Amateur-built REVOLUTION MINI 500 accident near Cahokia, Illinois, September 19, 1998
On September 19, 1998 at about 6:30 pm local time, a amateur-built REVOLUTION MINI 500 (helicopter), registered N611AB, was destroyed in an accident near Cahokia, Illinois (St. Louis Downtown Parks airport). It was a personal flight under general aviation rules (Part 91). 1 person was killed. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
A loss of engine power due to cold seizure of the power-takeoff cylinder. A factor contributing to the accident was the power lines.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- September 19, 1998 · about 6:30 pm local time
- Place
- Cahokia, Illinois · St. Louis Downtown Parks · map
- Type
- Accident
- Injuries
- 1 person was killed.
- Weather
- visual conditions (good weather)
- Aircraft
- Amateur-built REVOLUTION MINI 500 REVOLUTION
- Registration
- N611AB · registry record · serial 0294
- Damage
- Destroyed
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
A witness watched the helicopter as it climbed out after takeoff. The witness said that the helicopter was higher than the telephone lines which ran northeast of the airport. 'He was level and climbing, going away from me when all of a sudden, the sound (engine sound) went quiet, followed by a pop. It was not a loud pop.' The helicopter began a shallow descent. At about 30 to 40 feet above the field, the helicopter 'leveled out,' but 'kept coming down.' The witness said he saw the helicopter 'hit' and then 'cartwheel.' Examination of the helicopter's engine revealed scoring marks on the power-takeoff cylinder (front cylinder) piston, and impact marks in the head. Small metallic particles were embedded in the piston head. The power-takeoff cylinder wall showed scuff marks, and the cylinder head showed impact marks. The two power-takeoff spark plugs' showed no gap at the electrodes, and impact marks. No other anomalies were revealed.
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: flight instructor, commercial pilot
- Ratings: multi-engine land; single-engine land; instructor: helicopter; instrument: airplane; instrument: helicopter; rotorcraft: gyroplane; rotorcraft: helicopter
- Flight time: 28,000 hours in all
- Medical certificate: Class 2 (valid medical--w/ waivers/lim.)
- Seat: frt
The aircraft
- Airframe total time: 96 hours
- Last inspection: annual inspection, June 30, 1998; 21 hours since
- Maximum gross weight: 840 lb
- Seats: 1
- Landing gear: fixed
- Engine: Rotax 582 (piston); 0 hours total
The flight
- Departed from: CPS at 6:23 pm
- Destination: 3SQ St. Charles MO
- Flight plan: none
- Runway 0
Weather at the time
- Light: daylight
- Wind: from 190° at 4 knots
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 82°F (28°C), dew point 63°F (17°C)
- Altimeter: 29.00 inHg
- Observation at 5:53 pm from STL, 15 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.