# NTSB CEN11LA544: Air Tractor AT802, N396LA, Ullin, IL, July 22, 2011 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Limited investigation · Final report - Date: July 22, 2011, 14:00 local (19:00 UTC) - Place: Ullin, IL - Coordinates: 37.321945, -89.131942 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=37.3219&lon=-89.1319&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Defining event: [Enroute: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342) - Highest injury: Minor injuries - Injuries: 1 minor - Status: Completed, report January 15, 2013 - Report: Approved by Office Director - NTSB office: Central Region - Parties: Pratt & Whitney Canada Corp., Woodward Governor Company, Transporation Safety Board of Canada, Federal Aviation Administration - NTSB case key (mKey): 81389 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN11LA544 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/81389/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=81389 - Page: https://openairdocs.org/ntsb/CEN11LA544 ## Probable cause The loss of engine power for reasons that could not be determined because postaccident examination of the engine did not reveal any anomalies that would have precluded normal operation. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Not determined](https://openairdocs.org/ntsb-findings/05000000): Not determined › Not determined · Unknown/Not determined (probable cause); cases with it: [Air Tractor AT-802A, 7 cases](https://openairdocs.org/ntsb-findings/05000000/cases.md?model=0390308), [All aircraft, 2,247 cases](https://openairdocs.org/ntsb-findings/05000000/cases.md) - [Aircraft capability: climb capability](https://openairdocs.org/ntsb-findings/01061010): Aircraft › Aircraft oper/perf/capability · Attain/maintain not possible; cases with it: [Air Tractor AT-802A, 2 cases](https://openairdocs.org/ntsb-findings/01061010/cases.md?model=0390308), [All aircraft, 183 cases](https://openairdocs.org/ntsb-findings/01061010/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Enroute: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342) (defining event); cases with it: [Air Tractor AT-802A, 1 case](https://openairdocs.org/ntsb-events/342/sequence.md?model=0390308), [All aircraft, 1,858 cases](https://openairdocs.org/ntsb-events/342/sequence.md) - [Emergency descent: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342); cases with it: [Air Tractor AT-802A, 1 case](https://openairdocs.org/ntsb-events/342/sequence.md?model=0390308), [All aircraft, 1,858 cases](https://openairdocs.org/ntsb-events/342/sequence.md) - [Landing: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Air Tractor AT-802A, 27 cases](https://openairdocs.org/ntsb-events/470/sequence.md?model=0390308), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) ## Analysis The pilot reported that the airplane’s engine surged and lost power during cruise flight. The pilot stated that he was unable to attain a climb rate and that the emergency procedures he used did not affect the surging or loss of engine power. The pilot landed the airplane on a field immersed in water. An examination of the engine and overspeed governor did not identify any anomalies that would account for surging or a loss of engine power. The internal corrosion found on examination of the overspeed governor was most likely due to its water immersion after the accident. ## Factual narrative On July 22, 2011, about 1400 central daylight time, an Air Tractor Inc, AT802/A, N396LA, experienced engine surging and a loss of engine power following the completion of an aerial application of a field near Ullin, Illinois. The pilot subsequently made a forced landing to a field. The certificated commercial pilot sustained minor injuries. The airplane sustained substantial damage. The airplane was registered to and operated by Thompson Flying Service LLC under the provisions of 14 Code of Federal Regulations Part 137 as an aerial application flight. Visual meteorological conditions prevailed at the time of the accident. The flight originated from Flora Municipal Airport, Flora, Illinois. The pilot stated that while returning from an aerial application near Flora, Illinois, the engine started to surge and “slip.” He said it felt like a “clutch was going out in a truck.” The engine power would fade away and come back. He did not hear any “popping” or “unusual” noises. The torque and propeller speed gauge indications did not fluctuate. The engine gauges displayed: torque pressure – 30 psi, propeller speed – 1,400 to 1,500 rpm, gas generator speed - 95 percent, and inter-turbine temperature – 740 to 750 degrees Celsius. The airspeed was about 150 mph during “normal” cruise. The oil temperature was hotter than normal, but it was below the upper limit of the oil temperature range. The first loss of engine power occurred about 1,500 feet above ground level at a terrain elevation about 340 feet mean sea level. The pilot tried to climb the airplane three times, but each successive climb resulted in altitude loss. He said that he performed emergency procedures by selecting the auxiliary fuel [pump] on and selecting the igniters to continuous operation. He said that the emergency procedures had no effect on engine power or the surging. The pilot said that the propeller had been rotating and that it was feathered before landing