# NTSB LAX91LA254: Cullen/Roth Falcon XP, N9939M, Sebastopal, CA, June 8, 1991

- Type: NTSB accident investigation
- Classification: Accident · Serious injuries · Limited investigation · Final report
- Date: June 8, 1991, 10:49 local (17:49 UTC)
- Place: Sebastopal, CA
- Coordinates: 38.399063, -122.859596 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=38.3991&lon=-122.8596&mi=10
- Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping)
- Highest injury: Serious injuries
- Injuries: 1 serious
- Status: Completed, report December 4, 1992
- Report: Approved by Office Director
- NTSB case key (mKey): 27240
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX91LA254
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/27240/pdf
- Page: https://openairdocs.org/ntsb/LAX91LA254

## Probable cause

THE STRUCTURAL FAILURE OF THE AIRPLANE'S CANARD WING.  CONTRIBUTING FACTORS WHICH RELATED TO THE ACCIDENT WERE THE PILOT'S PERFORMANCE OF AN ADJUSTMENT TO THE RIGGING OF HIS AIRPLANE WHICH DETERIORATED ITS FLIGHT CHARACTERISTICS.

## Sequence of events

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

- Loss of control - in flight, maneuvering
  - canard (cause)
  - maintenance,adjustment - performed, pilot in command (contributing factor)
  - aircraft performance - deteriorated (contributing factor)
  - stall/spin - inadvertent, pilot in command
- Airframe/component/system failure/malfunction, descent - uncontrolled
  - canard - failure,total (cause)

## Analysis

THE PILOT REPORTED THAT HE HAD MODIFIED THE RIGGING OF HIS EXPERIMENTAL CATEGORY AIRPLANE'S CANARD WING, AND ALSO PERFORMED OTHER ADJUSTMENTS TO THE AIRPLANE.  THE PILOT INTENDED TO EVALUATE THE PERFORMANCE OF HIS MODIFIED AMATEUR BUILT AIRPLANE DURING THE TEST FLIGHT.  THE PILOT CLIMBED TO 5000 FEET AGL, SLOWED TO 30 MPH AND ATTEMPTED TO TURN LEFT.  THE AIRPLANE STALLED, ENTERED A SPIN AND THE WING FAILED.

## Aircraft

- Registration: [N9939M](https://openairdocs.org/deregistered/N9939M-1992-02-26), registration cancelled 1992-02-26, S/N 600203 (OpenAirDocs)
- Reported make and model: CULLEN/ROTH FALCON XP
- Registry model: [Cullen/Roth FALCON XP](https://openairdocs.org/model/cullen-roth-falcon-xp) (registry code 05658TA) (OpenAirDocs)
- Category: Airplane, amateur-built
- Serial number: 600203
- Engines: BOMBARDIER ROTAX 503 50 horsepower reciprocating
- Damage: Destroyed
- Flight: Part 91
- Operator: William E. Cullen
- Airworthiness certificate: Special, Experimental (Special)
- Last inspection: Unknown, January 2, 2000
- Departed: O01, SANTA ROSA, CA

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 52; private; airplane ratings: single-engine land; medical: class 3, valid medical--w/ waivers/lim; flight hours: 252 total, 124 in this make and model, 183 as pilot in command

## Weather

- Conditions: Visual (VMC), Day
- Wind: 180° at 5 knots
- Visibility: 15 statute miles
- Lowest ceiling: 25,000 ft broken

## 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 19910608020659A](https://openairdocs.org/incident/19910608020659A), Jun 8, 1991: Amtrat FALCONXP, Sebastapol, CA, Destroyed. Test flight to check stall speed on modified canard. Snapped into spin. Recovered. Broke canard elevator. Crashed.

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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