# NTSB LAX83FA395: Boeing Vertol BV-107-II, N190CH, Shaver Lake, CA, August 20, 1983

- Type: NTSB accident investigation
- Classification: Accident · Fatal · Field investigation · Final report
- Date: August 20, 1983, 10:05 local (17:05 UTC)
- Place: Shaver Lake, CA
- Coordinates: 37.130237, -119.220848 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=37.1302&lon=-119.2208&mi=10
- Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping)
- Highest injury: Fatal
- Injuries: 2 fatal
- Status: Completed
- Report: Approved by Office Director
- NTSB case key (mKey): 23494
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX83FA395
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/23494/pdf
- Page: https://openairdocs.org/ntsb/LAX83FA395

## Sequence of events

In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf).

- Airframe/component/system failure/malfunction, maneuvering
  - rotor drive system - fatigue (cause)
  - rotor drive system - failure,total (cause)
- Loss of control - in flight, maneuvering
- In flight collision with terrain/water, descent - uncontrolled
  - terrain condition - downhill (contributing factor)
  - terrain condition - rough/uneven (contributing factor)
  - terrain condition - mountainous/hilly (contributing factor)
  - object - tree(s) (contributing factor)

## Analysis

THE ONLY WITNESS, THE HOOKER, WHO GETS LOGS READY FOR TRANSPORT BY THE HELICOPTER, STATED THAT HE HEARD NOISES AND THE ROTOR BLADES BEGAN COMING APART AS THE ACFT STARTED DOWNHILL WITH A LOG. EXAMINATION OF THE WRECKAGE REVEALED THAT #3 SYCHRONIZING SHAFT (BOEING P/N 10703141-13) HAD FAILED A FATIGUE CRACK ORIGINATING AT A RIVET HOLE. THE TOTAL TIME ON THE SHAFT WAS 17492 HOURS WITH 435 HOURS SINCE OVERHAUL. THE QUALITY OF THE SURFACE FINISH ON THE RIVET HOLES WAS CONSIDERED UNSATISFACTORY IN A POST ACCIDENT LABORATORY EVALUATION. AS A INTERIM MEASURE BOEING VERTOL ARBITRAILY IMPOSED A LIFE OF 8750 HOURS ON ALL SYNCHRONIZING SHAFTS OF THIS TYPE. THIS WAS BASED ON THE LIFE OF THIS FAILED PART. A PROGRAM IS ALSO BEING DEVELOPED TO DO A FLT STRAIN SURVEY ON A BV-107 FOR LOGGING OPERATIONS. THE HOOKER STATED THAT THE LOG BEING LIFTED BY THE ACCIDENT ACFT WEIGHED BETWEEN 8000 AND 9000 POUNDS.

## Aircraft

- Registration: [N190CH](https://openairdocs.org/aircraft/N190CH), registered now, S/N 2002, built 1962 (OpenAirDocs)
- Reported make and model: BOEING VERTOL BV-107-II
- Registry model: [Boeing-Vertol 107-II](https://openairdocs.org/model/boeing-vertol-107-ii) (registry code 1385007) (OpenAirDocs)
- Registry engine: [GE CT58-140-2](https://openairdocs.org/engine/ge-ct58-140-2) (registry code 30129, turbo-shaft) (OpenAirDocs)
- Category: Helicopter
- Serial number: 2002
- Airframe hours: 2392
- Engines: GE CT 581401A 1500 horsepower turbo shaft
- Damage: Destroyed
- Flight: Part 133
- Registered owner: Columbia Helicopters Leasing
- Airworthiness certificate: Standard, Normal
- Last inspection: AAIP, August 18, 1983, 8 hours before
- Departed: SHAVER LAKE, CA
- Flight plan: Company VFR

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 36; airline transport, commercial; airplane ratings: single-engine land; instrument ratings: helicopter; medical: class 2, valid medical--no waivers/lim.; seat: left; toxicology performed; flight hours: 2,422 in this make and model

## Weather

- Conditions: Visual (VMC), Day
- Wind: 250° at 15 knots
- Visibility: 50 statute miles
- Temperature: 61 °F
- Observed at: FAT, 35 nm away

## FAA reports on this event (1)

The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs).

- [Accident 19830820074729A](https://openairdocs.org/incident/19830820074729A), Aug 20, 1983: Boeing 1072, Shaver Lake, CA, Destroyed. #3SYN chronizing shaft failed on lifting a external load. Caused main rotors to collide. Rivet hole fatigue cracks.

From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model.

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