# NTSB investigations: Lycoming VO-435 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 CHI03FA277](https://openairdocs.org/ntsb/CHI03FA277.md): Bell TH-13T · Light, AR · Accident · Serious injuries · Field investigation · Final report · Aug 21, 2003 · N38CD · Substantial damage
  > The total failure and seizure of the main rotor transmission while in cruise flight leading to the helicopter’s impact with terrain.
- [NTSB LAX03LA236](https://openairdocs.org/ntsb/LAX03LA236.md): Bell 47G-2A · Porterville, CA · Accident · No injuries · Limited investigation · Final report · Jul 20, 2003 · N4774S · Substantial damage
  > Fatigue-induced failure of bolts in the helicopter's rotor drive flange, which resulted in a total loss of torque to the rotor drive shaft.
- [NTSB FTW01LA202](https://openairdocs.org/ntsb/FTW01LA202.md): Hiller UH-12D · Lubbock, TX · Accident · Minor injuries · Limited investigation · Final report · Sep 3, 2001 · N2770 · Substantial damage
  > the failure of the tail rotor drive shaft hanger bearing, which resulted in the separation of the tail rotor drive shaft. A contributing factor was the lack of suitable terrain for the forced landing.
- [NTSB ATL99LA107](https://openairdocs.org/ntsb/ATL99LA107.md): Continental Copters Tomcat MK5A · Camden, AL · Accident · Minor injuries · Limited investigation · Final report · Jul 14, 1999 · N9086T · Substantial damage
  > The failure of the cyclic control rod due to an overstress separation resulting from a material defect (inadequate quality of material) by the manufacturer.
- [NTSB CHI97LA306](https://openairdocs.org/ntsb/CHI97LA306.md): Bell 47 · Pipestone, MN · Accident · Serious injuries · Limited investigation · Final report · Sep 30, 1997 · N9005T · Substantial damage
  > the fracture of the pitch control rod assembly.
- [NTSB FTW97LA264](https://openairdocs.org/ntsb/FTW97LA264.md): Bell 47G-3B-1 · Crossett, AR · Accident · Serious injuries · Limited investigation · Final report · Jul 13, 1997 · N83701 · Substantial damage
  > failure of maintenance personnel to perform an adequate inspection of the fuselage center frame and detect a fatigue fracture of a longeron tube on the upper left side of the center frame, which resulted in a disconnect of the tail rotor drive shaft from the…
- [NTSB SEA95LA227](https://openairdocs.org/ntsb/SEA95LA227.md): Texas Helicopter OH-13E · Yakima, WA · Accident · No injuries · Limited investigation · Final report · Sep 20, 1995 · N38115 · Substantial damage
  > Fatigue failure of the bolt attaching the scissor arm assembly to the pitch control support assembly. The failure of the bolt led to a loss of collective pitch control and reduced rotor RPM.
- [NTSB LAX95LA216](https://openairdocs.org/ntsb/LAX95LA216.md): Bell 47-G5 · Coalinga, CA · Accident · No injuries · Limited investigation · Final report · Jun 18, 1995 · N7923J · Destroyed
  > clutch slippage for undetermined reasons. A factor in the accident was the helicopter's low above ground altitude, which limited the pilot's time and ability to recover main rotor rpm.
- [NTSB FTW95LA239](https://openairdocs.org/ntsb/FTW95LA239.md): Bell 47G-5 · Falfurrias, TX · Accident · No injuries · Limited investigation · Final report · May 30, 1995 · N1502L · Substantial damage
  > Inadvertent installation of an unapproved part (tail rotor gear/drive assembly), that became excessively worn since it did not conform to the manufacturer's specification, resulting in failure of the associated tail rotor bearing (also an unapproved part),…
- [NTSB CHI95LA003](https://openairdocs.org/ntsb/CHI95LA003.md): Bell 47G2 · Decatur, IL · Accident · Minor injuries · Limited investigation · Final report · Oct 3, 1994 · N5193B · Substantial damage
  > the failure of the roller springs in the freewheeling unit of the transmission which caused the unit to disengage.
- [NTSB DEN93LA091](https://openairdocs.org/ntsb/DEN93LA091.md): Continental Copters Tomcat MK5A · Duson, LA · Accident · No injuries · Limited investigation · Final report · Jul 30, 1993 · N9014T · Substantial damage
  > Failure of the transmission mast bearing, resulting in oil contamination and subsequent blockage of the internal oil ports and passages. Factors were: total loss of collective control and partial loss of cyclic control.
- [NTSB CHI92LA137](https://openairdocs.org/ntsb/CHI92LA137.md): Bell 47-G2A · Dousman, WI · Accident · Serious injuries · Limited investigation · Final report · Apr 30, 1992 · N52HB · Substantial damage
  > The in-flight loss of the swash plate drive link bolt which allowed the swash plate drive assembly to disconnect.
