# NTSB CHI90FA117: Bellanca 8KCAB, N2976R, West Bend, WI, April 24, 1990

- Type: NTSB accident investigation
- Classification: Accident · Fatal · Field investigation · Final report
- Date: April 24, 1990, 13:50 local (18:50 UTC)
- Place: West Bend, WI
- Coordinates: 43.419204, -88.17955 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=43.4192&lon=-88.1796&mi=10
- Phase of flight: [Other](https://openairdocs.org/ntsb-phases/800) (OpenAirDocs' grouping)
- Highest injury: Fatal
- Injuries: 2 fatal
- Status: Completed, report January 23, 1992
- Report: Approved by Office Director
- Safety recommendations: Yes
- NTSB case key (mKey): 14528
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CHI90FA117
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/14528/pdf
- Page: https://openairdocs.org/ntsb/CHI90FA117

## Probable cause

INFLIGHT FAILURE OF THE RIGHT WING STRUT-TO-SPAR ATTACHMENT FITTING DUE TO FATIGUE INITIATED BY IMPROPER WELDING TECHNIQUES INVOLVING INADEQUATE POST-WELD COOLING CONTROL.

## Sequence of events

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

- Airframe/component/system failure/malfunction, other
  - wing,wing attachment fitting - fatigue (cause)
  - inadequate quality control, manufacturer (cause)
  - wing,wing attachment fitting - failure,total (cause)
  - wing - separation (cause)
- In flight collision with terrain/water, descent - uncontrolled

## Analysis

THE RIGHT WING SEPARATED FROM THE AIRCRAFT DURING AN INSTRUCTIONAL AEROBATIC FLIGHT. METALLURGICAL EXAMINATION REVEALED THAT THE RIGHT WING'S LIFT STRUT-TO-WING SPAR ATTACHMENT FITTING HAD FAILED DUE TO FATIGUE PROGRESSION IN BOTH SIDE PLATES OF THE FITTING. THE INITIATION AREAS WERE IMMEDIATELY ADJACENT TO THE ENDS OF TWO WELDS. IN THE WELD HEAT AFFECTED ZONE, THE MICROSTRUCTURE TRANSITIONED FROM A SPHEROIDIZED PEARLITE REGION NEAR THE BASE METAL INTO A COARSE TEMPERED MARTENSITE REGION ADJACENT TO THE FUSION ZONE.

## Aircraft

- Registration: [N2976R](https://openairdocs.org/deregistered/N2976R-1992-05-19), registration cancelled 1992-05-19, S/N 62480 (OpenAirDocs)
- Reported make and model: BELLANCA 8KCAB
- Registry model: [Bellanca 7KCAB](https://openairdocs.org/model/bellanca-7kcab) (registry code 1220701) (OpenAirDocs)
- Category: Airplane
- Serial number: 624-80
- Airframe hours: 1775
- Engines: LYCOMING AEIO-360-H1A 180 horsepower reciprocating
- Damage: Destroyed
- Flight: Instructional, Part 91
- Operator: Gran-Aire, Inc.
- Airworthiness certificate: Standard, Aerobatic
- Last inspection: Annual, February 26, 1990, 50 hours before
- Departed: MWC, MILWAUKEE, WI

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 47; flight instructor, commercial; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 2, valid medical--w/ waivers/lim; toxicology performed; flight hours: 26,000 total, 4,000 in this make and model, 25,600 as pilot in command, 65 in the last 90 days, 25 in the last 30 days, 5 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 210° at 10 knots
- Visibility: 7 statute miles
- Lowest ceiling: none
- Temperature: 82 °F, dew point 37 °F
- Altimeter: 29.00 inHg
- Observed at: MWC, 15 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 19900424014939A](https://openairdocs.org/incident/19900424014939A), Apr 24, 1990: Bbavia 8KCAB, West Bend, WI, Destroyed, 2 fatal. Right wing separated during aerobatic dual instruction. Forward wing lift strut failed. Service letter issued.

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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