# NTSB CEN09LA503: Air Tractor AT401, N60747, Waterloo, IA, August 4, 2009 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: August 4, 2009, 12:45 local (17:45 UTC) - Place: Waterloo, IA - Coordinates: 42.556945, -92.400276 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=42.5569&lon=-92.4003&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Defining event: [Maneuvering: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report May 28, 2010 - Report: Approved by Office Director - NTSB office: Central Region - Parties: Federal Aviation Administration - NTSB case key (mKey): 74469 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN09LA503 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/74469/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=74469 - Page: https://openairdocs.org/ntsb/CEN09LA503 ## Probable cause A loss of engine power for undetermined reasons. ## 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-401B, 1 case](https://openairdocs.org/ntsb-findings/05000000/cases.md?model=0390207), [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. - [Maneuvering: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341) (defining event); cases with it: [Air Tractor AT-401B, 1 case](https://openairdocs.org/ntsb-events/341/sequence.md?model=0390207), [All aircraft, 3,820 cases](https://openairdocs.org/ntsb-events/341/sequence.md) - [Emergency descent: Off-field or emergency landing](https://openairdocs.org/ntsb-events/440); cases with it: [Air Tractor AT-401B, 1 case](https://openairdocs.org/ntsb-events/440/sequence.md?model=0390207), [All aircraft, 3,365 cases](https://openairdocs.org/ntsb-events/440/sequence.md) ## Analysis The pilot had completed his first spray pass of the flight and was maneuvering for another pass when the airplane experienced a loss of engine power. The pilot attempted a restart; however, it was unsuccessful. He elected to perform a forced landing to a corn field. During the forced landing, the airplane sustained substantial damage to the wings and empennage. Examination of the airframe, disassembly of the engine, and functional testing of the engine components showed no anomalies that precluded normal operation. The reason for the loss of engine power was not determined. ## Factual narrative On August 4, 2009, approximately 1245 central daylight time, an Air Tractor AT-401B agricultural airplane, N60747, sustained substantial damage when it impacted terrain during a forced landing to a field near Waterloo, Iowa. The commercial pilot, who was the sole occupant, was not injured. The airplane was registered to and operated by Dakota Executive Flight, Inc., Miller, South Dakota. Visual meteorological conditions prevailed, and a flight plan was not filed for the Title 14 Code of Federal Regulations Part 137 aerial application flight. The flight departed Oelwein, Iowa, approximately 1215. According to the pilot's statement, he had just completed his first spray pass of the flight and was maneuvering for another pass when the airplane experienced an engine problem. He reported, "I was heading east while looking south at the auto traffic when I felt deceleration of the aircraft. During my instrument scan I noted that I had primary fuel pressure and the torque had decayed [from] approximately 70 percent to about 45 percent and was decaying rapidly. There was a [slight] hesitation in the decay at 40 percent then it decayed further. At this time, I executed my restart procedure, but was unable to get a relight." He elected to perform a forced landing to a corn field. The airplane impacted corn (approximately 9 feet tall) and terrain. The airplane contained approximately 140 gallons of fuel at the time of the accident. The pilot reported to local authorities that to his knowledge, the airplane had experienced a loss of engine power on four previous flights on unknown dates. Examination of the airplane revealed the wings were bent, the empennage was bent, and the main landing gear was folded underneath the fuselage. The airplane was recovered for further examination. A review of the maintenance records showed on March 16, 2009, the GE/Walter M601E-11 engine underwent a 300-hour inspection in accordance with the maintenance manual. At the time of the inspection, the engine had accumulated 810 total hours engine service time. The engine had accumulated 940 total hours engine service time at the time of the accident. On August 10, 2009, a Federal Aviation Administration inspector examined the airplane. According to the inspector, fuel was found at the fuel pump inlet, the oil filter was clear of contaminants, and the propeller rotated "smoothly" by hand. The compressor inlet showed no damage or foreign object debris. No anomalies with the engine were noted. The engine was removed and shipped to the factory in the Czech Republic for further examination. On November 18-19, 2009, at the GE Aircraft Engine (GEAC) facility in Prague, Czech Republic, the engine was examined under the supervision of the Czech Civil Aviation Authority. Examination of the engine showed no visible damage to the external