# NTSB SEA89FA099: Cushing 4, N5321U, Mansfield, WA, June 4, 1989

- Type: NTSB accident investigation
- Classification: Accident · Fatal · Field investigation · Final report
- Date: June 4, 1989, 13:15 local (20:15 UTC)
- Place: Mansfield, WA
- Coordinates: 47.890098, -119.5009 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=47.8901&lon=-119.5009&mi=10
- Phase of flight: [Unknown](https://openairdocs.org/ntsb-phases/990) (OpenAirDocs' grouping)
- Highest injury: Fatal
- Injuries: 2 fatal
- Status: Completed, report June 26, 1992
- Report: Approved by Office Director
- NTSB case key (mKey): 40919
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=SEA89FA099
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/40919/pdf
- Page: https://openairdocs.org/ntsb/SEA89FA099

## Probable cause

FAILURE OF THE LEFT WING MAIN SPAR DUE TO OVERLOAD FOR UNDETERMINED REASONS.

## Sequence of events

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

- Airframe/component/system failure/malfunction, unknown
  - wing,spar - overload (cause)
  - wing,spar - failure,total (cause)
- In flight collision with terrain/water, descent - uncontrolled

## Analysis

THE LEFT WING OF THE HOMEBUILT SEPARATED IN FLIGHT. THE WING MAIN SPAR WAS A HEAVY WOODEN BEAM WITH METAL REINFORCEMENT PLATES BOLTED TO THE FORE AND AFT SURFACES THAT EXTENDED THROUGH THE AIRCRAFT CABIN. THE SPAR WAS FOUND BROKEN ADJACENT TO THE LEFT SIDE OF THE CABIN, THROUGH BOLT HOLES AT THE METAL REINFORCEMENT BRACKETS. THE WOOD SPLINTERS IN THE FRACTURED SPAR WERE BENT TOWARD THE TOP SURFACE OF THE WING. THERE WAS NO EVIDENCE OF FATIGUE CRACKING OR DRY ROTTING.

## Aircraft

- Registration: [N5321U](https://openairdocs.org/deregistered/N5321U-1991-09-20), registration cancelled 1991-09-20, S/N 712 (OpenAirDocs)
- Reported make and model: CUSHING 4
- Registry model: [Cushing Leonard H CUSHING 4](https://openairdocs.org/model/cushing-leonard-h-cushing-4) (registry code 05613FC) (OpenAirDocs)
- Category: Airplane, amateur-built
- Serial number: 7-12
- Engines: GM CORVAIR 110 110 horsepower reciprocating
- Damage: Destroyed
- Flight: Personal, Part 91
- Registered owner: Leonard H. Cushing
- Airworthiness certificate: Special, Experimental (Special)
- Departed: S35, OKANOGAN, WA
- Destination: WA97, BUENA, WA

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 67; commercial; airplane ratings: single-engine sea, single-engine land; medical: class 2, valid medical--w/ waivers/lim; seat: left; toxicology performed; flight hours: 1,009 total

## Weather

- Conditions: Visual (VMC), Day
- Wind: 270° at 13 knots
- Visibility: 30 statute miles
- Lowest ceiling: none
- Temperature: 82 °F, dew point 45 °F
- Altimeter: 30.00 inHg
- Observed at: EAT, 36 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 19890604014309A](https://openairdocs.org/incident/19890604014309A), Jun 4, 1989: Amtr CUSHING, Mansfield, WA, Destroyed, 2 fatal. Wing spar failed near wing root of homebuilt aircraft. No witness to crash.

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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