# Main rotor system, general

- Type: NTSB finding subsection
- Path: [Aircraft](https://openairdocs.org/ntsb-findings/01) › [Aircraft propeller/rotor](https://openairdocs.org/ntsb-findings/0104) › [Main rotor system](https://openairdocs.org/ntsb-findings/010462) › Main rotor system, general
- NTSB code: 01046200
- Cases: 25
- In the probable cause: 23
- Fatal cases: 4
- All cases: https://openairdocs.org/ntsb-findings/01046200/cases.md
- Cases with it in the probable cause: https://openairdocs.org/ntsb-findings/01046200/cases.md?cause=1
- Page: https://openairdocs.org/ntsb-findings/01046200

## Cases per year (in the probable cause / all)

- 2008: 3 / 3
- 2009: 1 / 1
- 2010: 2 / 2
- 2011: 2 / 2
- 2012: 2 / 2
- 2013: 4 / 4
- 2014: 0 / 1
- 2015: 3 / 4
- 2016: 1 / 1
- 2017: 1 / 1
- 2021: 1 / 1
- 2022: 1 / 1
- 2023: 1 / 1
- 2024: 1 / 1

## Defining events in these cases

- [Loss of control in flight](https://openairdocs.org/ntsb-events/240): 5 cases
- [Sys/Comp malf/fail (non-power)](https://openairdocs.org/ntsb-events/330): 4 cases
- [Miscellaneous/other](https://openairdocs.org/ntsb-events/900): 3 cases
- [Flight control sys malf/fail](https://openairdocs.org/ntsb-events/333): 3 cases
- [Powerplant sys/comp malf/fail](https://openairdocs.org/ntsb-events/340): 2 cases
- [Part(s) separation from AC](https://openairdocs.org/ntsb-events/338): 2 cases
- [Inflight upset](https://openairdocs.org/ntsb-events/271): 2 cases
- [Unknown or undetermined](https://openairdocs.org/ntsb-events/000): 2 cases
- [Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342): 1 cases
- [Loss of engine power (total)](https://openairdocs.org/ntsb-events/341): 1 cases

## Aircraft models (registry)

- [Bell Helicopter Textron 206L-1](https://openairdocs.org/model/bell-helicopter-textron-206l-1): 2 cases
- [Williams Helicopter UH-1H](https://openairdocs.org/model/williams-helicopter-uh-1h): 1 cases
- [Eurocopter AS 350 B2 ECUREUIL](https://openairdocs.org/model/eurocopter-as-350-b2-ecureuil): 1 cases
- [Sikorsky CH-54B](https://openairdocs.org/model/sikorsky-ch-54b): 1 cases
- [Robinson Helicopter R44](https://openairdocs.org/model/robinson-helicopter-r44): 1 cases
- [Robinson Helicopter R22 BETA](https://openairdocs.org/model/robinson-helicopter-r22-beta): 1 cases
- [Hughes Helicopters HUGHES 369D](https://openairdocs.org/model/hughes-helicopters-hughes-369d): 1 cases
- [Hiller UH-12E](https://openairdocs.org/model/hiller-uh-12e): 1 cases
- [Garlick Helicopters UH-1H](https://openairdocs.org/model/garlick-helicopters-uh-1h): 1 cases
- [Enstrom 280FX](https://openairdocs.org/model/enstrom-280fx): 1 cases

## Other findings in the same cases

- [Aircraft control](https://openairdocs.org/ntsb-findings/02063040) (Personnel issues): 7 cases
- [Not determined, general](https://openairdocs.org/ntsb-findings/05000000) (Not determined): 3 cases
- [Use of equip/system](https://openairdocs.org/ntsb-findings/02063015) (Personnel issues): 2 cases
- [Incorrect action performance](https://openairdocs.org/ntsb-findings/02041015) (Personnel issues): 2 cases
- [Spatial disorientation](https://openairdocs.org/ntsb-findings/02022025) (Personnel issues): 2 cases
- [Task monitoring/vigilance](https://openairdocs.org/ntsb-findings/02021520) (Personnel issues): 2 cases
- [Prop/rotor parameters](https://openairdocs.org/ntsb-findings/01062052) (Aircraft): 2 cases
- [Directional control](https://openairdocs.org/ntsb-findings/01062020) (Aircraft): 2 cases
- [Rotorcraft flight control, general](https://openairdocs.org/ntsb-findings/01046700) (Aircraft): 2 cases
- [Tail rotor, general](https://openairdocs.org/ntsb-findings/01046400) (Aircraft): 2 cases