cases, reduction gearbox, gas generator case, accessory gear box, and the fuel accessory components. All pneumatic lines were found secured. The engine wasdisassembled and no internal damage was noted in the compressor, combustion, and turbine sections, and gear boxes. According to the manufacturer, no failures or damage which could adversely affect the engine operation were found, and no evidence of a pre-impact mechanical anomaly was found. On November 20, 2009, the fuel distributor was bench tested and no anomalies were noted during the test. On November 26, 2009, the torque indicator was functionally tested and no anomalies were noted during the test. On November 30, 2009, the fuel control unit and fuel pump were tested on a slave Walter engine. No anomalies were noted during the test. The fuel control unit was sent to the manufacturer for further testing. All of the test results were acceptable except acceleration, which was found shorter than required in the technical specification. According to the engine manufacturer, "This anomaly should not have adverse effect on the situation related with this investigated case. In addition, this anomaly did not manifest during engine functional test at GEAC and engine parameters were found acceptable." ## Aircraft - Registration: [N60747](https://openairdocs.org/deregistered/N60747-2011-11-16), registration cancelled 2011-11-16, S/N 401B-1000, built 1996 (OpenAirDocs) - Reported make and model: AIR TRACTOR AT401 (B) - Registry model: [Air Tractor AT-401B](https://openairdocs.org/model/air-tractor-at-401b) (registry code 0390207) (OpenAirDocs) - Registry engine: [Pratt & Whitney R1340 series](https://openairdocs.org/engine/pratt-whitney-r1340-series) (registry code 52016, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 401B-1000 - Airframe hours: 2381 - Engines: Walter M601E-11 750 horsepower turbo prop - Damage: Substantial damage - Flight: Aerial application, Part 137 - Operator: Dakota Executive Flight, Inc - Registered owner: Dakota Executive Flight, Inc - Airworthiness certificate: Standard, Utility - Last inspection: Annual, April 15, 2009 - Departed: OLZ, Oelwein, IA - Destination: OLZ, Oelwein, IA ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 62; injuries: none; commercial, airline transport; airplane ratings: multi-engine land, single-engine sea, single-engine land; instrument ratings: airplane; medical: class 2, with waivers/limitations; last flight review April 10, 2009; seat: center; flight hours: 25,675 total, 153 in this make and model, 25,322 as pilot in command, 89 in the last 90 days, 37 in the last 30 days, 5 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 360° at 10 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 81 °F - Altimeter: 29.89 inHg ## 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 20090804016509A](https://openairdocs.org/incident/20090804016509A), Aug 4, 2009: Airtrc AT401B, Oelwein, IA, Substantial damage. (-23) Two separate witnesses stated that the aircraft let out a puff of smoke prior to the accident. The aircraft lost engine power. The pilot made an… ## Other investigations on N60747 (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 CHI02LA206](https://openairdocs.org/ntsb/CHI02LA206), Jul 22, 2002: Air Tractor AT-401B (N60747), Pratt, KS, substantial damage. Probable cause: The pilot's failure to maintain terrain clearance. A factor was low altitude flight. ## Docket (8 files) The files NTSB released with the investigation on March 4, 2010, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=74469. 6.2 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 350 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40326419&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - Reports from Local Agencies - Sheriff's Report (item 2, .PDF, 240 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40326420&FileExtension=.PDF&FileName=Reports%20from%20Local%20Agencies%20-%20Sheriff%27s%20Report-Redacted.PDF - Engine Maintenance Records (item 3, .PDF, 2.0 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40326421&FileExtension=.PDF&FileName=Engine%20Maintenance%20Records-Redacted.PDF - Engine Manufacturer Report (item 4, .PDF, 1.7 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40326422&FileExtension=.PDF&FileName=Engine%20Manufacturer%20Report-Redacted.PDF - Engine Manufacturer Report Attachment (item 5, .PDF, 58 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40326423&FileExtension=.PDF&FileName=Engine%20Manufacturer%20Report%20Attachment-Redacted.PDF - Engine Component Test Reports (item 6, .PDF, 1.3 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40326424&FileExtension=.PDF&FileName=Engine%20Component%20Test%20Reports-Redacted.PDF - Email Correspondence regarding FCU (item 7, .PDF, 28 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40326425&FileExtension=.PDF&FileName=Email%20Correspondence%20regarding%20FCU-Redacted.PDF - Statement of Party Representatives to NTSB Investigation (item 8, .PDF, 432 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40326426&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.