Mbb BK-117 accident near Topeka, Kansas, August 28, 1998
On August 28, 1998 at about 3:53 pm local time, a Mbb BK-117 (helicopter), registered N230H, was substantially damaged in an accident near Topeka, Kansas (Forbes Field). It was a flight of an unrecorded kind under general aviation rules (Part 91). No one was hurt; 3 people were on board or involved. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
the pilot's failure to assure the engine cowling was secured during the aircraft preflight which resulted in the cowling separating from the helicopter and damaging the main rotor and tail rotor system. Factors associated with the accident were the cowling not being secured and inadequate design of the latching system by the manufacturer.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- August 28, 1998 · about 3:53 pm local time
- Place
- Topeka, Kansas · Forbes Field
- Type
- Accident
- Injuries
- No one was hurt; 3 people were on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Mbb BK-117
- Registration
- N230H · registry record · serial BK-117-A4
- Damage
- Substantial damage
- Flight
- Flight of an unrecorded kind · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
The accident occurred on a maintenance test flight after having had the No. 1 engine replaced. When returning from the flight a 'severe bump' and 'loud bang' were experienced followed by the helicopter rotating to the right. A pilot landed the helicopter in a field during which time it rolled over on its left side. Post accident inspection revealed the No. 1 engine cowling separated from the helicopter inflight. This damaged the main rotor blades which resulted in an imbalance and subsequent loss of the tail rotor gear box. Both Hartwell cowling latches appeared in the closed position; however, the aft latch was not damaged as was the forward latch. The manufacturer is aware of similar problems and has issued service bulletins addressing the problems. The latest service bulletin, SB-MBB-BK 117-20-109, had not been incorporated on the accident helicopter.
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: helicopter; rotorcraft: helicopter
- Flight time: 6,401 hours in all; 476 in this make and model; 65 in the last 90 days; 35 in the last 30 days; 5,563 as pilot in command
- Medical certificate: Class 2 (valid medical--w/ waivers/lim.)
- Seat: rgt
The aircraft
- Airframe total time: 3,928 hours
- Last inspection: approved inspection programme, August 13, 1998; 31 hours since
- Maximum gross weight: 3,200 lb
- Seats: 5
- Landing gear: fixed
- Engine: Lycoming LTS-101-650B1 (turboshaft); 0 hours total
The flight
- Departed from: FOE at 3:40 pm
- Flight plan: none
- Runway 0
Weather at the time
- Light: daylight
- Wind: from 300° at 5 knots
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 79°F (26°C), dew point 68°F (20°C)
- Altimeter: 30.00 inHg
- Observation at 3:53 pm from FOE
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 3 |
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.