Cessna A188B accident near Suring, Wisconsin, July 16, 2009
On July 16, 2009 at about 11:40 am local time, a Cessna A188B, registered N9747G, was substantially damaged in an accident during maneuvering (low-alt flying) near Suring, Wisconsin. 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 loss of engine power resulting from the fatigue failure of the crankshaft due to the loss of engine case through-bolt torque. Contributing to the engine failure was the operator's failure to overhaul the engine in accordance with the manufacturer's recommended guidelines.
Source: NTSB aviation accident database, copy made October 4, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- July 16, 2009 · about 11:40 am local time
- Place
- Suring, Wisconsin · map
- Type
- Accident
- Injuries
- No one was hurt; 1 person was on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Cessna A188B · all A188Bs on the register
- Registration
- N9747G · registry record · serial 18801587T
- 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 reported that the engine began to run very rough during a turn at low altitude. The engine suddenly seized so he made an emergency landing to a wheat field. During the landing, the left main gear collapsed and the left wing and nose of the aircraft dug into the soft soil, sustaining substantial damage. A teardown inspection of the engine revealed fretting wear scars on the crankcase backbone between the number two and three main bearing supports, and the number one, two, and three camshaft journal supports. The number one, two, three, four, and five main crankshaft main bearing supports exhibited fretting wear scars, and the number two and three supports exhibited mechanical damage from bearing shift and rotation. Additionally, the number two intermediate crankshaft main bearings had extruded from their crankshaft positions in the left and right case halves. An unapproved red sealant had been applied to the crankcase backbone. The above signatures are all consistent with an engine crankcase assembly that had lost its through-bolt torque. The crankshaft was fractured through at the number four short cheek between the number two main bearing journal and the number three connecting rod journal. A metallurgical examination of the fracture surface revealed crack arrest marks, which were indicative of a fatigue fracture which emanated from the surface of the number two main bearing journal. The heat treatment of the crankshaft met the manufacturer’s specifications. An examination of the engine logbooks revealed that the engine’s total time was about 1,778 hours and it had about 500 hours since the last major overhaul. The engine’s last overhaul was conducted on September 30, 1986, almost 23 years since the last major overhaul. The engine manufacturer recommends that when the aircraft is used in aerial spraying, the engine be overhauled after an accumulation of 1,200 hours or twelve (12) years, whichever occurs first.
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 maneuvering (low-alt flying) defining event
- Collision with terrain or object (not controlled flight into terrain) during landing (landing roll)
The NTSB's findings
- cause Aircraft › Aircraft power plant › Engine (reciprocating) › Recip engine power section › Fatigue/wear/corrosion
- cause Aircraft › Aircraft power plant › Engine (reciprocating) › Recip engine power section › Failure
- factor Aircraft › Aircraft power plant › Engine (reciprocating) › Recip engine power section › Incorrect service/maintenance
- factor Personnel issues › Action/decision › Action › Incorrect action performance › Owner/builder
- factor Personnel issues › Task performance › Maintenance › (general) › Owner/builder
Pilot
- Certificate: flight instructor, commercial pilot
- Ratings: multi-engine land; single-engine land; instructor: airplane single-engine; instrument: airplane
- Flight time: 3,800 hours in all; 50 in this make and model; 94 in the last 90 days; 18 in the last 30 days; 3,660 as pilot in command; 250 on instruments
- Last flight review: February 5, 2009
- Medical certificate: Class 2
- Seat: ctr
- Injury: no injuries
The aircraft
- Airframe total time: 2,211 hours
- Last inspection: annual inspection, October 23, 2008
- Maximum gross weight: 4,200 lb
- Seats: 1
- Landing gear: fixed
- Engine: Continental IO-520-D (piston); 0 hours total
- Operator: Nicolet Air LLC
The flight
- Departed from: Suring WI at 11:20 am
- Destination: Private Field WI
- Flight plan: none
Weather at the time
- Light: daylight
- Wind: from 260° at 5 knots
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 55°F (13°C), dew point 52°F (11°C)
- Altimeter: 29.87 inHg
- Observation at 11:10 am from GRB, 30 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flig | 1 |
Other NTSB records under N9747G 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 CEN09LA447.