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Main rotor drive, general

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NTSB finding · Aircraft › Aircraft propeller/rotor › Main rotor drive

All 15 cases13 in the probable cause
Cases
15
In the probable cause
13 (87%)
Fatal cases
2
NTSB code
01046300

NTSB has coded findings and defining events since 2008. Earlier cases used its older occurrence and cause codes, so they aren’t counted here.

When and where

In green, cases where NTSB made it part of the probable cause; in gray, a factor or other finding. Findings are coded with the final report, often a year or more after the event, so the latest years are incomplete.

Cases per year

2008In the probable causeFactor only2026

Where

Open the map
Query with SQL
duckdb -csv -c "SELECT year(c.\"eventDate\") AS year, count(DISTINCT f.case_mkey) AS cases,
    count(DISTINCT f.case_mkey) FILTER (WHERE f.\"inProbableCause\") AS in_probable_cause
  FROM 'https://openairdocs.org/data/latest/ntsb_findings.parquet' f JOIN 'https://openairdocs.org/data/latest/ntsb_case_detail.parquet' c ON c.\"mKey\" = f.case_mkey
  WHERE starts_with(f.\"findingCode\", '01046300') AND c.\"eventDate\" >= DATE '2000-01-01'
  GROUP BY 1
  ORDER BY 1"

Prints the counts as CSV. It reads the release’s Parquet files over HTTPS, so there’s nothing to download first. Install DuckDB to run it.

In the same cases

Defining events
Aircraft models

Aircraft matched to the registry by N-number and date.

Other findings
Query with SQL
duckdb -csv -c "WITH matched AS (SELECT DISTINCT case_mkey, aircrafts_position FROM 'https://openairdocs.org/data/latest/ntsb_findings.parquet' WHERE starts_with(\"findingCode\", '01046300'))
  SELECT * FROM (
  SELECT 'Defining event' AS kind, e.\"tier2Number\" AS code, max(e.\"eventTier2Name\") AS name, count(DISTINCT f.case_mkey) AS cases
  FROM matched f JOIN 'https://openairdocs.org/data/latest/ntsb_events.parquet' e ON e.case_mkey = f.case_mkey AND e.aircrafts_position = f.aircrafts_position AND e.\"isDefiningEvent\"
  WHERE e.\"tier2Number\" <> ''
  GROUP BY ALL
  UNION ALL
  SELECT 'Aircraft model', a.aircraft_model_code, any_value(concat_ws(' ', m.manufacturer, m.model)), count(DISTINCT f.case_mkey)
  FROM matched f JOIN 'https://openairdocs.org/data/latest/ntsb_aircrafts.parquet' a ON a.case_mkey = f.case_mkey AND a.position = f.aircrafts_position
  LEFT JOIN 'https://openairdocs.org/data/latest/faa_aircraft_model.parquet' m ON m.code = a.aircraft_model_code
  WHERE a.aircraft_model_code IS NOT NULL
  GROUP BY ALL
  UNION ALL
  SELECT 'Other finding', left(g.\"findingCode\", 8), max(g.\"tier4Name\"), count(DISTINCT g.case_mkey)
  FROM 'https://openairdocs.org/data/latest/ntsb_findings.parquet' g
  WHERE g.case_mkey IN (SELECT case_mkey FROM matched) AND NOT starts_with(g.\"findingCode\", '01046300') AND g.\"findingCode\" GLOB '[0-9][0-9]*'
  GROUP BY ALL
  )
  QUALIFY row_number() OVER (PARTITION BY kind ORDER BY cases DESC) <= 10
  ORDER BY kind, cases DESC"

Prints the counts as CSV. It reads the release’s Parquet files over HTTPS, so there’s nothing to download first. Install DuckDB to run it.

