Amateur-built MONI accident near Joliet, Illinois, July 7, 1984
On July 7, 1984 at about 9:00 pm local time, a amateur-built MONI, registered N157LG, was substantially damaged in an accident near Joliet, Illinois (Wilhelmi airport). It was a personal flight under general aviation rules (Part 91). 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 NTSB has not yet published a probable cause for this accident. Investigations usually take one to two years; this page updates when the final report is released.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- July 7, 1984 · about 9:00 pm local time
- Place
- Joliet, Illinois · Wilhelmi · map
- Type
- Accident
- Injuries
- No one was hurt; 1 person was on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Amateur-built MONI
- Registration
- N157LG · registry record · serial 157
- Damage
- Substantial damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
THE PROP SEPARATED FROM THE ACFT AT APRX 500 FT AGL DURING THE INITIAL TAKEOFF CLIMB. A FORCED LANDING WAS MADE IN A CORN FIELD. THE PROP WAS ATTACHED BY MEANS OF 4 5/16 INCH BOLTS AND RETAINING NUTS. TWO OF THE FOUR BOLT PORTIONS REMAINING AFTER THE ACCIDENT WERE REMOVED. ONE OF WHICH WAS TESTED AND PROGRESSIVE FATIGUE WAS FOUND. THE KIT MANUFACTURER LATER ISSUED A SERVICE BULLETIN STATING THAT WITH THE NUTS PROPERLY TORQUED IT IS POSSIBLE FOR THE NUTS TO BOTTOM OUT ON THE BOLT THREADS WHICH WOULD RESULT IN THE BOLTS SHEARING. THE MANUFACTURER SUGGESTS INSTALLING WASHERS AT THE HEAD OF THE BOLT TO PREVENT THE NUT FROM BOTTOMING OUT.
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
Pilot
- Certificate: commercial pilot
- Ratings: single-engine land; instrument: airplane
- Flight time: 30 in this make and model
- Medical certificate: Class 3 (valid medical--w/ waivers/lim.)
- Seat: unk
The aircraft
- Airframe total time: 30 hours
- Last inspection: annual inspection, September 22, 1983
- Maximum gross weight: 560 lb
- Seats: 1
- Landing gear: fixed
- Engine: Kfm 107E (piston); 0 hours total
The flight
- Destination: UGN Waukegan IL
- Flight plan: none
- Runway 0
Weather at the time
- Light: daylight
- Wind: from 080° at 8 knots
- Visibility: 15 statute miles
- Sky: scat at 6,000 ft
- Temperature: 70°F (21°C), dew point 45°F (7°C)
- Altimeter: 29.00 inHg
- Observation at 7:50 pm from MDW, 23 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 1 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
The docket, the folder of records gathered during an investigation (maintenance records, photographs, witness statements, examinations), has not been read from the NTSB for this case yet; the list appears here once it has. Open the docket at the NTSB.
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.