Sunday, September 30, 2018

Air Tractor AT-502B, registered to and operated by Red Willow Aviation Spraying Inc, N61267: Accident occurred August 27, 2015 in Monroe, Platte County, Nebraska

The National Transportation Safety Board did not travel to the scene of this accident.

Additional Participating Entities:
Federal Aviation Administration / Flight Standards District Office; Lincoln, Nebraska
Air Tractor Inc; Olney, Texas
GE Engines; Cincinnati, Ohio
AAII of the Czech Republic; Prague

Aviation Accident Factual Report - National Transportation Safety Board:

Investigation Docket - National Transportation Safety Board:

Location: Monroe, NE
Accident Number: CEN15LA389
Date & Time: 08/27/2015, 1200 CDT
Registration: N61267
Aircraft Damage: Substantial
Defining Event: Loss of engine power (partial)
Injuries: 1 Minor
Flight Conducted Under: Part 137: Agricultural 

On August 27, 2015, about 1200 central daylight time, an Air Tractor, AT-502B, single-engine turboprop airplane, N61267, had a partial loss of engine power during low-altitude maneuvering flight and impacted terrain near Monroe, Nebraska. The pilot sustained minor injuries and the airplane sustained substantial damage to both wings, the horizontal stabilizer, and elevator. The airplane was registered to, and was operated by Red Willow Aviation Spraying, Inc.; McCook, Nebraska, as a 14 Code of Federal Regulations Part 137 aerial application flight. Day visual meteorological conditions prevailed, and a flight plan had not been filed for the local flight which had departed about 1130 from Genoa Municipal Airport (97Y), Genoa, Nebraska.

The pilot was seeding a cover crop into corn when he experienced a partial loss of engine power. The engine instruments showed the engine was operating, but was producing less than idle power. The pilot pushed the throttle to full power, with no effect. At that point, he knew he had to land. The pilot turned the airplane into the wind and lowered the flaps. As he heard corn start hitting the bottom of the airplane, the pilot pulled the control stick full aft to stall the airplane. The left wing dropped, the airplane turned 90 degrees, and impacted the ground sideways. The right wing subsequently struck the ground and the airplane came to rest upright. The engine continued to run until the pilot shut it down and exited the airplane.

An examination of the wreckage showed there was adequate fuel on-board, there was no fuel spill, and no postimpact fire. The airplane's engine and propeller governor were examined and no anomalies were found. The fuel control unit and fuel pump were removed and sent to the manufacturer in Prague, Czech Republic, for examination. A Turbine Start Limit and Monitor (TSLM) and a USB thumb drive, which contained Global Positioning Satellite (GPS) data from a GPS unit on board the airplane, were sent to the NTSB Vehicle Recorder's Laboratory for examination.

The examination of the fuel control unit and fuel pump revealed no anomalies.

The GPS data on the USB thumb drive was examined and did not include the accident flight. The TSLM, which monitors internal turbine temperature, N1, N2, torque, oil pressure, and bus voltage, and records at engine startup and when the parameters are exceeded, recorded 74 events. Event 74 was triggered by the N1 parameter being set above the user set upper limit. The exceedance ended 1.5 seconds into the event. Following the exceedance, the internal turbine temperature, N1, and N2 (propeller rpm) decreased over time, consistent with a lower output by the engine.

The TSLM data was reviewed by the engine manufacturer who concluded that the propeller went into feather either by an incorrect pilot command or a governor problem. The manufacturer also noted the engine was being operated above the manual temperature limits at the time of the event and the internal turbine temperature and core speed did not correlate correctly. The manufacturer could only attribute that to scaling of the data or improper engine operation.

Pilot Information

Certificate: Commercial
Age: 38
Airplane Rating(s): Single-engine Land
Seat Occupied: Single
Other Aircraft Rating(s): None
Restraint Used: 4-point
Instrument Rating(s): None
Second Pilot Present: No
Instructor Rating(s): None
Toxicology Performed: No
Medical Certification: Class 2 With Waivers/Limitations
Last FAA Medical Exam: 01/07/2015
Occupational Pilot: Yes
Last Flight Review or Equivalent:
Flight Time:  (Estimated) 1400 hours (Total, all aircraft), 970 hours (Total, this make and model) 

Aircraft and Owner/Operator Information

Aircraft Make: AIR TRACTOR INC
Registration: N61267
Model/Series: AT 502B
Aircraft Category: Airplane
Year of Manufacture: 1995
Amateur Built: No
Airworthiness Certificate: Restricted
Serial Number: 502B-0303
Landing Gear Type: Tailwheel
Seats: 1
Date/Type of Last Inspection: 11/17/2014, Annual
Certified Max Gross Wt.: 9400 lbs
Time Since Last Inspection: 311 Hours
Engines: 1 Turbo Prop
Airframe Total Time:
Engine Manufacturer: WALTER
Engine Model/Series: M601E11
Rated Power: hp
Operating Certificate(s) Held: Agricultural Aircraft (137)
Operator Designator Code: RIYG

Meteorological Information and Flight Plan

Conditions at Accident Site: Visual Conditions
Condition of Light: Day
Observation Facility, Elevation: KOLU, 1447 ft msl
Distance from Accident Site: 14 Nautical Miles
Observation Time: 1155 CDT
Direction from Accident Site: 110°
Lowest Cloud Condition: Clear
Visibility:  10 Miles
Lowest Ceiling: None
Visibility (RVR):
Wind Speed/Gusts: 9 knots / 14 knots
Turbulence Type Forecast/Actual: /
Wind Direction: 120°
Turbulence Severity Forecast/Actual: /
Altimeter Setting: 29.98 inches Hg
Temperature/Dew Point: 24°C / 18°C
Precipitation and Obscuration: No Obscuration; No Precipitation
Departure Point: GENOA, NE (97Y)
Type of Flight Plan Filed: None
Destination: GENOA, NE (97Y)
Type of Clearance: None
Departure Time:  CDT
Type of Airspace: Class G

Wreckage and Impact Information

Crew Injuries: 1 Minor
Aircraft Damage: Substantial
Passenger Injuries: N/A
Aircraft Fire: None
Ground Injuries: N/A
Aircraft Explosion: None
Total Injuries: 1 Minor
Latitude, Longitude:  41.513611, -97.646944 (est)

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