# NTSB DEN08LA125: Air Tractor AT-402B, N61318, Deerfield, KS, July 20, 2008

- Type: NTSB accident investigation
- Classification: Accident · Minor injuries · Limited investigation · Final report
- Date: July 20, 2008, 08:30 local (13:30 UTC)
- Place: Deerfield, KS
- Coordinates: 37.851387, -101.118888
- Nearby events: https://openairdocs.org/map.md?lat=37.8514&lon=-101.1189&mi=10
- Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping)
- Defining event: [Maneuvering-low-alt flying: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341)
- Highest injury: Minor injuries
- Injuries: 1 minor
- Status: Completed, report August 28, 2008
- Report: Approved by Office Director
- Parties: FAA Flight Standards District Office
- NTSB case key (mKey): 68484
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DEN08LA125
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/68484/pdf
- Page: https://openairdocs.org/ntsb/DEN08LA125

## Probable cause

The pilot inadvertently stalling the airplane. Contributing factors in this accident were the pilot intentionally performing low altitude maneuvers (side slips), unporting and starving the engine of fuel, and his initiating a climb at low airspeed.

## Findings

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

- [Performance/control parameters: airspeed](https://openairdocs.org/ntsb-findings/01062010): Aircraft › Aircraft oper/perf/capability · Not attained/maintained (probable cause); cases with it: [Air Tractor AT-402B, 3 cases](https://openairdocs.org/ntsb-findings/01062010/cases.md?model=0390208), [All aircraft, 1,681 cases](https://openairdocs.org/ntsb-findings/01062010/cases.md)
- [Object/animal/substance](https://openairdocs.org/ntsb-findings/03022000): Environmental issues › Physical environment · Not specified; cases with it: [Air Tractor AT-402B, 2 cases](https://openairdocs.org/ntsb-findings/03022000/cases.md?model=0390208), [All aircraft, 224 cases](https://openairdocs.org/ntsb-findings/03022000/cases.md)
- [Fuel system](https://openairdocs.org/ntsb-findings/01022800): Aircraft › Aircraft systems · Not specified (probable cause); cases with it: [Air Tractor AT-402B, 1 case](https://openairdocs.org/ntsb-findings/01022800/cases.md?model=0390208), [All aircraft, 181 cases](https://openairdocs.org/ntsb-findings/01022800/cases.md)
- [Performance/control parameters: climb rate](https://openairdocs.org/ntsb-findings/01062035): Aircraft › Aircraft oper/perf/capability · Not attained/maintained (probable cause); cases with it: [Air Tractor AT-402B, 2 cases](https://openairdocs.org/ntsb-findings/01062035/cases.md?model=0390208), [All aircraft, 265 cases](https://openairdocs.org/ntsb-findings/01062035/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: Fuel starvation](https://openairdocs.org/ntsb-events/191); cases with it: [Air Tractor AT-402B, 1 case](https://openairdocs.org/ntsb-events/191/sequence.md?model=0390208), [All aircraft, 733 cases](https://openairdocs.org/ntsb-events/191/sequence.md)
- [Maneuvering-low-alt flying: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341) (defining event); cases with it: [Air Tractor AT-402B, 1 case](https://openairdocs.org/ntsb-events/341/sequence.md?model=0390208), [All aircraft, 3,820 cases](https://openairdocs.org/ntsb-events/341/sequence.md)
- [Uncontrolled descent: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Air Tractor AT-402B, 13 cases](https://openairdocs.org/ntsb-events/470/sequence.md?model=0390208), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md)

## Analysis

The pilot had noticed a fuel imbalance of almost a quarter of a tank after the previous spray flight. The airplane was then serviced with 40 gallons of Jet A fuel through a single point refueling port. The pilot checked the fuel level again and noted the right tank had approximately 1-1/2 inch more fuel than the left tank, or roughly 1/2 capacity in the left tank and between 1/2 and 2/3 capacity in the right tank. He took off with 375 gallons of chemical mix to spray two corn circular fields. He used a left hand reverse racetrack pattern to spray the two circles. Halfway through the application, he checked the fuel gauges and noted both were reading between 1/4 and 1/2 tank. On his final swath of the field, the pilot climbed over a set of power lines. It was his intention to utilize the southerly wind to drift the spray under the power lines to the edge of the field. He performed a right side slip maneuver (right wing down, left rudder) to spray the west circle, leveled his wings, and repeated the maneuver to spray the east circle. He then initiated a 60-degree bank right climbing turn from a height of about 30 feet. The pilot said that during the climbing turn, "altitude and decrease in airspeed felt normal." He looked out the right side of the airplane to check the spray pattern. When he attempted to level the wings at an altitude between 100 and 150 feet, the right wing "continued to drop followed by the nose." He said the stall warning horn never sounded, and there was no aerodynamic buffet. He opened the throttle completely, but the engine did not respond. The airplane struck a pivotal sprinkler and impacted terrain. It was the pilot's opinion that the engine lost power "due to unporting of fuel from the tank to the engine [induced] by the slip maneuver."

