# NTSB CEN13LA168: Air Tractor AT-502, N198LA, Forrest City, AR, February 7, 2013 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Limited investigation · Final report - Date: February 7, 2013, 16:00 local (22:00 UTC) - Place: Forrest City, AR - Coordinates: 34.946388, -90.774444 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=34.9464&lon=-90.7744&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Defining event: [Maneuvering: Flight control sys malf/fail](https://openairdocs.org/ntsb-events/333) - Highest injury: Minor injuries - Injuries: 1 minor - Status: Completed, report January 30, 2014 - Report: Approved by Office Director - NTSB office: Central Region - Parties: FAA FSDO - NTSB case key (mKey): 86264 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN13LA168 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/86264/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=86264 - Page: https://openairdocs.org/ntsb/CEN13LA168 ## Probable cause The in-flight separation of the left aileron's push-pull rod and hardware. Contributing to the accident was the failure of maintenance personnel to apply proper torque to the self-locking nuts. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Flight control system: aileron control system](https://openairdocs.org/ntsb-findings/01022710): Aircraft › Aircraft systems · Incorrect service/maintenance (probable cause); cases with it: [Air Tractor AT-502, 1 case](https://openairdocs.org/ntsb-findings/01022710/cases.md?model=0390303), [All aircraft, 45 cases](https://openairdocs.org/ntsb-findings/01022710/cases.md) - [Maintenance: installation](https://openairdocs.org/ntsb-findings/02062035): Personnel issues › Task performance · Maintenance personnel (probable cause); cases with it: [Air Tractor AT-502, 3 cases](https://openairdocs.org/ntsb-findings/02062035/cases.md?model=0390303), [All aircraft, 371 cases](https://openairdocs.org/ntsb-findings/02062035/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Maneuvering: Flight control sys malf/fail](https://openairdocs.org/ntsb-events/333) (defining event); cases with it: [Air Tractor AT-502, 1 case](https://openairdocs.org/ntsb-events/333/sequence.md?model=0390303), [All aircraft, 410 cases](https://openairdocs.org/ntsb-events/333/sequence.md) - [Landing: Off-field or emergency landing](https://openairdocs.org/ntsb-events/440); cases with it: [Air Tractor AT-502, 7 cases](https://openairdocs.org/ntsb-events/440/sequence.md?model=0390303), [All aircraft, 3,365 cases](https://openairdocs.org/ntsb-events/440/sequence.md) ## Analysis After making an agricultural application, the pilot made a climbing left turn; the airplane then began vibrating and shaking. The pilot was able to return the airplane to level flight, but it rocked left and right, with the left aileron going up and down from stop to stop. The pilot chose to perform an emergency landing in a field next to an airport. A postaccident examination of the airplane revealed that the two aileron push-pull rod bolts were missing. The bolts and associated hardware were not located among the wreckage. The airplane had undergone extensive maintenance about 5 months before the accident. A review of the airplane's maintenance manual revealed that the nuts installed in the airplane control system are self-locking nuts, which can loosen if insufficient torque is applied to them. It is likely that maintenance personnel applied improper torque to the aileron's push-pull rod self-locking nuts, which resulted in the eventual loosening of the nuts and the separation of the left aileron's push-pull rod and hardware. ## Factual narrative On February 7, 2013, about 1600 central standard time, an Air Tractor AT-502 airplane, N198LA, collided with terrain during a landing near Forrest City, Arkansas. The commercial rated pilot was injured and the airplane was substantially damaged. The airplane was registered to and operated by South Delta Aviation, LLC, West Helena, Arkansas, under the provisions of 14 Code of Federal Regulations Part 91 as a maintenance test flight. Visual meteorological conditions prevailed for the flight that operated without a flight plan. The pilot reported that he departed with 150 gallons of water to calibrate the spray system on the airplane. After making a spray pass, he started a climbing turn to the left; the airplane then began vibrating and shaking. The pilot added that he managed to get the airplane straight and level, but still rocked left and right. He further added that the left aileron was going up and down; stop to stop. The pilot found that as he slowed the airplane to 90 mph, he would lose aileron control and the airplane would start a slow left turn while rocking back and forth. The pilot then performed a long circle and selected a hay field, next to the airport for the emergency off-field landing. According to the responding Federal Aviation Administration (FAA) inspector, the airplane was substantially damaged during the accident. Additionally, inspection of the airplane revealed that the two bolts in the aileron push-pull rod were missing. The bolts and associated hardware were not located among the wreckage. The inspector also noted that the airplane had undergone extensive maintenance, about five months before the accident. A review of the airplane's maintenance manual revealed that the nuts installed in the airplane control system are self-locking nuts. ## Aircraft - Registration: [N198LA](https://openairdocs.org/aircraft/N198LA), registered now, S/N 502-0198, built 1993 (OpenAirDocs) - Reported make and model: AIR TRACTOR INC AT-502 - Registry model: [Air Tractor AT-502](https://openairdocs.org/model/air-tractor-at-502) (registry code 0390303) (OpenAirDocs) - Registry engine: [Pratt & Whitney PT6A series](https://openairdocs.org/engine/pratt-whitney-pt6a-series) (registry code 52032, turbo-prop) (OpenAirDocs) - Category: Airplane - Serial number: 502-0198 - Engines: P&W PT6A SER 750 horsepower turbo prop - Damage: Substantial damage - Flight: Other work use, Part 91 - Operator: South Delta Aviation Inc - Registered owner: South Delta Aviation Inc - Airworthiness certificate: Special, Restricted (Special) - Last inspection: Annual, September 1, 2013 - Departed: Forrest CIty, AR - Destination: Forrest CIty, AR ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 62; injuries: minor; commercial; airplane ratings: single-engine land; medical: class 2, without waivers/limitations; seat: single; flight hours: 22,300 total, 22,300 as pilot in command, 15 in the last 90 days ## Weather - Conditions: Visual (VMC), Day - Wind: 230° at 3 knots - Visibility: 10 statute miles - Lowest ceiling: 4,200 ft broken - Temperature: 64 °F, dew point 54 °F - Altimeter: 29.92 inHg - Observed at: KAWM ## 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 20130207002059A](https://openairdocs.org/incident/20130207002059A), Feb 7, 2013: Air Tractor Inc AT-502, Forrest City, AR, Substantial damage. The pilot stated after making the first pass, spraying water to test the GPS, he started a left turn. At the top of the turn at about 45 degrees bank suddenly… ## Other investigations on N198LA (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 CEN09CA323](https://openairdocs.org/ntsb/CEN09CA323), May 29, 2009: Air Tractor AT-502 (N198LA), Mendota, IL, substantial damage. Probable cause: The pilot's inadequate preflight planning and preparation and his failure to perform an aborted takeoff. ## Docket (4 files) The files NTSB released with the investigation on November 26, 2013, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=86264. 1.6 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 1.0 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40405062&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - Weather Reports and Records (item 2, .PDF, 129 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40405065&FileExtension=.PDF&FileName=Weather%20Reports%20and%20Records-Master.PDF - Extract from Parts Manual (item 3, .PDF, 432 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40405106&FileExtension=.PDF&FileName=Extract%20from%20Parts%20Manual-Master.PDF - Other Pertinent Forms and Reports (Memo for Record) (item 4, .PDF, 41 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40405095&FileExtension=.PDF&FileName=Other%20Pertinent%20Forms%20and%20Reports%20(Memo%20for%20Record)-Master.PDF 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.