# NTSB WPR14LA245: Air Tractor AT 502B, N502JS, Princeton, CA, June 13, 2014 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: June 13, 2014, 11:00 local (18:00 UTC) - Place: Princeton, CA - Coordinates: 39.393054, -122.035552 - Nearby events: https://openairdocs.org/map.md?lat=39.3931&lon=-122.0356&mi=10 - Phase of flight: [Takeoff](https://openairdocs.org/ntsb-phases/300) (OpenAirDocs' grouping) - Defining event: [Takeoff: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report March 26, 2015 - Report: Approved by Office Director - NTSB office: Western Pacific Region - Parties: Federal Aviation Administration, Pratt & Whitney - NTSB case key (mKey): 89442 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR14LA245 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/89442/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=89442 - Page: https://openairdocs.org/ntsb/WPR14LA245 ## Probable cause The partial loss of engine power during takeoff for reasons that could not be determined because postaccident examination 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-502B, 7 cases](https://openairdocs.org/ntsb-findings/05000000/cases.md?model=0390307), [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. - [Takeoff: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342) (defining event); cases with it: [Air Tractor AT-502B, 7 cases](https://openairdocs.org/ntsb-events/342/sequence.md?model=0390307), [All aircraft, 1,858 cases](https://openairdocs.org/ntsb-events/342/sequence.md) - [Takeoff: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Air Tractor AT-502B, 46 cases](https://openairdocs.org/ntsb-events/470/sequence.md?model=0390307), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) ## Analysis The pilot reported that, during takeoff from a dirt airstrip, the airplane lifted off normally but that, when it reached an altitude of about 10 to 15 ft above the ground, it felt like the engine was experiencing a partial loss of power. The airplane then settled toward the ground. The pilot added full power, but it still felt like the engine was only producing partial power. Subsequently, the airplane impacted the ground and came to rest upright. Postaccident examination of the airframe and engine revealed no evidence of preexisting mechanical malfunctions or failures that would have precluded normal operation. The engine was test run at various power settings with no anomalies noted. ## Factual narrative On June 13, 2014, about 1100 Pacific daylight time, an Air Tractor AT-502B, N502JS, was substantially damaged during takeoff from a dirt airstrip near Princeton, California, following a reported partial loss of engine power. The airplane was registered to a private individual, and operated by Michaud Aviation, Willows, California, under the provisions of Title 14 Code of Federal Regulations Part 137. The commercial pilot, sole occupant of the airplane, was not injured. Visual meteorological conditions prevailed, and no flight plan was filed for the local aerial application flight, which was originating at the time of the accident.In a written statement to the National Transportation Safety Board (NTSB) investigator-in-charge (IIC), the pilot reported that the airplane was loaded with about 3,000 pounds of fertilizer in the hopper and had about 115 gallons of Jet A fuel on board prior to departure. During takeoff to the north from a dirt airstrip, the airplane lifted off about two-thirds down the runway. The pilot stated that as the airplane reached an altitude of about 10 to 15 feet above the ground, it felt like it [the engine] was experiencing a partial loss of power, and settled towards the ground. The pilot added full power, and it still felt as if the engine was only producing partial power. Subsequently, the airplane impacted the ground and came to rest upright. Post-accident examination of the airplane by local law enforcement revealed that the fuselage was displaced to the right forward of the vertical stabilizer, and the right aileron was partially separated. The airplane was recovered to a secure location for further examination. The recovered airframe and engine were examined by the NTSB IIC on July 31, 2014, at the facilities of Air Transport, Phoenix, Arizona. The engine remained attached via all mounts to the airframe. All fuel, oil, and pneumatic lines remained attached and secure to their respective fittings. Continuity was established from all engine cockpit controls forward to the engine. The engine was removed and shipped to the manufacturer's facility for further examination. The airframe was mostly intact. The fuel selector valve was found in the "OFF" position. The fuel selector valve was placed in the "on" position, and compressed air was applied to the right side fuel inlet port while the left fuel inlet port was blocked using a metal cap. Fuel was observed expelling from the engine supply fuel line. The fuel filter drain plug was removed, and a fuel sample was obtained. The fuel was found to be free of debris. Due to impact damage, airframe electrical power could not be obtained. An external battery was attached to the fuel pump positive and negative wires, and the fuel pump actuated normally. The left and right wings were examined, and the fuel vents were free of debris. The PT6A-34AG engine, serial number PCEPH0183, was examined at the facilities of Pratt & Whitney, Bridgeport, West Virginia, on December 3, 2014. Theengine was installed on a test stand. All engine accessories remained intact. The chip plug detector was removed and found to be free of debris. The turbine blades and vanes were examined using a borescope, and exhibited normal operational signatures. The engine was installed within the engine run test cell using a slave starter and tach drive assembly. The engine was run for about 40 minutes at various power settings with no anomalies noted. ## Aircraft - Registration: [N502JS](https://openairdocs.org/deregistered/N502JS-2018-05-30), registration cancelled 2018-05-30, S/N 502B-0248, built 1994 (OpenAirDocs) - Reported make and model: AIR TRACTOR INC AT 502B (B) - Registry model: [Air Tractor AT-502B](https://openairdocs.org/model/air-tractor-at-502b) (registry code 0390307) (OpenAirDocs) - Registry engine: [Pratt & Whitney PT6A series](https://openairdocs.org/engine/pratt-whitney-pt6a-series) (registry code 52034, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 502B-0248 - Year built: 1994 - Airframe hours: 9313 - Engines: Pratt & Whitney PT6A-34AG 750 horsepower turbo prop - Damage: Substantial damage - Flight: Aerial application, Part 137 - Operator: Michaud Aviation - Registered owner: Michaud Kelly M DBA - Airworthiness certificate: Special, Restricted (Special) - Last inspection: Annual, February 10, 2014, 266 hours before - Departed: Princeton, CA - Destination: Princeton, CA - Airport: runway N, 2,500 × 65 ft, dirt ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 24; injuries: none; commercial; airplane ratings: single-engine land; medical: class 2, without waivers/limitations; last flight review November 26, 2013; seat: center; restraint: 4-point; flight hours: 1,453 total, 765 in this make and model, 1,363 as pilot in command, 249 in the last 90 days, 131 in the last 30 days, 8 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: variable at 4 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 73 °F, dew point 45 °F - Altimeter: 29.95 inHg - Observed at: KOVE, 20 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 20140613013949A](https://openairdocs.org/incident/20140613013949A), Jun 13, 2014: Air Tractor Inc AT-502B, Princeton, CA, Minor damage. On takeoff roll aircraft experienced partial loss of engine power. Heavyly loaded aircrft cold not sustain flight and departed runway into filed and rolled… ## Docket (4 files) The files NTSB released with the investigation on March 2, 2015, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=89442. 931 KB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 750 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40423039&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - Summary Report - Recovered Airframe and Engine Examination (item 2, .PDF, 58 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40423040&FileExtension=.PDF&FileName=Summary%20Report%20-%20Recovered%20Airframe%20and%20Engine%20Examination-Master.PDF - Summary Report - Recovered Engine Run (item 3, .PDF, 55 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40423041&FileExtension=.PDF&FileName=Summary%20Report%20-%20Recovered%20Engine%20Run-Master.PDF - Release of Aircraft Wreckage, NTSB Form 6120.15 (item 4, .PDF, 68 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40423042&FileExtension=.PDF&FileName=Release%20of%20Aircraft%20Wreckage,%20NTSB%20Form%206120.15-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.