Newest cases · 15

NTSB WPR24LA067Accident · No injuriesClass 3 · LimitedFinal reportBell 206B · El Centro, CAAn in-flight failure of the engine-to-transmission driveshaft due to a fatigue fracture of the forward-most flex plate in the forward KAflex coupling that resulted from a loose bolt attachment between the flex plate and the forward driveshaft coupling.…Dec 24, 2023 · N111PM · Substantial damageNTSB WPR21LA320Accident · Serious injuriesClass 3 · LimitedFinal reportRobinson Helicopter R22 Beta · West Jordan, UTThe pilot receiving instruction’s improper application of forward cyclic in a low rotor rpm condition and the instructor’s delayed remediation, which resulted in an impact with terrain.Aug 14, 2021 · N226WM · Substantial damageNTSB CEN20LA330Accident · Serious injuriesClass 3 · LimitedFinal reportRobinson R44 · Logan, IAThe failure of the lower actuator bearing support brackets, which resulted in the misalignment of the clutch actuator, a loss of belt tension on the main rotor drive system, and a subsequent forced landing.Aug 8, 2020 · N89LA · Substantial damageNTSB CEN17LA365Accident · No injuriesLimited investigationFinal reportGaddis Michael Exec 162 F · Plymouth, INA failure of the drive belt for reasons that could not be determined based on the available information.Sep 16, 2017 · N123XZ · Substantial damageNTSB CEN16LA096Accident · 1 fatalLimited investigationFinal reportRaymond Z Brown Condor · Centralia, ILThe failure of the prerotator belt, which impeded the engine's timing belt and resulted in a loss of engine power at low altitude.Feb 1, 2016 · N41852 · Substantial damageNTSB CEN14LA307Accident · No injuriesLimited investigationFinal reportRotorway Exec 162F · Mt. Comfort, INThe pilot’s installation of an unauthorized main rotor belt and his subsequent failure to properly inspect the belt, which resulted in inadequate belt tension, the belt’s failure, and the subsequent loss of engine power.Jun 21, 2014 · N6828D · Substantial damageNTSB WPR12FA191Accident · Serious injuriesField investigationFinal reportHughes 269C · Phoenix, AZA loss of tail rotor drive due to a fatigue failure of the main transmission pinion, which resulted in a loss of directional control during cruise flight.May 2, 2012 · N380TL · Substantial damageNTSB CEN11LA305Accident · Minor injuriesLimited investigationFinal reportD & D Rotorway Exec · Massillon, OHThe excessive wear on the secondary shaft, from the inner bearing race, which resulted in the transmission clutch disengagement and a loss of power to the rotor system.Apr 23, 2011 · N614S · Substantial damageNTSB ERA11LA216Accident · No injuriesLimited investigationFinal reportHiller UH-12E · Culpeper, VAMechanical failure of the transmission for reasons that could not be determined because the transmission could not be torn down.Mar 25, 2011 · N4033P · Substantial damageNTSB ERA10LA361Accident · No injuriesLimited investigationFinal reportRobinson Helicopter R22 Beta · West Melbourne, FLSeparation of the main rotor drive belts due to maintenance personnel’s failure to adequately inspect the upper drive sheave prior to installing the belts.Jul 15, 2010 · N74603 · Substantial damage
See all 15 cases
Query with SQL
duckdb -csv -c "SELECT c.\"ntsbNumber\", c.\"eventDate\", c.\"eventType\", c.\"eventCity\", c.\"eventStateOrRegion\", a.n_number, a.\"aircraftMake\", a.\"aircraftModel\", c.\"highestInjuryLevel\", c.\"totalFatal\", c.\"completionStatus\", c.report_url
  FROM 'https://openairdocs.org/data/latest/ntsb_case_detail.parquet' c LEFT JOIN 'https://openairdocs.org/data/latest/ntsb_aircrafts.parquet' a ON a.case_mkey = c.\"mKey\" AND a.position = 1
  WHERE c.\"mKey\" IN (SELECT f.case_mkey FROM 'https://openairdocs.org/data/latest/ntsb_findings.parquet' f WHERE starts_with(f.\"findingCode\", '01046300'))
  ORDER BY c.\"eventDate\" DESC, c.\"ntsbNumber\" DESC"

Prints the whole list as CSV. It reads the release’s Parquet files over HTTPS, so there’s nothing to download first. Install DuckDB to run it.