20Record%20of%20Conversation-Master.PDF - Engine Inspection Notes (item 4, .PDF, 711 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40401766&FileExtension=.PDF&FileName=Engine%20Inspection%20Notes-Master.PDF - Photo 1. View of the wreckage in the field. (item 5, .PDF, 2.0 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40401812&FileExtension=.PDF&FileName=Photo%201.%20View%20of%20the%20wreckage%20in%20the%20field.-Master.PDF - Photo 2. View of the wreckage in the field. (item 6, .PDF, 2.3 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40401813&FileExtension=.PDF&FileName=Photo%202.%20View%20of%20the%20wreckage%20in%20the%20field.%20-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.