## Newest cases

- [NTSB WPR25LA010](https://openairdocs.org/ntsb/WPR25LA010), Oct 9, 2024: Enstrom Helicopter 280C (N646H), Vale, OR, substantial damage. Probable cause: The pilot’s failure to maintain engine and rotor rpm during takeoff, that resulted in a hard landing.
- [NTSB CEN24LA013](https://openairdocs.org/ntsb/CEN24LA013), Oct 16, 2023: Magni M24 (N90HM), Mount Sterling, IL, substantial damage. Probable cause: The pilot’s failure to maintain gyroplane control on the downwind leg, which resulted in impact with terrain. Contributing to the accident was the pilot’s distraction.
- [NTSB CEN22LA318](https://openairdocs.org/ntsb/CEN22LA318), Jul 6, 2022: Hiller UH12E (N64272), Becker, MN, substantial damage. Probable cause: The in-flight failure of the main rotor mast hub due to several undetected fatigue fractures.
- [NTSB ERA21LA126](https://openairdocs.org/ntsb/ERA21LA126), Feb 4, 2021: Bell 206 (N820H), Pahokee, FL, substantial damage. Probable cause: A loss of main rotor rpm for reasons that could not be determined, which resulted in an autorotation and a subsequent hard landing and rollover.
- [NTSB ERA17LA257](https://openairdocs.org/ntsb/ERA17LA257), Jul 24, 2017: Robinson Helicopter R44 (N828RD), Myrtle Beach, SC, substantial damage. Probable cause: A loss of available power to the main rotor due to a fractured exhaust pushrod and housing, which allowed engine oil to coat the V-belts. Contributing to the accident was the pilot's decision to…
- [NTSB WPR16LA069](https://openairdocs.org/ntsb/WPR16LA069), Feb 13, 2016: Bell 47G 3B 1 (N1181W), Carson City, NV, substantial damage. Probable cause: The pilot's failure to maintain sufficient main rotor rpm, which resulted in a loss of helicopter control and a dynamic rollover.
- [NTSB CEN16LA040](https://openairdocs.org/ntsb/CEN16LA040), Nov 14, 2015: Robinson Helicopter R22 Beta (N7058Z), Sugarland, TX, substantial damage. Probable cause: The overspeed of the main rotor system for reasons that could not be determined based on the available information.
- [NTSB GAA15LA191](https://openairdocs.org/ntsb/GAA15LA191), Jul 17, 2015: Celier Xenon RST (N402ED), Livingston, TX, substantial damage. Probable cause: The pilot’s loss of directional control after aborting the takeoff due to a grinding noise coming from the main rotor area, which resulted in a runway excursion.
- [NTSB WPR15LA178](https://openairdocs.org/ntsb/WPR15LA178), May 31, 2015: Garlick Helicopters UH 1H (N462CC), Cove, OR, substantial damage. Probable cause: The failure of the engine-to-transmission drive shaft coupling assembly due to a fatigue fracture of one of its attachment bolts, which resulted in a loss of power to the main rotor.
- [NTSB CEN15FA126](https://openairdocs.org/ntsb/CEN15FA126), Jan 26, 2015: Enstrom 280FX (N86235), Erie, CO, destroyed, 2 fatal. Probable cause: An in-flight failure of the helicopter's #2 main rotor spindle due to undetected fatigue cracking, which resulted in an in-flight breakup. Contributing to failure were the nonconforming thread root…

NTSB has coded findings and defining events since 2008; earlier cases used its older occurrence and cause codes and aren't counted.

Findings: https://openairdocs.org/ntsb-findings.md. Defining events: https://openairdocs.org/ntsb-events.md. Phases of flight: https://openairdocs.org/ntsb-phases.md. Every investigation, filtered by finding, event, phase, state, year or model: https://openairdocs.org/ntsb.md (for example ?state=MI&fatal=1).

NTSB's definitions: Accident and incident, 49 CFR 830.2 (https://www.ecfr.gov/current/title-49/subtitle-B/chapter-VIII/part-830/subpart-A/section-830.2), CICTT occurrence categories (PDF) (https://www.ntsb.gov/safety/data/Documents/datafiles/OccurrenceCategoryDefinitions.pdf), CICTT phases of flight (PDF) (https://www.ntsb.gov/safety/data/Documents/datafiles/PhaseofFlightDefinitions.pdf), and NTSB coding manual, before 2008 (PDF) (https://www.ntsb.gov/GILS/Documents/codman.pdf). NTSB publishes no definitions for its findings, only their names.

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