# NTSB investigations: Lycoming VO-435 series, 1991

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 FTW92LA044](https://openairdocs.org/ntsb/FTW92LA044.md): Hiller-Osborn UH-12D · Rio Medina, TX · Accident · No injuries · Limited investigation · Final report · Dec 2, 1991 · N67065 · Substantial damage
  > The pilot's improper flare during touchdown.
- [NTSB MIA92WA037](https://openairdocs.org/ntsb/MIA92WA037.md): Bell-Transworld 47G2 · David, Panama · Accident · No injuries · Foreign investigation · Nov 25, 1991 · N64589 · Substantial damage
- [NTSB FTW91LA166](https://openairdocs.org/ntsb/FTW91LA166.md): Bell 47G-5A · Pearsall, TX · Accident · Minor injuries · Limited investigation · Final report · Sep 26, 1991 · N59424 · Destroyed
  > The pilot's failure to maintain adequate visual lookout for obstacles during operations from a remote site.
- [NTSB CHI91FA294](https://openairdocs.org/ntsb/CHI91FA294.md): Bell-K Copter 47D1 · Laurie, MO · Accident · 3 fatal · Field investigation · Final report · Sep 15, 1991 · N7768 · Destroyed
  > Poor judgement of the pilot, due to impairment from consumption of alcoholic beverage before flight, his intentional buzzing, and his inadequate visual lookout (failure to see-and-avoid power lines).
- [NTSB MIA91LA215](https://openairdocs.org/ntsb/MIA91LA215.md): Bell 47G2A · Immokalee, FL · Accident · No injuries · Limited investigation · Final report · Sep 7, 1991 · N7573 · Substantial damage
  > The improper use of the flight controls by the pilot in command, which resulted in a collision with the ground and a nose over.
- [NTSB LAX91LA369](https://openairdocs.org/ntsb/LAX91LA369.md): Hiller UH12D · Sparks, NV · Accident · No injuries · Limited investigation · Final report · Aug 25, 1991 · N100HH · Substantial damage
  > The encounter with rough, unsuitable terrain during a precautionary landing. Contributing to the accident was the pilot's decision to make an autorotation after encountering an airframe vibration.
- [NTSB CHI91LA245](https://openairdocs.org/ntsb/CHI91LA245.md): Hiller 1345 · Michigan City, IN · Accident · Serious injuries · Limited investigation · Final report · Aug 3, 1991 · N57972 · Substantial damage
  > Fuel exhaustion due the pilot's delay in refueling. Factors related to the accident were pressure induced by others (passenger), and the absence of suitable terrain.
- [NTSB FTW91LA125](https://openairdocs.org/ntsb/FTW91LA125.md): Bell 47G-2 · Slidell, LA · Accident · No injuries · Limited investigation · Final report · Jul 22, 1991 · N312SH · Substantial damage
  > The pilot performing a touchdown autorotation to unsuitable terrain. Factors were the soft terrain and the inadequate supervision by the FAA inspector.
- [NTSB CHI91LA205](https://openairdocs.org/ntsb/CHI91LA205.md): Hiller UH-12D · Savoy, IL · Accident · No injuries · Limited investigation · Final report · Jul 2, 1991 · N94515 · Substantial damage
  > The pilot's failure to maintain tail rotor clearance from the ground. A related factor is the pilot's lack of total experience in helicopters.
- [NTSB FTW91LA091](https://openairdocs.org/ntsb/FTW91LA091.md): Bell 47D-1 · Peach Orchard, AR · Accident · No injuries · Limited investigation · Final report · Jun 5, 1991 · N8117 · Substantial damage
  > The pilot's failure to maintain adequate main rotor RPM resulting in deteriorated helicopter performance. A factor was the tailwind condition.
- [NTSB SEA91LA077](https://openairdocs.org/ntsb/SEA91LA077.md): Bell BH-47G2A · Waitsburg, WA · Accident · No injuries · Limited investigation · Final report · Mar 31, 1991 · N38926 · Substantial damage
  > The improper installation of the main rotor mast nut and lock washer by maintenance personnel which resulted in the separation of the main rotor system.
- [NTSB MIA91TL#03](https://openairdocs.org/ntsb/MIA91TL%2303.md): Bell 47-G5A · Titusville, FL · Accident · No injuries · Class 3 · Final report · Mar 27, 1991 · N7925J · Substantial damage
- [NTSB LAX91LA128](https://openairdocs.org/ntsb/LAX91LA128.md): Bell 47G-5A · Farmington, CA · Accident · No injuries · Limited investigation · Final report · Mar 10, 1991 · N59403 · Substantial damage
  > The contamination of the engine induction air filter. Soft terrain during the touchdown was a factor in the accident.

## 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 year(c."eventDate") = 1991
  AND c."mKey" IN (SELECT x.case_mkey FROM 'https://openairdocs.org/data/latest/ntsb_aircrafts.parquet' x WHERE x.engine_model_code IN ('41525'))
ORDER BY c."eventDate" DESC, c."ntsbNumber" DESC
```

This list as a web page: https://openairdocs.org/ntsb?engine=41525&year=1991

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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.