# Tail rotor drive system - Type: NTSB finding section - Path: [Aircraft](https://openairdocs.org/ntsb-findings/01) › [Aircraft propeller/rotor](https://openairdocs.org/ntsb-findings/0104) › Tail rotor drive system - NTSB code: 010465 - Cases: 46 - In the probable cause: 41 - Fatal cases: 3 - All cases: https://openairdocs.org/ntsb-findings/010465/cases.md - Cases with it in the probable cause: https://openairdocs.org/ntsb-findings/010465/cases.md?cause=1 - Page: https://openairdocs.org/ntsb-findings/010465 ## Cases per year (in the probable cause / all) - 2008: 4 / 5 - 2009: 0 / 1 - 2011: 4 / 4 - 2012: 5 / 7 - 2013: 3 / 3 - 2014: 1 / 1 - 2015: 7 / 7 - 2016: 1 / 1 - 2017: 1 / 1 - 2018: 1 / 1 - 2019: 2 / 2 - 2020: 1 / 1 - 2021: 4 / 4 - 2022: 3 / 3 - 2024: 4 / 5 ## Findings - [Tail rotor drive shaft](https://openairdocs.org/ntsb-findings/01046510): 25 cases, 20 in the probable cause - [Tail rotor gearbox](https://openairdocs.org/ntsb-findings/01046520): 12 cases, 12 in the probable cause - [Tail rotor drive system, general](https://openairdocs.org/ntsb-findings/01046500): 10 cases, 10 in the probable cause ## Defining events in these cases - [Sys/Comp malf/fail (non-power)](https://openairdocs.org/ntsb-events/330): 15 cases - [Flight control sys malf/fail](https://openairdocs.org/ntsb-events/333): 12 cases - [Part(s) separation from AC](https://openairdocs.org/ntsb-events/338): 6 cases - [Loss of tail rotor effectiveness](https://openairdocs.org/ntsb-events/242): 3 cases - [Loss of control in flight](https://openairdocs.org/ntsb-events/240): 3 cases - [Miscellaneous/other](https://openairdocs.org/ntsb-events/900): 2 cases - [Aircraft structural failure](https://openairdocs.org/ntsb-events/337): 2 cases - [External load event (Rotorcraft)](https://openairdocs.org/ntsb-events/480): 1 cases - [Powerplant sys/comp malf/fail](https://openairdocs.org/ntsb-events/340): 1 cases - [Low altitude operation/event](https://openairdocs.org/ntsb-events/220): 1 cases ## Aircraft models (registry) - [Robinson Helicopter R44 II](https://openairdocs.org/model/robinson-helicopter-r44-ii): 3 cases - [Robinson Helicopter R44](https://openairdocs.org/model/robinson-helicopter-r44): 3 cases - [Robinson Helicopter R22 BETA](https://openairdocs.org/model/robinson-helicopter-r22-beta): 2 cases - [Hiller UH-12E](https://openairdocs.org/model/hiller-uh-12e): 2 cases - [Bell 206L-3](https://openairdocs.org/model/bell-206l-3): 2 cases - [Sikorsky S-76A](https://openairdocs.org/model/sikorsky-s-76a): 1 cases - [Sikorsky S-92A](https://openairdocs.org/model/sikorsky-s-92a): 1 cases - [Schweizer 269C](https://openairdocs.org/model/schweizer-269c): 1 cases - [Robinson Helicopter R22 MARINER](https://openairdocs.org/model/robinson-helicopter-r22-mariner): 1 cases - [Hughes Helicopters HUGHES 369D](https://openairdocs.org/model/hughes-helicopters-hughes-369d): 1 cases ## Other findings in the same cases - [Aircraft control](https://openairdocs.org/ntsb-findings/02063040) (Personnel issues): 4 cases - [Tail rotor blade](https://openairdocs.org/ntsb-findings/01046410) (Aircraft): 4 cases - [Not determined, general](https://openairdocs.org/ntsb-findings/05000000) (Not determined): 3 cases - [Scheduled/routine maintenance](https://openairdocs.org/ntsb-findings/02062010) (Personnel issues): 3 cases - [Yaw control](https://openairdocs.org/ntsb-findings/01062024) (Aircraft): 3 cases - [Directional control](https://openairdocs.org/ntsb-findings/01062020) (Aircraft): 3 cases - [Installation](https://openairdocs.org/ntsb-findings/02062035) (Personnel issues): 2 cases - [Modification/alteration](https://openairdocs.org/ntsb-findings/02062030) (Personnel issues): 2 cases - [Decision making/judgment](https://openairdocs.org/ntsb-findings/02041520) (Personnel issues): 2 cases - [Descent rate](https://openairdocs.org/ntsb-findings/01062037) (Aircraft): 2 cases ## Newest cases - [NTSB ERA25LA040](https://openairdocs.org/ntsb/ERA25LA040), Nov 5, 2024: Hughes 369D (N11AS), Waycross, GA, substantial damage. Probable cause: An encounter with a foreign object, which resulted in a loss of control and collision with terrain. - [NTSB ANC24LA077](https://openairdocs.org/ntsb/ANC24LA077), Aug 19, 2024: Robinson R44 (N740RH), Honolulu, HI, substantial damage. Probable cause: A failure of the flex plate yoke flange assembly due to incorrectly torqued bolts. Contributing was the maintenance personnel’s inadequate inspection of the tail rotor flex plate assembly. - [NTSB ERA24LA263](https://openairdocs.org/ntsb/ERA24LA263), Jun 14, 2024: Rotorway Exec (N99TE), Alva, FL, substantial damage. Probable cause: A loss of tail rotor control as a result of unsecured tail rotor drive belt tensioner bolts. - [NTSB ERA24LA205](https://openairdocs.org/ntsb/ERA24LA205), May 1, 2024: Airbus Helicopters AS350B3 (N413JM), Plant City, FL, substantial damage. Probable cause: The pilot’s inadequate yaw control of the helicopter while maneuvering at a low altitude and airspeed, which resulted in a hard landing. - [NTSB ANC24LA013](https://openairdocs.org/ntsb/ANC24LA013), Feb 11, 2024: Robinson Helicopter R44 II (N74868), Glacier View, AK, substantial damage. Probable cause: A sudden stoppage of the tail rotor for unknown reasons, which resulted in the tortional overload failure of the tail rotor driveshaft. - [NTSB WPR23LA004](https://openairdocs.org/ntsb/WPR23LA004), Oct 1, 2022: Bell 206B (N284CA), Fresno, CA, substantial damage. Probable cause: The disbond of a tail rotor drive shaft splined adapter, which resulted in a loss of tail rotor drive and a subsequent hard landing. - [NTSB WPR22LA340](https://openairdocs.org/ntsb/WPR22LA340), Sep 10, 2022: Bell Helicopter Textron 206L-1 (N242BH), Banning, CA, substantial damage. Probable cause: The improper attachment of the tail rotor drive shaft to the air conditioner drive pulley without a drive ring, which resulted in the failure of the hardware, a loss of tail rotor drive, and the loss… - [NTSB WPR22LA084](https://openairdocs.org/ntsb/WPR22LA084), Jan 23, 2022: Bell UH-1E (N333XL), Gustine, CA, substantial damage. Probable cause: Failure of the 90° gearbox due to the lack of lubricating oil, which resulted in a loss of rotational drive to the tail rotor and a subsequent loss of control of the helicopter. - [NTSB ERA21LA386](https://openairdocs.org/ntsb/ERA21LA386), Sep 29, 2021: Hiller UH-12E (N430NR), Millen, GA, substantial damage. Probable cause: The improper reassembly of the tail rotor gearbox following maintenance, which resulted in fatigue failure of the input pinion gear shaft, and the subsequent loss of tail rotor drive. - [NTSB CEN21LA389](https://openairdocs.org/ntsb/CEN21LA389), Aug 27, 2021: Robinson Helicopter R22 Beta (N827SH), Arnaudville, LA, substantial damage. Probable cause: The loss of tail rotor drive due to a fatigue failure of the tail rotor gearbox output shaft, which resulted in a loss of control during landing. 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.