# NTSB CHI91DCD01: Heal SONERAI-I, N4227N, Davenport, IA, June 23, 1991

- Type: NTSB accident investigation
- Classification: Accident · Fatal · Final report
- Date: June 23, 1991, 15:48 local (20:48 UTC)
- Place: Davenport, IA
- Coordinates: 41.520401, -90.569 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=41.5204&lon=-90.5690&mi=10
- Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping)
- Highest injury: Fatal
- Injuries: 1 fatal
- Status: Completed, report July 29, 1992
- Report: Approved by Office Director
- NTSB case key (mKey): 14795
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CHI91DCD01
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/14795/pdf
- Page: https://openairdocs.org/ntsb/CHI91DCD01

## Probable cause

FAILURE OF THE WING SPAR STRAPS, AS THE AIRCRAFT WAS BEING MANEUVERED AROUND A PYLON IN AN AIR RACE.

## Sequence of events

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

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

## Analysis

THE PLT WAS PARTICIPATING IN A PYLON AIR RACE FOR FORMULA V RACERS.  ABT HALF WAY THRU THE RACE, AS HE WAS MNVRG PAST THE #2 PYLON, THE LEFT WING BGN TO SEPARATE. THE WING THEN FOLDED OVR THE TOP OF THE ACFT. THE WING & PIECES OF THE CANOPY FELL TO THE GND. AS THE WING SEPD, THE ACFT BGN A VIOLENT ROLL & FLWD A TRAJECTORY PATH TO THE GND. INV REVEALED THE INNER PORTION OF EACH WING WAS DESIGNED WITH BOX SPAR CONSTRUCTION, SECURED TO A FUSELAGE CARRY-THRU CONFIGURATION. THE OUTER WING SPARS CONSISTED OF A SERIES OF UPPER & LOWER STRAPS. THESE WERE SECURED TO A SHEET METAL WEB WITH RIVETS. THE 4 LOWER SPAR STRAPS HAD FAILED; 2 HAD FAILED AT THE 1ST RIVET HOLE OUTBOARD OF THE BOX SPAR CONFIGURATION; ONE FAILED AT THE 1ST BOLT HOLE NEAR THE OUTBOARD END OF THE BOX SPAR & THE 4TH FAILED FLUSH WITH THE OUTBOARD END OF THE BOX SPAR.

## Aircraft

- Registration: [N4227N](https://openairdocs.org/deregistered/N4227N-1991-11-08), registration cancelled 1991-11-08, S/N 210 (OpenAirDocs)
- Reported make and model: HEAL SONERAI-I
- Registry model: [Heal David B SONERAI-I](https://openairdocs.org/model/heal-david-b-sonerai-i) (registry code 05659L9) (OpenAirDocs)
- Category: Airplane, amateur-built
- Serial number: 210
- Engines: VOLKSWAGEN CONVERSION 60 horsepower reciprocating
- Damage: Destroyed
- Flight: Part 91
- Operator: R.W. Leonard
- Departed: DVN
- Airport: DVN, Davenport Muni

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 46; commercial; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 2, valid medical--no waivers/lim.; toxicology performed; flight hours: 1,000 total, 100 in this make and model

## Weather

- Conditions: Visual (VMC), Day
- Wind: 130° at 7 knots
- Visibility: 8 statute miles
- Lowest ceiling: none
- Temperature: -0 °F, dew point -0 °F
- Observed at: DVN, 1 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 19910623023209A](https://openairdocs.org/incident/19910623023209A), Jun 23, 1991: Amtrmo SONERAI, Davenport, IA, Destroyed, 1 fatal. Wing spar straps pulled loose during plyon turn in air race causing loss of wing and uncontrolled ground impact.

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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