# NTSB LAX90DVA04: Grumman-Schweizer G-164B, N6725K, Buttonwillow, CA, June 8, 1990

- Type: NTSB accident investigation
- Classification: Accident · Serious injuries · Final report
- Date: June 8, 1990, 06:30 local (13:30 UTC)
- Place: Buttonwillow, CA
- Coordinates: 35.429847, -119.490097 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=35.4298&lon=-119.4901&mi=10
- Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping)
- Highest injury: Serious injuries
- Injuries: 1 serious, 1 minor; on the ground: 1 minor
- Status: Completed, report September 4, 1992
- Report: Approved by Office Director
- NTSB case key (mKey): 26558
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX90DVA04
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/26558/pdf
- Page: https://openairdocs.org/ntsb/LAX90DVA04

## Probable cause

FAILURE OF THE #7 CYLINDER DUE TO A PRE-EXISTING CRACK. THE TERRAIN CONDITION WAS A RELATED FACTOR.

## Sequence of events

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

- Loss of engine power(total) - mech failure/malf, maneuvering - aerial application
  - engine assembly,cylinder - cracked (cause)
- Forced landing, descent - emergency
- Nose over, landing
  - terrain condition - none suitable (contributing factor)
  - terrain condition - crop

## Analysis

THE PILOT WAS COMPLETEING AN AERIAL APPLICATION SWATH RUN, WHEN HE HEARD A LOUD BACKFIRE EMANATE FROM THE ENGINE DURING THE PULL-UP. THE ENGINE THEN QUIT RUNNING ALTOGETHER. THE PILOT ATTEMPTED TO MAKE A LANDING ON A DIRT ROAD, BUT LANDED SHORT IN A TOMATO FIELD, AND THE AIRCRAFT NOSED OVER ONTO ITS BACK. EXAMINATION OF THE ENGINE REVEALED THAT THE NUMBER 7 CYLINDER HEAD HAD A CRACK, WHICH EXTENDED FROM THE FORWARD SPARK PLUG BOSS AROUND THE CYLINDER HEAD TO THE REAR SPARK PLUG BOSS. DETAILED EXAMINATION OF THE CRACK SHOWED THAT THE FRACTURE FACE WAS CONTAMINATED BY CARBON DEPOSITS AND LIGHT CORROSION IN THE COARSE AREA OF THE CRACK, INDICATING THAT THE CRACK WAS PRESENT FOR A LENGTHY PERIOD OF TIME PRIOR TO THE ACCIDENT. THE CYLINDER WAS REPORTED TO HAVE ONLY 181 HOURS SINCE OVERHAUL.

## Aircraft

- Registration: [N6725K](https://openairdocs.org/aircraft/N6725K), registered now, S/N 438B, built 1978 (OpenAirDocs)
- Reported make and model: Grumman-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
- Airframe hours: 4894
- Engines: P&W R-1340-AN-1 600 horsepower reciprocating
- Damage: Destroyed
- Fire: On-Ground
- Flight: Aerial application, Part 137
- Operator: Vince Crop Duster, Inc.
- Registered owner: Vince Crop Dusters, Inc
- Airworthiness certificate: Special, Restricted (Special)
- Last inspection: Annual, April 17, 1990, 165 hours before
- Departed: NONE
- Destination: NONE

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 55; commercial; airplane ratings: single-engine land; medical: class 2, valid medical--w/ waivers/lim; seat: center; flight hours: 12,000 total, 3,000 in this make and model, 12,000 as pilot in command, 150 in the last 90 days, 75 in the last 30 days, 5 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 140° at 5 knots
- Visibility: 20 statute miles
- Lowest ceiling: none
- Temperature: 70 °F, dew point 59 °F
- Altimeter: 29.00 inHg
- Observed at: BFL, 12 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 19900608019559A](https://openairdocs.org/incident/19900608019559A), Jun 8, 1990: Scwzer G164B, Buttonwillow, CA, Destroyed. NR7 cylinder failed on the radial engine. Lost power and impacted ground very hard and burned. Was on a turn around

## 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 WPR11CA128](https://openairdocs.org/ntsb/WPR11CA128), Feb 5, 2011: Schweizer G-164B (N6725K), Buttonwillow, CA, substantial damage. Probable cause: The pilot's failure to maintain clearance from an irrigation vent pipe.
- [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

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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