# NTSB LAX91LA256: Weaver WACO-ASO, N4W, Montague, CA, June 9, 1991

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: June 9, 1991, 15:00 local (22:00 UTC)
- Place: Montague, CA
- Coordinates: 41.760101, -122.390304 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=41.7601&lon=-122.3903&mi=10
- Phase of flight: [Takeoff](https://openairdocs.org/ntsb-phases/300) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 2 uninjured
- Status: Completed, report December 4, 1992
- Report: Approved by Office Director
- NTSB case key (mKey): 27242
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX91LA256
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/27242/pdf
- Page: https://openairdocs.org/ntsb/LAX91LA256

## Probable cause

FAILURE OF THE PILOT TO MAINTAIN DIRECTIONAL CONTROL OF THE AIRPLANE AND IMPROPER USE OF THE BRAKES.

## Sequence of events

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

- Loss of control - on ground/water, takeoff - roll/run
  - landing gear,tailwheel - vibration
  - directional control - not maintained, pilot in command (cause)
  - brakes(normal) - improper use of, pilot in command (cause)
  - operation with known deficiencies in equipment - intentional, pilot in command
- On ground/water encounter with terrain/water, takeoff - roll/run
  - terrain condition - soft
- Nose over, takeoff - roll/run

## Analysis

THE CERTIFICATED PILOT AND ONE PASSENGER WERE DEPARTING THE AIRPORT FOLLOWING A REFUELING STOP ON A CROSS COUNTRY FLIGHT FROM A VINTAGE AIRPLANE SHOW.  DURING THE TAKEOFF ROLL, THE PILOT REPORTED THAT THE AIRPLANE DEVELOPED A VIBRATION IN THE TAILWHEEL.  THE AIRPLANE DRIFTED OFF THE LEFT SIDE OF THE RUNWAY AND THE PILOT ATTEMPTED TO CORRECT WITH RIGHT RUDDER AND RIGHT BRAKE.  THE PILOT APPLIED POWER AND THE AIRPLANE BECAME AIRBORNE MOMENTARILY.  THE AIRPLANE THEN SETTLED AND THE RIGHT WHEEL CONTACTED THE RUNWAY SURFACE WITH THE BRAKE LOCKED.  THE AIRPLANE SWERVED TO THE RIGHT, THE LEFT LANDING GEAR COLLAPSED AND THE AIRPLANE SKIDDED OFF THE RIGHT SIDE OF THE RUNWAY AND NOSED OVER.  A WITNESS REPORTED HEARING SCRAPING AND SQUEAKING NOISES EMANATING FROM THE AIRPLANE PRIOR TO TAKEOFF AND MENTIONED IT TO THE PILOT.  THE PILOT REPLIED THAT HE HAD 'SOFT BRAKES' IN THE PAST.  THE PILOT ALSO REPORTED THAT THE TAILWHEEL BEARING WAS FOUND SHATTERED BUT THIS HAD OCCURRED DURING THE INITIAL TRIP TO THE VINTAGE AIRSHOW.

## Aircraft

- Registration: [N4W](https://openairdocs.org/aircraft/N4W), registered now, S/N X3101 (OpenAirDocs)
- Reported make and model: WEAVER WACO-ASO
- Registry model: [Waco ASO](https://openairdocs.org/model/waco-aso) (registry code 9601202) (OpenAirDocs)
- Registry engine: [Continental R670-SERIES series](https://openairdocs.org/engine/continental-r670-series-series) (registry code 17016, reciprocating) (OpenAirDocs)
- Category: Airplane
- Serial number: 3101
- Airframe hours: 7533
- Engines: CONTINENTAL W670-6A 220 horsepower reciprocating
- Damage: Substantial damage
- Flight: Personal, Part 91
- Operator: Willard Detour
- Registered owner: Willard Detour
- Airworthiness certificate: Standard, Normal
- Last inspection: Annual, December 20, 1990, 34 hours before
- Destination: 61S, COTTAGE GROVE, OR
- Airport: 105, Montague, runway 32, 3,360 × 50 ft, asphalt

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 71; commercial; airplane ratings: single-engine land; medical: class 2, valid medical--w/ waivers/lim; seat: rear; flight hours: 2,819 total, 1,198 in this make and model, 2,551 as pilot in command, 21 in the last 90 days, 17 in the last 30 days, 4 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 280° at 7 knots
- Visibility: 50 statute miles
- Lowest ceiling: none
- Temperature: 90 °F
- Altimeter: 29.00 inHg
- Observed at: S1Y, 5 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 19910609020489A](https://openairdocs.org/incident/19910609020489A), Jun 9, 1991: Waco ASO, Montague, CA, Substantial damage. Tail wheel vibrated. Lost directional control. Right main clogged with grass leaving runway. Nosed over.

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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