# NTSB CEN11LA598: Air Tractor AT-301, N73071, Edgeley, ND, August 13, 2011 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: August 13, 2011, 13:30 local (18:30 UTC) - Place: Edgeley, ND - Coordinates: 46.348609, -98.734725 - Nearby events: https://openairdocs.org/map.md?lat=46.3486&lon=-98.7347&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: No injuries - Injuries: 1 uninjured - Status: Completed, report August 29, 2013 - Report: Approved by Office Director - NTSB office: Central Region - Parties: FAA-Fargo FSDO - SAIBs cited in the narratives: [SAIB CE-09-35](https://openairdocs.org/saib/CE-09-35) (OpenAirDocs) - NTSB case key (mKey): 81605 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN11LA598 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/81605/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=81605 - Page: https://openairdocs.org/ntsb/CEN11LA598 ## Probable cause The loss of engine power for reasons that could not be determined because postaccident examination of the airplane and 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-301, 11 cases](https://openairdocs.org/ntsb-findings/05000000/cases.md?model=0390103), [All aircraft, 2,247 cases](https://openairdocs.org/ntsb-findings/05000000/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-301, 9 cases](https://openairdocs.org/ntsb-events/342/sequence.md?model=0390103), [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-301, 25 cases](https://openairdocs.org/ntsb-events/470/sequence.md?model=0390103), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) ## Analysis The pilot reported that shortly after leveling off and making a power reduction for cruise flight, he noticed that a descent had developed. The pilot added one notch of flaps and dumped the chemical load using the emergency dump handle but the descent continued. He landed the airplane in a bean field. A postaccident examination of the airplane and engine did not reveal any anomalies, nor were any anomalies noted in the airplane’s recent annual inspection. The temperature and dew point recorded at a nearby airport were in a range susceptible to the formation of carburetor ice at glide and cruise power settings. Carburetor icing usually results in engine roughness and a drop in manifold pressure. Since the pilot made no mention of engine roughness, a decrease in manifold pressure, and was able to increase manifold pressure during his attempts to arrest the descent, it is unlikely that the power loss was due to carburetor icing. The reason for the power loss could not be determined. ## Factual narrative On August 14, 2011, about 1230 central daylight time, an Air Tractor AT-301, N73071, sustained substantial damage to its fuselage during a forced landing to a bean field following a partial loss of engine power. The commercial pilot was not injured. The airplane was registered to and operated by Semper Fi Aviation under the provisions of 14 Code of Federal Regulations Part 137, as an aerial application flight. Visual meteorological conditions prevailed for the local flight, which was not operating on a flight plan. The flight originated from the Edgeley Municipal Airport (51D), Edgeley, North Dakota, about 1225. The pilot reported that he performed a normal takeoff in the agricultural airplane, climbed to about 200 feet above ground level, and established level flight. At that time, he reduced engine power to 30 inches of manifold air pressure (MAP) and 2,000 rpm. After several seconds of normal flight he noticed a descent developing and increased engine power to 32 inches MAP but received no response. The pilot added one notch of flaps and dumped the chemical load using the emergency dump handle but the descent continued. The pilot landed the airplane in a bean field. On-scene examination of the airplane after the accident by Federal Aviation Administration (FAA) inspectors did not reveal any preimpact mechanical failures. The engine was separated from the airplane and firewall damage had occurred. There were no outward signs of a mechanical failure of the engine. At the request of the local landowner, the pilot agreed to leave the airplane in the field until after the crops were harvested. There was no further examination of the airplane after removal from the field. The airplane was powered by a supercharged Pratt & Whitney R-1340-AN-1 engine bearing serial number 5684. The engine was rated to produce 600 horsepower for takeoff and 550 horsepower continuously. Maintenance records indicated that the airplane had received an annual inspection that was completed on April 6, 2011. The engine entry on that date noted the all cylinder compressions were 75/80 or better. Additionally, the oil filter was removed and cut open to examine the filter element. No anomalies were noted. The temperature and dew point recorded at the Oakes Municipal Airport, Oakes, North Dakota, about 29 nautical miles east of the accident, were 24 and 17 degrees Celsius. According to FAA Special Airworthiness Information Bulletin (SAIB) CE-09-35, these readings were in a range susceptible to the formation of carburetor ice at glide and cruise power settings. The SAIB further stated that carburetor icing can be detected by a drop in manifold pressure and that there is usually roughness in engine operation. The pilot made no mention of roughness in operation. ## Aircraft - Registration: [N73071](https://openairdocs.org/deregistered/N73071-2019-02-21), registration cancelled 2019-02-21, S/N 301-0617, built 1985 (OpenAirDocs) - Reported make and model: AIR TRACTOR INC AT-301 - Registry model: [Air Tractor AT-301](https://openairdocs.org/model/air-tractor-at-301) (registry code 0390103) (OpenAirDocs) - Registry engine: [Pratt & Whitney R1340 series](https://openairdocs.org/engine/pratt-whitney-r1340-series) (registry code 52016, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 301-0617 - Engines: P&W R1340 SERIES 600 horsepower reciprocating - Damage: Substantial damage - Flight: Aerial application, Part 137 - Operator: Semper Fi Aviation LLC - Registered owner: Semper Fi Aviation LLC - Airworthiness certificate: Special, Restricted (Special) - Last inspection: Annual, April 6, 2011 - Departed: 51D, Edgeley, ND - Destination: 51D, Edgeley, ND - Airport: 51D, Edgeley Municipal, runway 32, 3,600 × 60 ft ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 45; commercial; airplane ratings: single-engine land; medical: class 2, without waivers/limitations; last flight review August 11, 2010; seat: single; flight hours: 935 total ## Weather - Conditions: Visual (VMC), Day - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 75 °F, dew point 63 °F - Altimeter: 30.10 inHg - Observed at: 2D5, 29 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 20110813018559A](https://openairdocs.org/incident/20110813018559A), Aug 13, 2011: Air Tractor Inc AT-301, Edgeley, ND, Substantial damage. Aircraft departed runway and performed a normal take-off to the northwest, climbed to approximately 200 feet and established level flight. After several… ## Docket (4 files) The files NTSB released with the investigation on June 26, 2013, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=81605. 1.4 MB in all. - Pilot Statement (item 1, .PDF, 145 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40394991&FileExtension=.PDF&FileName=Pilot%20Statement-Redacted.PDF - Record of conversation with pilot (item 2, .PDF, 53 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40394992&FileExtension=.PDF&FileName=Record%20of%20conversation%20with%20pilot-Master.PDF - Aircraft Maintenance Recod excerpts (item 3, .PDF, 1.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40394993&FileExtension=.PDF&FileName=Aircraft%20Maintenance%20Recod%20excerpts-Redacted.PDF - FAA SAIB CE-09-05 (item 4, .PDF, 111 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40394995&FileExtension=.PDF&FileName=FAA%20SAIB%20CE-09-05-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.