# NTSB CHI04CA162: Air Tractor AT-401, N1013N, Britton, SD, June 23, 2004 - Type: NTSB accident investigation - Classification: Accident · No injuries · Data collection · Final report - Date: June 23, 2004, 09:45 local (14:45 UTC) - Place: Britton, SD - Coordinates: 45.789443, -97.749443 - Nearby events: https://openairdocs.org/map.md?lat=45.7894&lon=-97.7494&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report September 1, 2004 - Report: Approved by Office Director - Parties: Federal Aviation Administration - Rapid City FSDO - NTSB case key (mKey): 59539 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CHI04CA162 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/59539/pdf - Page: https://openairdocs.org/ntsb/CHI04CA162 ## Probable cause The loss of engine power due to a stuck exhaust valve and the unsuitable terrain encountered during the forced landing. A factor to the accident was the soft terrain condition. ## 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,valve,exhaust - seized (cause) - Forced landing, emergency descent/landing - On ground/water encounter with terrain/water, emergency landing - terrain condition - soft (contributing factor) - Nose over, emergency landing ## Analysis The aerial-application airplane impacted soft terrain and nosed over during a forced landing following a loss of engine power. The pilot reported the engine began running rough after he completed his spraying and was returning to the departure airport. The pilot stated he eventually had to perform a forced landing into a soft field, during which the airplane nosed over. The engine was inspected and the shaft mount for the number eight cylinder rocker-arm was cracked and separated, consistent with damage caused by a stuck exhaust valve. ## Factual narrative On June 23, 2004, at 0945 central daylight time, an Air Tractor AT-401, N1013N, piloted by a commercial pilot, sustained substantial damage during a forced landing near Britton, South Dakota. Visual meteorological conditions prevailed at the time of the accident. The aerial application flight was operating under the provisions of 14 CFR Part 137 without a flight plan. The pilot was not injured. The local flight departed Britton Municipal Airport (BTN), Britton, South Dakota, at 0900. The pilot reported that the engine began running rough after he completed spraying and was returning to BTN. The pilot stated he verified the operation of both magnetos, but the engine continued to run rough. The pilot reported vehicular traffic prevented a landing on a nearby road, so he attempted to fly the airplane back to BTN. The pilot stated he eventually had to perform a forced landing into a soft field, during which the airplane nosed over. A Federal Aviation Administration (FAA) inspector examined the engine and found the shaft mount for the number eight cylinder exhaust rocker-arm cracked and separated, consistent with damage caused by a stuck exhaust valve. ## Aircraft - Registration: [N1013N](https://openairdocs.org/aircraft/N1013N), registered now, S/N 401-0722 (OpenAirDocs) - Reported make and model: Air Tractor AT-401 - Registry model: [Air Tractor AT-402A](https://openairdocs.org/model/air-tractor-at-402a) (registry code 0390206) (OpenAirDocs) - Registry engine: [Pratt & Whitney PT6A-20A series](https://openairdocs.org/engine/pratt-whitney-pt6a-20a-series) (registry code 52139, turbo-prop) (OpenAirDocs) - Category: Airplane - Serial number: 401-0722 - Airframe hours: 2967.9 - Engines: Pratt & Whitney 1340 600 horsepower reciprocating - Damage: Substantial damage - Flight: Aerial application, Part 137 - Registered owner: Dakota Ag Service, Inc. - Airworthiness certificate: Special, Restricted (Special) - Last inspection: Annual, April 28, 2004, 94.4 hours before - Departed: BTN, Britton, SD - Destination: BTN, Britton, SD ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 61; injuries: none; commercial; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 2, valid medical--w/ waivers/lim; seat: center; flight hours: 11,000 total, 1,200 in this make and model, 8 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 320° at 20 knots, gusting 28 - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 73 °F, dew point 48 °F - Altimeter: 29.89 inHg - Observed at: ABR, 36 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 20040623012119A](https://openairdocs.org/incident/20040623012119A), Jun 23, 2004: Airtrc AT401, Britton, SD, Substantial damage. (-23) Pilot terry d. haven was spraying crops approximately seven miles NE of the Britton, SD airport (btn). He finished his last spray run and was heading… 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.