# Main rotor system - Type: NTSB finding section - Path: [Aircraft](https://openairdocs.org/ntsb-findings/01) › [Aircraft propeller/rotor](https://openairdocs.org/ntsb-findings/0104) › Main rotor system - NTSB code: 010462 - Cases: 104 - In the probable cause: 92 - Fatal cases: 32 - All cases: https://openairdocs.org/ntsb-findings/010462/cases.md - Cases with it in the probable cause: https://openairdocs.org/ntsb-findings/010462/cases.md?cause=1 - Page: https://openairdocs.org/ntsb-findings/010462 ## Cases per year (in the probable cause / all) - 2008: 7 / 9 - 2009: 5 / 6 - 2010: 8 / 8 - 2011: 8 / 9 - 2012: 7 / 8 - 2013: 8 / 8 - 2014: 3 / 5 - 2015: 7 / 9 - 2016: 8 / 8 - 2017: 4 / 4 - 2018: 2 / 2 - 2019: 3 / 3 - 2020: 4 / 4 - 2021: 4 / 4 - 2022: 3 / 4 - 2023: 6 / 6 - 2024: 4 / 4 - 2025: 1 / 3 ## Findings - [Main rotor blade system](https://openairdocs.org/ntsb-findings/01046210): 60 cases, 51 in the probable cause - [Main rotor system, general](https://openairdocs.org/ntsb-findings/01046200): 25 cases, 23 in the probable cause - [Main rotor mast/swashplate](https://openairdocs.org/ntsb-findings/01046230): 13 cases, 12 in the probable cause - [Main rotor head system](https://openairdocs.org/ntsb-findings/01046220): 10 cases, 10 in the probable cause - [Main rotor indicating system](https://openairdocs.org/ntsb-findings/01046240): 1 cases, 1 in the probable cause ## Defining events in these cases - [Sys/Comp malf/fail (non-power)](https://openairdocs.org/ntsb-events/330): 14 cases - [Loss of control in flight](https://openairdocs.org/ntsb-events/240): 13 cases - [Part(s) separation from AC](https://openairdocs.org/ntsb-events/338): 11 cases - [Miscellaneous/other](https://openairdocs.org/ntsb-events/900): 8 cases - [Flight control sys malf/fail](https://openairdocs.org/ntsb-events/333): 7 cases - [Hard landing](https://openairdocs.org/ntsb-events/092): 6 cases - [Mast bumping](https://openairdocs.org/ntsb-events/245): 5 cases - [Unknown or undetermined](https://openairdocs.org/ntsb-events/000): 5 cases - [Inflight upset](https://openairdocs.org/ntsb-events/271): 4 cases - [Abrupt maneuver](https://openairdocs.org/ntsb-events/270): 4 cases ## Aircraft models (registry) - [Hughes Helicopters HUGHES 369D](https://openairdocs.org/model/hughes-helicopters-hughes-369d): 8 cases - [Robinson Helicopter R22 BETA](https://openairdocs.org/model/robinson-helicopter-r22-beta): 7 cases - [Robinson Helicopter R44 II](https://openairdocs.org/model/robinson-helicopter-r44-ii): 5 cases - [Robinson Helicopter R44](https://openairdocs.org/model/robinson-helicopter-r44): 5 cases - [Robinson Helicopter R66](https://openairdocs.org/model/robinson-helicopter-r66): 3 cases - [Bell Helicopter Textron 206L-1](https://openairdocs.org/model/bell-helicopter-textron-206l-1): 3 cases - [Eurocopter AS 350 B2](https://openairdocs.org/model/eurocopter-as-350-b2): 2 cases - [Hiller UH-12E](https://openairdocs.org/model/hiller-uh-12e): 2 cases - [Enstrom F-28C](https://openairdocs.org/model/enstrom-f-28c): 2 cases - [Bell Helicopter Textron Canada 429](https://openairdocs.org/model/bell-helicopter-textron-canada-429): 2 cases ## Other findings in the same cases - [Aircraft control](https://openairdocs.org/ntsb-findings/02063040) (Personnel issues): 25 cases - [Not determined, general](https://openairdocs.org/ntsb-findings/05000000) (Not determined): 10 cases - [Incorrect action performance](https://openairdocs.org/ntsb-findings/02041015) (Personnel issues): 10 cases - [Use of equip/system](https://openairdocs.org/ntsb-findings/02063015) (Personnel issues): 9 cases - [Prop/rotor parameters](https://openairdocs.org/ntsb-findings/01062052) (Aircraft): 8 cases - [Performance/control parameters, general](https://openairdocs.org/ntsb-findings/01062000) (Aircraft): 5 cases - [Scheduled/routine inspection](https://openairdocs.org/ntsb-findings/02061520) (Personnel issues): 4 cases - [Incorrect action selection](https://openairdocs.org/ntsb-findings/02041010) (Personnel issues): 4 cases - [Task monitoring/vigilance](https://openairdocs.org/ntsb-findings/02021520) (Personnel issues): 4 cases - [Use of policy/procedure](https://openairdocs.org/ntsb-findings/02063032) (Personnel issues): 3 cases ## Newest cases - [NTSB CEN26LA081](https://openairdocs.org/ntsb/CEN26LA081), Dec 23, 2025: Ela ELA10 (N396S), Morris, IL, substantial damage. Probable cause: The pilot’s failure obtain the proper rotor rpm before applying power for the takeoff roll which resulted in a loss of control. - [NTSB WPR25LA203](https://openairdocs.org/ntsb/WPR25LA203), Jul 6, 2025: Robinson Helicopter R44 (N715SG), Park City, UT, substantial damage. Probable cause: The pilot’s failure to maintain rotor rpm during an approach to landing in a mountainous area, which resulted in a collision with terrain. - [NTSB WPR25LA093](https://openairdocs.org/ntsb/WPR25LA093), Feb 13, 2025: Airbus Helicopters EC 130 T2 (N3WL), Moab, UT, substantial damage. Probable cause: The inflight collision with debris during takeoff. - [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 WPR24LA319](https://openairdocs.org/ntsb/WPR24LA319), Sep 26, 2024: Bell 206L (N9984K), Fern Prairie, WA, substantial damage. Probable cause: An aeroelastic interaction between the helicopter’s main rotor blades and nodal beam system, which resulted in oscillations that exceeded the design limits of the tailboom. Contributing to the… - [NTSB CEN24LA358](https://openairdocs.org/ntsb/CEN24LA358), Sep 11, 2024: Hughes 369 (N8969F), Canton, MI, substantial damage. Probable cause: Fatigue cracking of the main rotor blade that occurred at an undetermined time. - [NTSB ANC24FA063](https://openairdocs.org/ntsb/ANC24FA063), Jul 11, 2024: Robinson Helicopter R44 (N144KW), Kekaha, HI, substantial damage, 3 fatal. Probable cause: An encounter with turbulence due to downdraft winds that resulted in mast bumping and an in-flight breakup. - [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 WPR23LA313](https://openairdocs.org/ntsb/WPR23LA313), Aug 9, 2023: Bell OH-58A (N861CC), Guernsey, CA, substantial damage. Probable cause: The pilot’s overpitching of the main rotor blades while maneuvering at low altitude in a high-temperature environment at high gross weight, which resulted in a reduction of engine and rotor speed,… - [NTSB ERA23LA326](https://openairdocs.org/ntsb/ERA23LA326), Aug 5, 2023: Hughes 369 (N353AH), Elberon, VA, substantial damage. Probable cause: The pilot’s failure to maintain clearance from a power line structure arm, which resulted in main rotor blade contact. 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. --- 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.