# NTSB investigations: Franklin 6V4 series: Airframe/component/system failure/malfunction

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 LAX06LA030](https://openairdocs.org/ntsb/LAX06LA030.md): Bell 47D1 · Rancho Murieta, CA · Accident · Serious injuries · Limited investigation · Final report · Nov 10, 2005 · N16356 · Substantial damage
  > a separation of the tail rotor assembly due to the reverse bending fatigue fracture of a tail rotor pitch change link bolt, resulting in a loss of control of the helicopter, and a hard landing during the uncontrolled descent.
- [NTSB ATL01LA108](https://openairdocs.org/ntsb/ATL01LA108.md): Bell 47G · Berry, AL · Accident · No injuries · Limited investigation · Final report · Sep 7, 2001 · N6327D · Substantial damage
  > The failure of the main rotor system stabilizer damper control horn assembly, resulting in an uncontrolled descent and subsequent collision with a tree and terrain.
- [NTSB MIA00LA111](https://openairdocs.org/ntsb/MIA00LA111.md): Hiller UH-12B · Sanford, FL · Accident · Minor injuries · Limited investigation · Final report · Mar 17, 2000 · N5304V · Substantial damage
  > The pilot's improper collective and cyclic control usage during an emergency descent, following the onset of a 1 to 1 vibration for undetermined reasons, resulting in the helicopter landing hard and rolling over.
- [NTSB CHI99LA012](https://openairdocs.org/ntsb/CHI99LA012.md): Hiller UH-12C · Clinton, IA · Accident · No injuries · Limited investigation · Final report · Oct 24, 1998 · N9739C · Substantial damage
  > the failure of the 90 degree gearbox for reasons undetermined. Factors were the failure of the gearbox, and it not being possible for the pilot to maintain control of the aircraft.
- [NTSB MIA98LA254](https://openairdocs.org/ntsb/MIA98LA254.md): Bell 47-D1 · Oxford, MS · Accident · Minor injuries · Limited investigation · Final report · Sep 29, 1998 · N755E · Substantial damage
  > The pilot's failure to maintain directional control due to vibration from the main rotor blade for undetermined reasons. A related finding was the improper repair of a crack in the laminant of the blue main rotor blade by other maintenance personnel.
- [NTSB FTW98LA144](https://openairdocs.org/ntsb/FTW98LA144.md): Bell 47D1 · Jeanerette, LA · Accident · Minor injuries · Limited investigation · Final report · Mar 11, 1998 · N13012 · Substantial damage
  > The in-flight disconnect of the rotating scissors due to the separation of its hinge bolt.
- [NTSB MIA94FA125](https://openairdocs.org/ntsb/MIA94FA125.md): Bell 47D1 · Marathon, FL · Accident · 2 fatal · Field investigation · Final report · Apr 22, 1994 · N9660 · Destroyed
  > Separation of the tail rotor gearbox and tail rotor blades for an undetermined reason. Factors related to the accident were: failure of maintenance personnel to follow the proper maintenance procedure after a previous tail rotor strike, and failure to conduct…
- [NTSB ATL92LA017](https://openairdocs.org/ntsb/ATL92LA017.md): Bell 47D-1 · Rome, GA · Accident · No injuries · Limited investigation · Final report · Oct 28, 1991 · N925V · Substantial damage
  > The failure of a tail rotor blade for undetermined reasons.
- [NTSB ATL89DLT03](https://openairdocs.org/ntsb/ATL89DLT03.md): Bell 47 · Shelbyville, TN · Accident · No injuries · Final report · May 12, 1989 · N908B · Substantial damage
  > Failure in the rotor drive system for unknown reasons. Contributing to the accident was the pilot's inability to perform an autorotation.
- [NTSB LAX82FA341](https://openairdocs.org/ntsb/LAX82FA341.md): Bell 47G-2 · San Diego, CA · Accident · Minor injuries · Field investigation · Final report · Sep 11, 1982 · N4242A · Destroyed
  > The plt was in the local pattern practicing maneuvers. After completing a quick stop maneuver & hovering, another takeoff was initiated. The plt stated that it seemed to take an unusual amount of forward cyclic to initiate forward flt. During the final…
- [NTSB NYC82DA087](https://openairdocs.org/ntsb/NYC82DA087.md): Hiller UH-12A · New Paltz, NY · Accident · No injuries · Final report · May 2, 1982 · N116S · Substantial damage
  > While cruising at 400 ft AGL, the pilot noticed a decay in the main rotor RPM; however, the engine RPM was reported to have remained constant. The pilot suspected a mechanical failure and elected to make a precautionary landing in an apple orchard. During the…

## 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 x.case_mkey FROM 'https://openairdocs.org/data/latest/ntsb_aircrafts.parquet' x WHERE x.engine_model_code IN ('27033')
    AND EXISTS (SELECT 1 FROM 'https://openairdocs.org/data/latest/ntsb_occurrences.parquet' o WHERE o.case_mkey = x.case_mkey AND o.aircrafts_position = x.position AND o."occurrenceNumber" = 1 AND o."occurrenceCode" = 130))
ORDER BY c."eventDate" DESC, c."ntsbNumber" DESC
```

This list as a web page: https://openairdocs.org/ntsb?engine=27033&occurrence=130

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