# NTSB LAX91DUJ03: Air Tractor AT-302, N4441S, Somerton, AZ, November 16, 1990

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Final report
- Date: November 15, 1990, 20:30 local (Nov 16, 1990, 03:30 UTC)
- Place: Somerton, AZ
- Coordinates: 32.530483, -114.710784 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=32.5305&lon=-114.7108&mi=10
- Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 1 uninjured
- Status: Completed, report November 23, 1992
- Report: Approved by Office Director
- NTSB case key (mKey): 26952
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX91DUJ03
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/26952/pdf
- Page: https://openairdocs.org/ntsb/LAX91DUJ03

## Probable cause

THE FAILURE OF THE NUMBER 3 EXHAUST VALVE WHICH LED TO AN ENGINE FAILURE AND SUBSEQUENT CRASH LANDING.

## Sequence of events

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

- Loss of engine power(partial) - mech failure/malf, maneuvering - aerial application
  - engine assembly,valve,exhaust - cracked (cause)
- In flight collision with terrain/water, descent - emergency

## Analysis

THE PILOT EXPERIENCED A LOSS OF ENGINE POWER AND COLLIDED WITH THE TERRAIN DURING A SWATH RUN. EXAMINATION OF THE ENGINE REVEALED THE NUMBER 3 EXHAUST VALVE WAS CRACKED. THE ENGINE HAD 266 HOURS SINCE OVERHAUL AND HAD 20 HOURS SINCE THE LAST INSPECTION.

## Aircraft

- Registration: [N4441S](https://openairdocs.org/deregistered/N4441S-2014-10-17), registration cancelled 2014-10-17, S/N 302-0101, built 1977 (OpenAirDocs)
- Reported make and model: Air Tractor AT-302
- Registry model: [Air Tractor AT-302](https://openairdocs.org/model/air-tractor-at-302) (registry code 0390104) (OpenAirDocs)
- Registry engine: [Amateur-built UNKNOWN ENG](https://openairdocs.org/engine/amateur-built-unknown-eng) (registry code 99999) (OpenAirDocs)
- Category: Airplane
- Serial number: 302-0101
- Airframe hours: 4950
- Engines: P&W R-1340 AN1 600 horsepower reciprocating
- Damage: Substantial damage
- Fire: On-Ground
- Flight: Aerial application, Part 137
- Operator: Kottenbrook, Jeffrey L., doing business as Desert Southwest Sprayers
- Registered owner: Jeffrey L Kottenbrook
- Airworthiness certificate: Special, Restricted (Special)
- Last inspection: Annual, March 1, 1990, 20 hours before

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 47; commercial; airplane ratings: single-engine land, multi-engine land, single-engine sea; instrument ratings: airplane; medical: class 2, valid medical--w/ waivers/lim; seat: front; flight hours: 8,300 total, 5,200 in this make and model

## Weather

- Conditions: Visual (VMC), Night/dark
- Wind: calm
- Lowest ceiling: none
- Temperature: 70 °F, dew point 30 °F
- Altimeter: 30.00 inHg

## 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 19901115050889A](https://openairdocs.org/incident/19901115050889A), Nov 15, 1990: Airtrc AT302, Somerton, AZ, Substantial damage. Engine quit on swath run. Nosed over on forced landing. Stuck valve caused cylinder to crack and engine failed.

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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