# NTSB WPR11CA128: Schweizer G-164B, N6725K, Buttonwillow, CA, February 5, 2011

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Data collection · Final report
- Date: February 5, 2011, 09:30 local (17:30 UTC)
- Place: Buttonwillow, CA
- Coordinates: 35.455833, -119.580001
- Nearby events: https://openairdocs.org/map.md?lat=35.4558&lon=-119.5800&mi=10
- Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping)
- Defining event: [Landing-landing roll: Nose over/nose down](https://openairdocs.org/ntsb-events/096)
- Highest injury: No injuries
- Injuries: 1 uninjured
- Status: Completed, report June 8, 2011
- Report: Approved by Office Director
- NTSB office: Western Pacific Region
- Parties: Federal Aviation Administration FSDO
- NTSB case key (mKey): 78303
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR11CA128
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/78303/pdf
- NTSB docket: https://data.ntsb.gov/Docket?ProjectID=78303
- Page: https://openairdocs.org/ntsb/WPR11CA128

## Probable cause

The pilot's failure to maintain clearance from an irrigation vent pipe.

## Findings

NTSB's coded findings; those marked are part of the probable cause.

- [Terrain](https://openairdocs.org/ntsb-findings/03021000): Environmental issues › Physical environment · Contributed to outcome; cases with it: [Grumman Acft ENG Cor-Schweizer G-164B, 7 cases](https://openairdocs.org/ntsb-findings/03021000/cases.md?model=3952802), [All aircraft, 267 cases](https://openairdocs.org/ntsb-findings/03021000/cases.md)
- [Attention/monitoring: monitoring environment](https://openairdocs.org/ntsb-findings/02021545): Personnel issues › Psychological · Pilot (probable cause); cases with it: [Grumman Acft ENG Cor-Schweizer G-164B, 11 cases](https://openairdocs.org/ntsb-findings/02021545/cases.md?model=3952802), [All aircraft, 809 cases](https://openairdocs.org/ntsb-findings/02021545/cases.md)
- [Object/animal/substance: pole](https://openairdocs.org/ntsb-findings/03022010): Environmental issues › Physical environment · Response/compensation (probable cause); cases with it: [Grumman Acft ENG Cor-Schweizer G-164B, 3 cases](https://openairdocs.org/ntsb-findings/03022010/cases.md?model=3952802), [All aircraft, 142 cases](https://openairdocs.org/ntsb-findings/03022010/cases.md)

## Sequence of events

The events NTSB coded, in order, by phase of flight. The defining event best describes what happened.

- [Maneuvering-low-alt flying: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Grumman Acft ENG Cor-Schweizer G-164B, 21 cases](https://openairdocs.org/ntsb-events/470/sequence.md?model=3952802), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md)
- [Emergency descent: Off-field or emergency landing](https://openairdocs.org/ntsb-events/440); cases with it: [Grumman Acft ENG Cor-Schweizer G-164B, 17 cases](https://openairdocs.org/ntsb-events/440/sequence.md?model=3952802), [All aircraft, 3,365 cases](https://openairdocs.org/ntsb-events/440/sequence.md)
- [Landing-landing roll: Nose over/nose down](https://openairdocs.org/ntsb-events/096) (defining event); cases with it: [Grumman Acft ENG Cor-Schweizer G-164B, 19 cases](https://openairdocs.org/ntsb-events/096/sequence.md?model=3952802), [All aircraft, 2,287 cases](https://openairdocs.org/ntsb-events/096/sequence.md)

## Analysis

The pilot stated that he was making a low aerial application pass over a field, dispensing smoke to determine wind direction and velocity. The airplane struck a 20-foot-high irrigation vent pipe, which was located in the field that he was working. He proceeded straight ahead and attempted a forced landing on a dirt road immediately next to the field because the engine was losing power. Upon touching down, the right main wheel encountered soft dirt and the airplane nosed over inverted, bending the engine mount and wrinkling the fuselage and vertical stabilizer.

## Factual narrative

The aerial application pilot stated that he was making a low pass over a field, dispensing smoke, to determine wind direction and velocity. The airplane struck a 20-foot-high irrigation vent pipe, which was located in the field that he was working. He proceeded straight ahead and attempted a forced landing on a dirt road immediately next to the field because the engine was losing power. Upon touching down, the right main wheel got into some soft dirt and the airplane nosed over inverted. The engine mount was bent, and the fuselage and vertical stabilizer were wrinkled.

## Aircraft

- Registration: [N6725K](https://openairdocs.org/aircraft/N6725K), registered now, S/N 438B, built 1978 (OpenAirDocs)
- Reported make and model: SCHWEIZER G-164B
- Registry model: [Grumman Acft ENG Cor-Schweizer G-164B](https://openairdocs.org/model/grumman-acft-eng-cor-schweizer-g-164b) (registry code 3952802) (OpenAirDocs)
- Registry engine: [Pratt & Whitney R1340 series](https://openairdocs.org/engine/pratt-whitney-r1340-series) (registry code 52016, reciprocating) (OpenAirDocs)
- Category: Airplane
- Serial number: 438B
- Engines: Pratt & Whitney R-1340 600 horsepower reciprocating
- Damage: Substantial damage
- Flight: Aerial application, Part 137
- Operator: Slikker Flying Service Inc.
- Registered owner: Slikker Flying Service Inc.
- Airworthiness certificate: Special, Restricted (Special)
- Departed: Priv, Buttonwillow, CA
- Destination: Priv, Buttonwillow, CA
- Flight plan: Unknown

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 67; injuries: none; commercial; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 2, with waivers/limitations; last flight review April 16, 2010; seat: center; flight hours: 17,870 total, 8,371 in this make and model, 17,620 as pilot in command, 80 in the last 90 days, 25 in the last 30 days, 1 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Visibility: 7 statute miles
- Lowest ceiling: none
- Temperature: 52 °F, dew point 39 °F
- Altimeter: 30.26 inHg
- Observed at: BFL

## 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 20110205002429A](https://openairdocs.org/incident/20110205002429A), Feb 5, 2011: Grumman Acf G-164B, Buttonwillow, CA, Substantial damage. On 02-05-2011, 9.30AM (local) an aerial applicator , while conducting an aerial application operation, hit a standpipe (irrigation pipe) with its propeller.…

## Other investigations on N6725K (3)

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.

- [NTSB LAX90DVA04](https://openairdocs.org/ntsb/LAX90DVA04), Jun 8, 1990: Grumman-Schweizer G-164B (N6725K), Buttonwillow, CA, destroyed. Probable cause: FAILURE OF THE #7 CYLINDER DUE TO A PRE-EXISTING CRACK. THE TERRAIN CONDITION WAS A RELATED FACTOR.
- [NTSB LAX87DVA10](https://openairdocs.org/ntsb/LAX87DVA10), Jul 29, 1987: Grumman G-164B (N6725K), Taft, CA, substantial damage
- [NTSB OAK78DVG83](https://openairdocs.org/ntsb/OAK78DVG83), Sep 20, 1978: Grumman G-164B (N6725K), Robbins, CA, substantial damage

## Docket (1 files)

The files NTSB released with the investigation on March 24, 2011, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=78303. 431 KB in all.

- Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 431 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40345582&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF

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.

---
OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.