Grumman Acft Eng Cor-Schweizer G-164B accident near Amana, Iowa, July 19, 2021
On July 19, 2021 at about 7:10 pm local time, a 1976 Grumman Acft Eng Cor-Schweizer G-164B, registered N8422K, was substantially damaged in an accident during initial climb near Amana, Iowa (Amana airport). It was an aerial application (crop spraying) flight under agricultural flying rules (Part 137). No one was hurt; 1 person was on board or involved. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
The loss of engine power for reasons that could not be determined.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- July 19, 2021 · about 7:10 pm local time
- Place
- Amana, Iowa · Amana · map
- Type
- Accident
- Injuries
- No one was hurt; 1 person was on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Grumman Acft Eng Cor-Schweizer G-164B, built 1976 · all G-164Bs on the register
- Registration
- N8422K · registry record · serial 80B
- Damage
- Substantial damage
- Flight
- Aerial application (crop spraying) flight · agricultural flying rules (Part 137)
The NTSB's narrative final · quoted from the NTSB record
The pilot of the agricultural airplane reported that the airplane’s engine lost power shortly after takeoff. The airplane settled into the corn field off the departure end of the runway and nosed over. The airplane sustained substantial damage to its left wing and fuselage. All three propeller blades exhibited aft bending, bending opposite rotation, twisting toward low pitch and chordwise/rotational scoring predominately on the camber side which was consistent with impact at low power. Examination of the engine revealed a discontinuity in the drive system consisting of a broken torsion shaft. The broken torsion shaft is indicative of the engine operating at the time of impact. Examination of the fuel control unit and the propeller governor did not reveal any anomalies. No anomalies were found with respect to the engine, propeller, fuel control unit, or propeller governor that would explain the reported loss of engine power. Based on the results of testing and examination, the reason for the reported loss of engine power could not be determined.
The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.
The factual record from the NTSB's investigation tables, in plain English
What happened, in order
- Loss of engine power (total) during initial climb defining event
The NTSB's findings
- Not determined › Not determined › (general) › (general) › Unknown/Not determined
Pilot
- Certificate: flight instructor, commercial pilot
- Ratings: multi-engine land; single-engine land; instructor: airplane single-engine; instrument: airplane
- Flight time: 10,693 hours in all; 7,912.8 in this make and model; 343.6 in the last 90 days; 206.8 in the last 30 days
- Last flight review: April 18, 2021
- Medical certificate: Class 2 (with waivers/limitations)
- Seat: sngl
- Injury: no injuries
The aircraft
- Last inspection: annual inspection
- Seats: 1
- Landing gear: fixed
- Engine: Honeywell TPE-331 (turboprop); 0 hours total
- Operator: Thompson Aero INC
The flight
- Flight plan: none
- Runway 26, 2,600 ft by 95 ft
Weather at the time
- Light: daylight
- Wind: from 020° at 6 knots
- Visibility: 10 statute miles
- Sky: broken clouds at 4,100 ft
- Temperature: 82°F (28°C), dew point 64°F (18°C)
- Altimeter: 30.19 inHg
- Observation at 1:52 pm from KCID, 8 miles away
Weather report (METAR): KCID 191852Z 02006KT 10SM BKN041 BKN070 28/18 A3019 RMK AO2 SLP218 T02780178
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 1 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
5 documents, released by the NTSB on August 16, 2023. View them here, or download them; the NTSB redacts some personal details before release, and this site shows the NTSB's own titles rather than its file names.
| # | Document | What it is | |
|---|---|---|---|
| 1 | Powerplant Examination Report | PDF, 14 pages | View Download |
| 2 | Pilot/operator Aircraft Accident Report, NTSB Form 6120.1 | PDF, 9 pages | View Download |
| 3 | Statement of Party Representatives to NTSB INVESTIGATION-1 | PDF, 3 pages | View Download |
| 4 | Release of Aircraft Wreckage, NTSB Form 6120.15 | PDF, 1 page | View Download |
| 5 | Fuel Control Unit and Propeller Governor Test Sheets | PDF, 11 pages | View Download |
The same docket at the NTSB · documents without a copy here are fetched from the NTSB when you open them.
Other NTSB records under N8422K the same tail number, which may have belonged to a different aircraft at the time
Everything on this page comes from the NTSB's public records. The narrative, probable cause and findings are the NTSB's own words; the coded tables behind the report are written out in plain English, with pilots' ages, home towns and medical details left out. The documents and photographs are the NTSB's docket, shown as the NTSB released them. This site's own text never names anyone involved. A preliminary report can change; the final report usually follows one to two years later, and the page is refreshed when it does.