# NTSB FTW04LA130: Air Tractor AT-401, N4508Y, San Angelo, TX, May 19, 2004 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: May 19, 2004, 06:45 local (11:45 UTC) - Place: San Angelo, TX - Coordinates: 31.375, -100.455276 - Nearby events: https://openairdocs.org/map.md?lat=31.3750&lon=-100.4553&mi=10 - Phase of flight: [Takeoff](https://openairdocs.org/ntsb-phases/300) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report January 24, 2005 - Report: Approved by Office Director - Parties: Federal Aviation Administration - NTSB case key (mKey): 59240 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=FTW04LA130 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/59240/pdf - Page: https://openairdocs.org/ntsb/FTW04LA130 ## Probable cause The loss of engine power for undetermined reasons. A contributing factor was the soft terrain encountered during the aborted takeoff. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of engine power, takeoff - aborted - reason for occurrence undetermined (cause) - On ground/water encounter with terrain/water, takeoff - terrain condition - soft (contributing factor) ## Analysis During takeoff for an aerial application flight, the engine gradually lost power. The pilot aborted the takeoff, and the airplane veered into a soft wheat field. Examination of the airplane revealed fuel was observed at the fuel pump, the throttle and mixture linkages were intact, and engine continuity was established by rotating the propeller through by hand. Examination of the carburetor revealed the top housing flange was bent which resulted in an air leak. The cotter key was missing from the economizer stud and the stud was adjusted too a full rich setting at some time between the overhaul and the accident. The fuel inlet screen, float bowl, and inlet needle were free and clear of contaminants. The reason for the loss of engine power was not determined. ## Factual narrative On May 19, 2004, approximately 0645 central daylight time, an Air Tractor AT-401 single-engine agricultural airplane, N4508Y, sustained substantial damage when it impacted terrain following a loss of engine power during takeoff from a private airstrip near San Angelo, Texas. The commercial pilot, who was the sole occupant and registered owner of the airplane, was not injured. Visual metrological conditions prevailed, and a flight plan was not filed for the 14 Code of Federal Regulations Part 137 aerial application flight. The local flight was originating at the time of the accident. According to an FAA inspector, the pilot reported that during takeoff of the first flight of the day, the engine gradually lost power. The pilot aborted the takeoff, and the airplane veered into a soft wheat field. Examination of the airplane revealed the main landing gear was damaged, and the left wing was partially separated. Fuel was observed at the fuel pump, the throttle and mixture linkages were intact, and engine continuity was established by rotating the propeller through by hand. According to the pilot, the carburetor "recently" had been overhauled. The carburetor was removed and shipped to the overhaul repair station for further examination. On June 16, 2004, under the supervision of an FAA inspector, the Bendix NAY9E1 carburetor, serial number 5638771, was examined and disassembled at the overhaul repair station. Examination of the carburetor revealed the top housing flange was bent which resulted in an air leak. The cotter key was missing from the economizer stud and the stud was adjusted to a full rich setting at some time between the overhaul and the accident. The fuel inlet screen, float bowl, and inlet needle were free and clear of contaminants. The reason for the loss of engine power was not determined. ## Aircraft - Registration: [N4508Y](https://openairdocs.org/deregistered/N4508Y-2022-11-23), registration cancelled 2022-11-23, S/N 401-0751, built 1990 (OpenAirDocs) - Reported make and model: Air Tractor AT-401 - Registry model: [Air Tractor AT-401](https://openairdocs.org/model/air-tractor-at-401) (registry code 0390204) (OpenAirDocs) - Registry engine: [Pratt & Whitney PT6A series](https://openairdocs.org/engine/pratt-whitney-pt6a-series) (registry code 52034, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 401-0751 - Airframe hours: 5880 - Engines: Pratt & Whitney R-1340 600 horsepower reciprocating - Damage: Destroyed - Flight: Part 137 - Registered owner: Rodney N. Hoelscher - Airworthiness certificate: Special, Restricted (Special) - Last inspection: 100 hour, April 15, 2004, 34 hours before - Departed: San Angelo, TX - Airport: runway 18, 2,880 × 30 ft, gravel ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 41; injuries: none; commercial; airplane ratings: single-engine land; medical: class 2, valid medical--w/ waivers/lim; last flight review January 2, 2003; seat: center; flight hours: 7,609 total, 1,784 in this make and model, 60 in the last 90 days, 20 in the last 30 days, 0 in the last 24 hours ## Weather - Conditions: Visual (VMC), Dawn - Wind: 190° at 5 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 70 °F ## 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 20040519016339A](https://openairdocs.org/incident/20040519016339A), May 19, 2004: Airtrc AT401, San Angelo, TX, Substantial damage. (-23) On may 19, 2004, approximately 0700 CDT, an air tractor AT-401 N4508Y sustained substantial damage when it crashed following a loss of power during… ## Other investigations on N4508Y (1) 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 LAX00LA271](https://openairdocs.org/ntsb/LAX00LA271), Jul 13, 2000: Air Tractor AT-401 (N4508Y), Ripley, CA, substantial damage. Probable cause: A loss of engine power due to the separation of a connecting rod from the crankshaft. 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.