## Factual narrative

On July 20, 2008, approximately 0830 central daylight time, an Air Tractor AT-402B, N61318, registered to and operated by Tri-Rotor Spray & Chemical and piloted by a commercial pilot, was destroyed when it struck a pivotal sprinkler and impacted terrain while maneuvering near Deerfield, Kansas. Visual meteorological conditions prevailed at the time of the accident. The local aerial application flight was being conducted under the provisions of Title 14 Code of Federal Regulations (CFR) Part 137 without a flight plan. The pilot, the sole occupant aboard, sustained minor injuries. The flight originated approximately 0800 from Lakin Municipal Airport (36K), Lakin, Kansas.

According to the pilot's accident report, he had noticed a fuel imbalance of almost a quarter of a tank after the previous spray flight. The airplane was then serviced with 40 gallons of Jet A fuel through a single point refueling port. The pilot checked the fuel level again and noted the right tank had approximately 1-1/2 inch more fuel than the left tank, or roughly 1/2 capacity in the left tank and between 1/2 and 2/3 capacity in the right tank.

The pilot took off with 375 gallons of chemical mix to spray two corn circular fields. He used a left hand reverse racetrack pattern to spray the two circles. Halfway through the application he checked the fuel gauges and noted both were reading between 1/4 and 1/2 tank. On his final swath of the field, the pilot climbed over a set of power lines. It was his intention to utilize the southerly wind to drift the spray under the power lines to the edge of the field. He performed a right side slip maneuver (right wing down, left rudder) to spray the west circle, leveled his wings, and repeated the maneuver to spray the east circle. He then initiated a 60-degree bank right climbing turn from a height of about 30 feet. The pilot said that during the climbing turn, "altitude and decrease in airspeed felt normal." He looked out the right side of the airplane to check the spray pattern. When he attempted to level the wings at an altitude between 100 and 150 feet, the right wing "continued to drop followed by the nose." He said the stall warning horn never sounded, and there was no aerodynamic buffet. He opened the throttle completely, but the engine did not respond. The airplane struck a pivotal sprinkler and impacted terrain.

The pilot said the airplane was destroyed "from the nose to the front of the cockpit, including the prop[eller], engine, hopper, wings, main landing gear, windshield, and spray gear. The right wing impacted a center pivot sprinkler, damaging the end three sections. The crash area damaged approximately 5 acres of alfalfa."

Asked how the accident could have been prevented, the pilot answered that he should have realized the engine had lost power "when I still had enough airspeed. Everything in the right hand turn felt normal with aircraft altitude and decreasing airspeed." The pilot also said it was his opinion that the engine lost power "due to unporting of fuel from the tank to the engine [induced] by the slip maneuver." The pilot said that although there are no placards in the airplane prohibiting slips, there is a placard that warns a pilot of skidding turns which may cause fuel migration between tanks."

## Aircraft

- Registration: [N61318](https://openairdocs.org/deregistered/N61318-2010-11-18), registration cancelled 2010-11-18, S/N 402B-0980, built 1995 (OpenAirDocs)
- Reported make and model: Air Tractor AT-402B
- Registry model: [Air Tractor AT-402B](https://openairdocs.org/model/air-tractor-at-402b) (registry code 0390208) (OpenAirDocs)
- Registry engine: [Pratt & Whitney PT6A series](https://openairdocs.org/engine/pratt-whitney-pt6a-series) (registry code 52034, reciprocating) (OpenAirDocs)
- Category: Airplane
- Serial number: 402B-0980
- Airframe hours: 7674
- Engines: Pratt & Whitney PT6A-34AG 783 horsepower turbo prop
- Damage: Destroyed
- Flight: Aerial application, Part 137
- Registered owner: Tri-Rotor Spray & Chemical
- Airworthiness certificate: Special, Restricted (Special)
- Last inspection: Annual, July 1, 2008, 46 hours before
- Departed: 36K, Lakin, KS
- Destination: 36K, Lakin, KS

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 34; injuries: minor; commercial; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 2, with waivers/limitations; last flight review March 1, 2008; seat: center; flight hours: 2,867 total, 193 in this make and model, 2,492 as pilot in command, 240 in the last 90 days, 122 in the last 30 days

## Weather

- Conditions: Visual (VMC), Day
- Wind: 210° at 10 knots, gusting 16
- Visibility: 10 statute miles
- Lowest ceiling: none
- Temperature: 75 °F, dew point 55 °F
- Altimeter: 30.06 inHg
- Observed at: ULS

## 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 20080720841709A](https://openairdocs.org/incident/20080720841709A), Jul 20, 2008: Airtrc AT402B, Deerfield, KS, Substantial damage. (-23) On 07-20-08 at approx. 0800 hrs local the aircraft departed lakin airport (36K)on an agricultural spray mission. Prior to departure 375 gal of chemical…

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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