Grumman G-164A accident near Patoka, Illinois, July 22, 2023
On July 22, 2023 at about 4:13 pm local time, a 1974 Grumman G-164A, registered N9892, was substantially damaged in an accident during maneuvering (low-alt flying) near Patoka, Illinois. 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).
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The NTSB's probable cause their words, unchanged
A partial loss of engine power due to the failure of two compressor turbine blades as a result of the engine operating near or above the engine’s operating limits for an undetermined amount of time beyond the recommended engine’s TBO limit, which led to material creep and overload failure.
Source: NTSB aviation accident database, copy made October 4, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- July 22, 2023 · about 4:13 pm local time
- Place
- Patoka, Illinois · map
- Type
- Accident
- Injuries
- No one was hurt; 1 person was on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Grumman G-164A, built 1974 · all G-164As on the register
- Registration
- N9892 · registry record · serial 1324
- Damage
- Substantial damage
- Flight
- Aerial application (crop spraying) flight · agricultural flying rules (Part 137)
The NTSB's narrative final · quoted from the NTSB record
While conducting an aerial application flight, the pilot observed a loss of engine power. Because the airplane was at a low altitude and its airspeed was decreasing, the pilot performed a forced landing in a corn field, which resulted in the airplane sustaining substantial damage to both wings, the fuselage, and empennage. An examination of the airplane’s turboprop engine showed rotational scoring, hard body impact damage, and missing material throughout the compressor turbine (CT) and power turbine (PT) sections of the engine, indicating that the engine was producing some level of power at the time of impact. Multiple CT blades were fractured above the blade platform and about 75% of the PT blades were fractured at various lengths above the blade platform. Metallurgical examination of two of the fractured CT blades showed material necking near the fracture surfaces, microstructural rafting, creep voids, and localized alteration of the microstructure that is consistent with heat-related material degradation. Examination of the fuel control unit showed the maximum Ng speed adjustment screw was adjusted to the maximum fuel flow position and lock-wired in place. Based on the condition of the blades, the loss of engine power was likely due to the failure of two CT blades as a result of the engine being operated near or above the engine’s operating limits for an undetermined amount of time beyond the recommended engine’s time between overhaul (TBO) limit; this led to material creep and the overload failure of the CT blades.
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 (partial) during maneuvering (low-alt flying) defining event
The NTSB's findings
- Aircraft › Aircraft power plant › Engine (turbine/turboprop) › Compressor section › Failure
- Aircraft › Aircraft power plant › Engine (turbine/turboprop) › (general) › Incorrect use/operation
Pilot
- Certificate: commercial pilot
- Ratings: single-engine land
- Flight time: 16,442 hours in all; 16,261 in this make and model; 1,591 as pilot in command
- Last flight review: March 13, 2023
- Medical certificate: Class 2 (without waivers/limitations)
- Seat: ctr
- Injury: no injuries
The aircraft
- Airframe total time: 14,217 hours
- Last inspection: annual inspection, May 9, 2023
- Maximum gross weight: 6,369 lb
- Seats: 1
- Landing gear: fixed
- Engine: Pratt And Whitney Canada PT6-20A (turboprop); 14,092 hours total
- Operator: Redditt Air Service INC
The flight
- Departed from: SLO Salem IL at 3:50 pm
- Destination: SLO Salem IL
- Flight plan: none
Weather at the time
- Light: daylight
- Wind: from 360° at 3 knots
- Visibility: 10 statute miles
- Sky: scat at 8,000 ft
- Temperature: 79°F (26°C), dew point 64°F (18°C)
- Altimeter: 29.97 inHg
- Observation at 11:15 am from KAJG, 14 miles away
Weather report (METAR): KAJG 221615Z AUTO 36003KT 10SM SCT080 26/18 A2997 RMK AO2 T02640181
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flig | 1 |
Other NTSB records under N9892 the same tail number, which may have belonged to a different aircraft at the time
About this page
Everything above comes from the NTSB's public accident database: the narrative, probable cause and findings are the NTSB's own words, and the coded tables behind its report (pilot, aircraft, flight, weather, injuries, sequence of events) are written out in plain English. Pilots' ages, home towns and medical details are left out on purpose. The docket at the NTSB holds the report as a PDF and the investigation's photographs and documents. This site never names pilots, passengers or anyone else involved. A preliminary report describes what is known soon after the event and can change; the final report, with the probable cause, usually follows one to two years later and this page is refreshed when it does. Case number CEN23LA317.