# NTSB investigations: Tail rotor gearbox

NTSB aviation accident and incident investigations since 1962: the probable cause, findings, aircraft, crew, weather and docket of each, linked to the FAA registry and the FAA’s own reports.

## Latest cases

- [NTSB WPR22LA084](https://openairdocs.org/ntsb/WPR22LA084.md): Bell UH-1E · Gustine, CA · Accident · No injuries · Class 3 · Limited · Final report · Jan 23, 2022 · N333XL · Substantial damage
  > 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.md): Hiller UH-12E · Millen, GA · Accident · Minor injuries · Class 3 · Limited · Final report · Sep 29, 2021 · N430NR · Substantial damage
  > 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 ERA20LA310](https://openairdocs.org/ntsb/ERA20LA310.md): Robinson R22 · Fort Myers, FL · Accident · No injuries · Class 3 · Limited · Final report · Sep 6, 2020 · N194HC · Substantial damage
  > Foreign object damage of the turning tailrotor by a soft-bodied object, which resulted in the sudden stoppage of the tailrotor and the catastrophic failure of the tailrotor assembly and its mount structure.
- [NTSB WPR17LA002](https://openairdocs.org/ntsb/WPR17LA002.md): Tamarack Helicopters UH-1H · Gila Bend, AZ · Accident · Minor injuries · Limited investigation · Final report · Oct 5, 2016 · N175SF · Substantial damage
  > The separation of the 90° tail rotor gearbox assembly as a result of fatigue to the tail rotor gearbox input quill assembly attachment studs due to the helicopter experiencing highly repetitive agricultural flight profiles for which it was not designed.
- [NTSB ANC15LA073](https://openairdocs.org/ntsb/ANC15LA073.md): Robinson Helicopter R44 · Fort Glenn, AK · Accident · No injuries · Limited investigation · Final report · Sep 19, 2015 · N7162R · Substantial damage
  > The separation of the tail rotor gearbox from the tailboom attachment point due to overstress loads imposed by a tail rotor blade imbalance as the result of impact with an undetermined object during low-level flight operations.
- [NTSB CEN15LA379](https://openairdocs.org/ntsb/CEN15LA379.md): Robinson Helicopter R44 II · Ketchum, OK · Accident · Minor injuries · Limited investigation · Final report · Aug 25, 2015 · N444KD · Substantial damage
  > The separation of the tail rotor gearbox from the tailboom aft bulkhead due to overstress loads imposed by a blade imbalance from an in-flight impact with an undetermined object.
- [NTSB ANC13TA076](https://openairdocs.org/ntsb/ANC13TA076.md): Bell UH-1B · Tok, AK · Accident · No injuries · Final report · Aug 8, 2013 · N70NW · Substantial damage
  > The failure of the tail rotor crosshead bearing, which resulted in a loss of tail rotor control.
- [NTSB CEN13FA192](https://openairdocs.org/ntsb/CEN13FA192.md): Sikorsky S-76A++ · Grand Lake, LA · Accident · 3 fatal · Field investigation · Final report · Mar 15, 2013 · N574EH · Destroyed
  > Fracture of the red tail rotor blade spar, which resulted in the separation and departure of the red tail rotor blade from the helicopter and subsequent compromised tail gearbox. The red tail rotor blade was not recovered, thus the cause of the initial…
- [NTSB WPR13FA006](https://openairdocs.org/ntsb/WPR13FA006.md): Garlick Helicopters UH-1H · Shady Cove, OR · Accident · Minor injuries · Field investigation · Final report · Oct 7, 2012 · N1577 · Substantial damage
  > The separation of the tail rotor gearbox and tail rotor assembly as a result of fatigue to the tail rotor gearbox input quill assembly attachment studs.
- [NTSB CEN12LA120](https://openairdocs.org/ntsb/CEN12LA120.md): Continental Copters 47G2 · Lohn, TX · Accident · Serious injuries · Limited investigation · Final report · Jan 1, 2012 · N9021R · Substantial damage
  > The improper installation of the tail rotor gearbox by maintenance personnel, which led to accelerated wear of the ring and pinion gears, resulting in the loss of tail rotor effectiveness and subsequent forced landing.
- [NTSB LAX08LA183](https://openairdocs.org/ntsb/LAX08LA183.md): Robinson R44 II · Topanga, CA · Accident · Minor injuries · Limited investigation · Final report · Jun 15, 2008 · N168AG · Substantial damage
  > The in-flight separation of the tail rotor gear box for an undetermined reason. Contributing to the accident was the hilly terrain, which was unsuitable for a forced landing.
- [NTSB DFW08LA100](https://openairdocs.org/ntsb/DFW08LA100.md): Hiller UH-12E · Quinton, OK · Accident · No injuries · Limited investigation · Final report · Apr 7, 2008 · N34SD · Substantial damage
  > An undetermined mechanical malfuction associated with the tail rotor drive system which led to a loss of control.

## The whole list in SQL

Runs in DuckDB 1.2 or later on the release's Parquet files over HTTPS:

```sql
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", '01046520'))
ORDER BY c."eventDate" DESC, c."ntsbNumber" DESC
```

This list as a web page: https://openairdocs.org/ntsb-findings/01046520/cases

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