# NTSB MIA90FA190: Ayres S2R-T34, N4017B, Thornton, MS, September 26, 1990

- Type: NTSB accident investigation
- Classification: Accident · Fatal · Field investigation · Final report
- Date: September 26, 1990, 09:14 local (14:14 UTC)
- Place: Thornton, MS
- Location: 33.0793° N, 90.3226° W: Placed by OpenAirDocs: center of Thornton, MS, within about 6 miles (OpenAirDocs)
- Nearby events: https://openairdocs.org/map.md?lat=33.0793&lon=-90.3226&mi=10
- Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping)
- Highest injury: Fatal
- Injuries: 1 fatal
- Status: Completed, report November 9, 1992
- Report: Approved by Office Director
- NTSB case key (mKey): 32568
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=MIA90FA190
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/32568/pdf
- Page: https://openairdocs.org/ntsb/MIA90FA190

## Probable cause

THE IMPROPER DRILLING OF A HOLE IN THE SPAR CAP BY A MECHANIC RESULTING IN THE INITIATION OF FATIGUE CRACKING IN THE SPAR CAP AND SUBSEQUENT FAILURE OF THE SPAR CAP AND INFLIGHT SEPARATION OF THE WING.

## 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
  - maintenance,major alteration - improper, company maintenance personnel (cause)
  - wing,spar - fatigue (cause)
  - maintenance,inspection - not possible, company maintenance personnel
  - wing,spar - failure,total (cause)
- In flight collision with terrain/water, descent - uncontrolled
  - terrain condition - crop

## Analysis

AIRPLANE EXPERIENCED SEPARATION OF RIGHT WING WHILE PULLING UP FROM AGRICULTURAL SPRAYING RUN. WING SEPARATED DUE TO FATIGUE FAILURE OF THE BOTTOM SPAR CAP WHICH WAS THE RESULT OF A HOLE BEING DRILLED INTO THE CAP. THE HOLE APPEARS TO HAVE BEEN DRILLED INTO THE CAP DURING INSTALLATION OF A WING MOUNTED AIR CONDITIONING COMPRESSOR, SIX YEARS AND 4,130 FLIGHT HOURS BEFORE THE FAILURE. THE AIR CONDITIONING UNIT WAS REMOVED 10 MONTHS LATER AND A PATCH WAS PLACED OVER THE AREA THE HOLE HAD BEEN DRILLED IN SPAR CAP. THE HOLE WOULD NOT HAVE BEEN VISIBLE DURING INSPECTION UNLESS MECHANIC REMOVED PATCH.

## Aircraft

- Registration: [N4017B](https://openairdocs.org/deregistered/N4017B-1997-10-09), registration cancelled 1997-10-09, S/N T34002 (OpenAirDocs)
- Reported make and model: Ayres S2R-T34
- Registry model: [Ayres S2R-T34](https://openairdocs.org/model/ayres-s2r-t34) (registry code 0970106) (OpenAirDocs)
- Category: Airplane
- Serial number: T34-002
- Airframe hours: 5592
- Engines: P&W PT6A-34AG 783 horsepower turbo prop
- Damage: Destroyed
- Flight: Aerial application, Part 137
- Registered owner: George Clanton Dusting Sprayin
- Airworthiness certificate: Special, Restricted (Special)
- Last inspection: Annual, May 7, 1990, 491 hours before
- Departed: 87I, YAZOO CITY, MS

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 66; commercial; airplane ratings: single-engine land; medical: class 2, valid medical--w/ waivers/lim; seat: front; toxicology performed; flight hours: 27,500 total, 3,200 in this make and model, 500 in the last 90 days, 125 in the last 30 days, 1 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 190° at 5 knots
- Visibility: 7 statute miles
- Lowest ceiling: none
- Temperature: 64 °F, dew point 54 °F
- Altimeter: 30.00 inHg
- Observed at: GWO, 25 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 19900926042439A](https://openairdocs.org/incident/19900926042439A), Sep 26, 1990: Ayres S2RT34RESTD, Thorton, MS, Destroyed, 1 fatal. Right wing failed in flight from fatigue cracks around a drill hole in wing spar cap. Patch hid fatigue cracks.

## Other investigations on N4017B (1)

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.

- [NTSB FTW80FQG26](https://openairdocs.org/ntsb/FTW80FQG26), Jun 14, 1980: Ayres S-2R (N4017B), Seminole, TX, substantial damage

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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