ASN Wikibase Occurrence # 214578
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| Date: | Tuesday 21 August 2018 |
| Time: | 08:50 |
| Type: |  Air Tractor AT-400 |
| Owner/operator: | Ross Seed Co DBA |
| Registration: | N7300M |
| MSN: | 400-0518 |
| Year of manufacture: | 1984 |
| Total airframe hrs: | 11932 hours |
| Engine model: | Pratt & Whitney PT6A SERIES |
| Fatalities: | Fatalities: 0 / Occupants: 1 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | Grand Forks, ND -
 United States of America
|
| Phase: | Manoeuvring (airshow, firefighting, ag.ops.) |
| Nature: | Agricultural |
| Departure airport: | East Grand Forks Airport, MN (MN81) |
| East Grand Forks Airport, MN (MN81) | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
The pilot was maneuvering the airplane during an aerial application over a field. A witness noticed that the airplane’s final turn was different than previous turns. Just before the airplane impacted the ground, the witness noticed a puff of smoke or liquid coming from the airplane. As the witness was a distance away, she was not certain. During the impact, the airplane sustained substantial damage.
Examination of the engine revealed circumferential rubbing marks due to contact between the compressor turbine disk assembly and power turbine (PT) disk assembly. Of the 41 PT blades, 18 were recovered, and those blades exhibited fracture surfaces consistent with overstress fracture under elevated temperatures. Impact marks were identified inside the exhaust duct. The fracture of these blades likely occurred at ground impact when the engine was operational.
It is likely that one or more of the unrecovered PT blades failed for an undetermined reason during the flight and impacted adjacent PT blades and components, including the exhaust duct. The internal engine damage from the released blades caused the PT disc assembly to fail, resulting in a loss of engine power.
Probable Cause: The loss of engine power while maneuvering due to the failure of the power turbine blade assembly for reasons that could not be determined based on available evidence.
Accident investigation:
 |
|
Sources:
https://www.grandforksherald.com/news/accidents/4488391-small-plane-crashes-field-north-grand-forks
http://knoxradio.com/news/local/gf-plane-crash
http://www.valleynewslive.com/content/news/Downed-Crop-Duster-North-of-Grand-Forks-491368161.html
NTSB
http://registry.faa.gov/aircraftinquiry/NNum_Results.aspx?NNumbertxt=7300M
https://www.jetphotos.com/photo/6210629 (photo)
Location
Images:
Photo: NTSB
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 21-Aug-2018 16:47 | Geno | Added |
| 21-Aug-2018 18:24 | KLAS | Updated [Aircraft type] |
| 21-Aug-2018 23:22 | Geno | Updated [Aircraft type, Registration, Cn, Operator, Source] |
| 21-Jun-2022 21:46 | Captain Adam | Updated [Time, Location, Departure airport, Destination airport, Source, Narrative, Category, Accident report, Photo] |
Corrections or additions? ... Edit this accident description
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