on a field covered with about 4 inches of water. The airplane was powered by a Pratt & Whitney PT6A-65AG, serial number 32254. The last maintenance logbook entry dated July 13, 2011, indicated that the engine accumulated: time since new - 5,020.8 hours; cycles since new - 5,020, time since overhaul - 2,527.7 hours; cycles since overhaul - 2,527. The last maintenance logbook entry also showed that the gas generator was partially disassembled for a suspected bearing failure and overhauled number 1 and 2 bearings were installed. Overhauled accessory gear box bearings were installed. The accessory gears, fuel pump, pressure pump gear, and associated hardware were demagnetized. The gas generator section was reassembled and one serviceable thermocouple was installed. The engine was removed from the airplane and shipped to Pratt & Whitney Canada for disassembly examination under the supervision of the Transportation Safety Board of Canada. The examination did not reveal any anomalies associated with the reported power surge. Theexamination also revealed that a fracture of the reduction gearbox front case at the A-flange and a fracture of the second stage carrier housing at the web were characteristic of engine power at the time of impact. The Woodward overspeed governor, part number 210960 B, serial number 16517050, underwent testing and disassembly at Woodward Governor Company under the supervision of the National Transportation Safety Board. Visual inspection of the governor revealed the presence non-Woodward safety wire and torque seal on the governor. The governor exhibited external contamination consistent with sand and/or dirt. Discoloration consistent with corrosion/rust was present on the drive gear. Testing showed that the minimum and maximum speeds were set about 0.5 percent high at both points. Disassembly showed that the governor interior exhibited corrosion/rust. The reset piston was sticking, which was attributed to internal corrosion/rust. ## Aircraft - Registration: [N396LA](https://openairdocs.org/aircraft/N396LA), registered now, S/N 802A-0331 (OpenAirDocs) - Reported make and model: AIR TRACTOR AT802 (A) - Registry model: [Air Tractor AT-802A](https://openairdocs.org/model/air-tractor-at-802a) (registry code 0390308) (OpenAirDocs) - Registry engine: [Pratt & Whitney Canada PT6A-65AG](https://openairdocs.org/engine/pratt-whitney-canada-pt6a-65ag) (registry code 52109, turbo-prop) (OpenAirDocs) - Category: Airplane - Serial number: 802A-0331 - Airframe hours: 1049 - Engines: Pratt & Whitney of Canada PT6A-65AG 1300 horsepower turbo prop - Damage: Substantial damage - Flight: Aerial application, Part 137 - Operator: Thompson Flying Service LLC - Registered owner: Thompson Flying Service LLC - Airworthiness certificate: Special, Restricted (Special) - Last inspection: Annual, June 23, 2011 - Departed: FOA, Flora, IL - Destination: Ullin, IL ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 37; injuries: minor; commercial; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 2, without waivers/limitations; last flight review December 13, 2010; seat: center; flight hours: 3,371 total, 1,198 in this make and model, 3,371 as pilot in command ## Weather - Conditions: Visual (VMC), Day - Wind: 170° at 7 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 95 °F, dew point 73 °F - Altimeter: 29.94 inHg - Observed at: FOA, 24 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 20110722017199A](https://openairdocs.org/incident/20110722017199A), Jul 22, 2011: Air Tractor Inc AT-802A, Ullin, IL, Substantial damage. The aircraft lost engine power at approximately 1500 feet MSL. The pilot turned on auxillary fuel and the igniters. The procedures had no effect, so the pilot… ## Docket (7 files) The files NTSB released with the investigation on November 14, 2012, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=81389. 1.1 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 549 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40379602&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - Record of Conversation - Pilot (item 2, .PDF, 51 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40379603&FileExtension=.PDF&FileName=Record%20of%20Conversation%20-%20Pilot-Master.PDF - Pratt & Whitney Statement of Examination (item 3, .PDF, 55 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40380460&FileExtension=.PDF&FileName=Pratt%20%26%20Whitney%20Statement%20of%20Examination-Master.PDF - Record of Examination - Engine (item 4, .PDF, 50 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40379618&FileExtension=.PDF&FileName=Record%20of%20Examination%20-%20Engine-Master.PDF - Record of Examination - Governor (item 5, .PDF, 50 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40379619&FileExtension=.PDF&FileName=Record%20of%20Examination%20-%20Governor-Master.PDF - Maintenance Records - Logbook Excerpt (item 6, .PDF, 258 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40379605&FileExtension=.PDF&FileName=Maintenance%20Records%20-%20Logbook%20Excerpt-Redacted.PDF - Statement of Party Representatives to NTSB Investigation (item 7, .PDF, 89 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40379606&FileExtension=.PDF&FileName=Statement%20of%20Party%20Representatives%20to%20NTSB%20Investigation-Redacted.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.