# NTSB LAX92FA149: Ayres S2R-T34, N59SK, Bakersfield, CA, March 23, 1992

- Type: NTSB accident investigation
- Classification: Accident · Serious injuries · Field investigation · Final report
- Date: March 23, 1992, 14:30 local (22:30 UTC)
- Place: Bakersfield, CA
- Coordinates: 35.340118, -119.069786 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=35.3401&lon=-119.0698&mi=10
- Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping)
- Highest injury: Serious injuries
- Injuries: 1 serious
- Status: Completed, report September 17, 1993
- Report: Approved by Office Director
- Safety recommendations: Yes
- NTSB case key (mKey): 27412
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX92FA149
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/27412/pdf
- Page: https://openairdocs.org/ntsb/LAX92FA149

## Probable cause

A CATASTROPHIC WING SPAR FAILURE PRECIPITATED BY HIDDEN CORROSION AND THE RESTRICTED VIEW OF THE AREA OF CORROSION BY THE AIRPLANE'S WING STRUCTURE.

## Sequence of events

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

- Airframe/component/system failure/malfunction, maneuvering - aerial application
  - wing,spar - corroded (cause)
  - maintenance,inspection - restricted (cause)
  - wing,spar - failure,partial (cause)
- In flight collision with terrain/water, maneuvering - aerial application

## Analysis

WITNESSES OBSERVED PARTS FALL FROM THE AIRPLANE DURING THE INITIAL SWATH RUN. AS THE AIRPLANE ENTERED A RIGHT CLIMBING TURN TO NEGOTIATE 30-FT HIGH TELEPHONE WIRES, IT ENTERED INTO A LEFT WING-OVER AND NOSED DOWN INTO THE GROUND. THE LEFT WING SPAR HAD SEPARATED, AND THE FRACTURED SURFACES DISCLOSED EVIDENCE OF CORROSION. THE 16-FT LONG LOWER STEEL SPAR CAP HAD SEPARATED FROM THE ALUMINUM WING SPAR WEB ALONG THE ENTIRE LENGTH. FRACTURE SURFACES IN THE HUCK LOCKBOLT TYPE FASTENERS ON THE SPAR DISCLOSED EVIDENCE OF CORROSION. THE AREA OF THE HUCK LOCKBOLT CORROSION IS NOT NOTICEABLE BY VISUAL INSPECTION. THE CORROSION IS MASKED BY THE STEEL SPAR CAP. NONE OF THE HUCK LOCKBOLT COLLARS WERE LOOSE OR MISSING. THE AIRPLANE HAD COMPLETED AN 100-HR INSPECTION 71 HRS BEFORE THE ACCIDENT. AT THE TIME OF THE INSPECTION THERE WERE NO DISCREPANCIES NOTED WITH THE WING SPAR.

## Aircraft

- Registration: [N59SK](https://openairdocs.org/deregistered/N59SK-2013-04-24), registration cancelled 2013-04-24, S/N T34-008, built 1979 (OpenAirDocs)
- Reported make and model: AYRES S2R-T34
- Registry model: [Ayres S2R-T34](https://openairdocs.org/model/ayres-s2r-t34) (registry code 0970106) (OpenAirDocs)
- Registry engine: [U/A Canada PT6A series](https://openairdocs.org/engine/u-a-canada-pt6a-series) (registry code 61508, turbo-prop) (OpenAirDocs)
- Category: Airplane
- Serial number: T34-008
- Airframe hours: 10781
- Engines: P&W PT6-34 750 horsepower turbo prop
- Damage: Destroyed
- Flight: Aerial application, Part 137
- Operator: Old River Crop Dusting, Inc
- Registered owner: Old River Crop Dusting, Inc
- Airworthiness certificate: Special, Restricted (Special)
- Last inspection: 100 hour, March 9, 1992, 71 hours before

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 48; commercial; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 2, valid medical--no waivers/lim.; seat: front; flight hours: 22,000 total, 14,000 in this make and model, 21,500 as pilot in command, 230 in the last 90 days, 135 in the last 30 days, 2 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: calm
- Visibility: 20 statute miles
- Lowest ceiling: none

## 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 19920323007319A](https://openairdocs.org/incident/19920323007319A), Mar 23, 1992: Ayres S2RT34RESTD, Bakersfield, CA, Destroyed. Left wing spar broke due corrosion during ag turn around. Huck bolts securing steel spar cap heavily corroded.

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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