# NTSB CHI99LA258: Air Tractor 401B, N6006A, Mccanna, ND, July 24, 1999 - Type: NTSB accident investigation - Classification: Accident · Serious injuries · Limited investigation · Final report - Date: July 24, 1999, 18:30 local (23:30 UTC) - Place: Mccanna, ND - Coordinates: 47.899818, -97.619682 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=47.8998&lon=-97.6197&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Highest injury: Serious injuries - Injuries: 1 serious - Status: Completed, report December 4, 2000 - Report: Approved by Office Director - NTSB case key (mKey): 46901 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CHI99LA258 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/46901/pdf - Page: https://openairdocs.org/ntsb/CHI99LA258 ## Probable cause the inadvertent stall by the pilot. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - In flight collision with terrain/water, maneuvering - aerial application - stall - inadvertent, pilot in command (cause) - misc eqpt/furnishings,seat belt - frayed - misc eqpt/furnishings,seat belt - separation ## Analysis The airplane impacted terrain while spraying a potato field. The pilot reported that the airplane stalled during a right turn. ## Factual narrative On July 24, 1999, at 1830 central daylight time, an Air Tractor 401B, N6006A, operated by Bakke Flying Service, received substantial damage on impact with terrain while spraying a potato field located approximately 2 miles north of McCanna, North Dakota. Visual meteorological conditions prevailed at the time of the accident. The 14 CFR Part 137 agricultural flight was not operating on a flight plan. The pilot sustained serious injuries. The flight originated from the Bakke Airstrip, Larimore, North Dakota, at 1815. In a written statement, the pilot reported the following: "July 24 it was hot and humid and flying was not very good wind was light I was spraying the south half of the field going back and forth from the north to south. I was on my 4 or 5 pass on the east end making right turns. In my last right turn the aircraft stalled and hit the ground. ..." The left shoulder harness was found separated following the accident. The shoulder harness was removed and sent to the National Transportation Safety Board's (NTSB's) Materials Laboratory for examination. The NTSB's Material Report stated. "...Generally the harness appeared to be of uniform coloration...". Three sections of the harness were removed and delivered to an independent testing laboratory for tensile testing. The test results for the three sections indicated ultimate loads of 4,920 lbs, 4,760 lbs, 4,670 lbs. The test report also stated, "...In all three cases the failure initiated in the harness adjacent to the double "X" stitching .. A test certificate ... indicated that a harness, part number 500702-403, was tested on April 13, 1989 for Air Tractor. It had a rated strength of 1,500 pounds and failed at 3,300 pounds when an end fitting broke. Testing was reported as in compliance with TSO-C22E (NAS 802), single occupancy." The separated ends of the left shoulder harness had, "...numerous individual filaments protruding from the surface almost obscuring the pattern of the strands..." The area containing the protruding filaments extended approximately one inch below the separated ends above which was the harnesses adjusting roller. Areas along the separated ends exhibited "horsetailing". According to the Materials Laboratory Factual Report,"..."Horsetailing" is a product of the material properties and the differences in the energy stored during separation." The airplane's date of manufacture was 1995. Air Tractor Service Letter #152 applicable for all Air Tractor models and serial numbers states, "... Color fading is an indication of deterioration due to ultraviolet light exposure. Faded or frayed harnesses should be replaced immediately We recommend that the shoulder harness be replaced every five years...". ## Aircraft - Registration: [N6006A](https://openairdocs.org/deregistered/N6006A-2001-10-12), registration cancelled 2001-10-12, S/N 401B-0984, built 1995 (OpenAirDocs) - Reported make and model: Air Tractor 401B - 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: 0984 - Airframe hours: 1200 - Engines: P&W AN2 1340 600 horsepower reciprocating - Damage: Substantial damage - Flight: Aerial application, Part 137 - Registered owner: Bakke Flying Service - Airworthiness certificate: Special, Restricted (Special) - Last inspection: Annual, October 20, 1998, 300 hours before - Departed: PVT, ND ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 35; commercial; airplane ratings: single-engine land; medical: class 2, valid medical--no waivers/lim.; seat: center; flight hours: 4,500 total, 500 in this make and model, 4,450 as pilot in command, 300 in the last 90 days, 100 in the last 30 days, 18 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 150° at 8 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 81 °F, dew point 63 °F - Altimeter: 29.00 inHg - Observed at: GFK, 21 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 19990724009639A](https://openairdocs.org/incident/19990724009639A), Jul 24, 1999: Mccana, ND, Substantial damage. Acft stalled during aerial application and crashed, other circumstances ae unknown. (-23)the aircraft was being operated in commerical aerial application… 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.