- [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 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 MKC90LA144](https://openairdocs.org/ntsb/MKC90LA144.md): Bell 47D-1 · Fair Oaks, AR · Accident · Minor injuries · Limited investigation · Final report · Jul 12, 1990 · N8117 · Substantial damage
  > Tail rotor cable disengagement due to inadequate maintenance.
- [NTSB MIA89LA221](https://openairdocs.org/ntsb/MIA89LA221.md): Continental Copters Tomcat MK6C · Quitman, MS · Accident · Serious injuries · Limited investigation · Final report · Aug 14, 1989 · N9085T · Destroyed
  > Failure of the tail boom attachment.
- [NTSB LAX88DUG07](https://openairdocs.org/ntsb/LAX88DUG07.md): Bell 47G-5A · Perris, CA · Accident · No injuries · Final report · Sep 18, 1988 · N4099G · Substantial damage
  > On liftoff, tail rotor control was lost and helicopter spun with main rotor striking terrain. Investigation revealed fatigue failure of engine mounting cage. The eng basket had failed and allowed the t/r drive shaft to pull out of the coupling. The basket had…
- [NTSB FTW88LA008](https://openairdocs.org/ntsb/FTW88LA008.md): Bell 47G-2 · Lapra, TX · Accident · No injuries · Limited investigation · Final report · Oct 20, 1987 · N8403E · Substantial damage
  > Upon entering a bank approx. 80 to 100 ft. off the ground, the aircraft experienced a power loss with vibration. During autorotation the aircraft contacted a tree causing substantial damage. Examination of the wreckage found the transmission clutch assembly…
- [NTSB CHI86FER11](https://openairdocs.org/ntsb/CHI86FER11.md): Bell 47G-5 · Brooten, MN · Accident · Serious injuries · Final report · Jun 17, 1986 · N8122J · Destroyed
  > According to the pilot, the helicopter collective control failed to respond to a climb input to level off after a descent for an agricultural swath run. Fire and impact damage to the helicopter was extensive, however one broken rod end in the collective…
- [NTSB SEA86LA089](https://openairdocs.org/ntsb/SEA86LA089.md): Hiller 12E · Walla Walla, WA · Accident · No injuries · Limited investigation · Final report · Mar 30, 1986 · N87595 · Destroyed
  > A catastrophic failure of the planetary gear of the transmission occurred about 51 flight hours after overhaul. During forced landing a hard landing occurred severing the tail boom. A fire then erupted.
- [NTSB MIA85LA223](https://openairdocs.org/ntsb/MIA85LA223.md): Bell 47G-2 · Ochopee, FL · Accident · No injuries · Limited investigation · Final report · Aug 1, 1985 · N88AR · Substantial damage
  > The plt stated that he dropped his passenger off at a water station in the everglades, water taxied away from the station, accellerated up to 3100 RPM & just before he added collective pitch the transmission ass'y departed the helicopter, it rolled to the…
- [NTSB MIA85LA207](https://openairdocs.org/ntsb/MIA85LA207.md): Quinn EL Tomcat MK-5A · Blakley, GA · Accident · No injuries · Limited investigation · Final report · Jul 4, 1985 · N8429 · Substantial damage
  > While en route to reposition the helicopter to another farm, the eng lost power. The plt reported that during an autorotation, the main rotor lost some RPM as he stretched his glide to avoid a fence. As the helicopter touched down on uneven terrain, the main…
- [NTSB ANC83FA092](https://openairdocs.org/ntsb/ANC83FA092.md): Bell B47G-2 · Anchorage, AK · Accident · No injuries · Field investigation · Final report · Jun 7, 1983 · N6140C · Substantial damage
  > The helicopter experienced a tail rotor strike during a hard landing with a door open. According to the student pilot who is a commercial pilot working on an add-on helicopter rating, the left cockpit door unlatched and partially opened on the downwind leg…
- [NTSB MKC82DA151](https://openairdocs.org/ntsb/MKC82DA151.md): Bell 47G-2A · Washington, IA · Accident · No injuries · Final report · Aug 22, 1982 · N73205 · Substantial damage
  > The helicopter was being air taxied to the refueling location when it crashed. The pilot said he had lifted off and was about 6 ft AGL with about 20 KTS forward speed when he suddenly felt a snap and the cyclic went full left. The helicopter became…
- [NTSB CHI82DA198](https://openairdocs.org/ntsb/CHI82DA198.md): Bell 47G-5A · New Philadelphi, OH · Accident · Minor injuries · Final report · Jun 1, 1982 · N2988W · Destroyed
  > While patrolling a powerline, the pilot heard a loud noise, similar to a gunshot, which seemed to come from directly behind the firewall. Immediately after that, the helicopter started to pitch up and roll to the right. He reported that the helicopter reached…

## 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 ('41525')
    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=41525&occurrence=130

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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.