Amateur-built Rotorway Exec 90 accident near Kalamazoo, Michigan, April 28, 2007
On April 28, 2007 at about 4:52 pm local time, a amateur-built Rotorway Exec 90 (helicopter), registered N52988, was destroyed in an accident near Kalamazoo, Michigan. It was a personal flight under general aviation rules (Part 91). No one was hurt; 2 people were on board or involved. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
The failure of the sprag clutch which resulted in the disengagement of the drive unit and the pilot's misjudged landing during the autorotation. A factor was the low altitude at which the failure occurred.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- April 28, 2007 · about 4:52 pm local time
- Place
- Kalamazoo, Michigan · map
- Type
- Accident
- Injuries
- No one was hurt; 2 people were on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Amateur-built Rotorway Exec 90
- Registration
- N52988 · no longer on the register · serial 1
- Damage
- Destroyed
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
The helicopter was destroyed by impact forces and a post crash fire while attempting an auto-rotation after a mechanical failure. The pilot stated that he was practicing takeoffs, hovering, and quick stops above the runway. After takeoff, at about 50 feet and 50mph, he lowered the collective to initiate a quick stop. At this point the engine RPM revved up out of control. He pulled up on the collective to re-engage the drive system, but the system would not engage. He entered into an auto-rotation, and as he neared the ground the helicopter began to slide sideways, folding the skids under the helicopter. The helicopter then rolled on its side, and the occupants climbed out prior to the post crash fire. Subsequent examination of the helicopter's drive system revealed that the drive shafts, pulleys, and drive belts were intact. The only device within the helicopter drive system that could not be determined to be in working condition was the sprag clutch which transmits engine power to the rotor drive system. The sprag clutch was not examined during the course of the investigation.
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: private
- Ratings: single-engine land; rotorcraft: helicopter
- Flight time: 463 hours in all; 433 in this make and model; 2 in the last 90 days
- Medical certificate: Class 3 (with waivers/limitations)
- Injury: minor injuries
The aircraft
- Landing gear: fixed
- Engine: Rotorway RI-162 (piston); 0 hours total
- Fire on the ground
The flight
- Departed from: 4N0 Kalamazoo MI
- Flight plan: none
- Runway 18, 2,697 ft by 125 ft
Weather at the time
- Light: daylight
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 63°F (17°C), dew point 46°F (8°C)
- Altimeter: 29.87 inHg
- Observation at 4:53 pm from KAZO, 9 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 1 | |||
| Passengers | 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.