Bell 47G-5 accident near Nunda, South Dakota, October 6, 1996
On October 6, 1996 at about 1:00 pm local time, a Bell 47G-5 (helicopter), registered N7925J, was substantially damaged in an accident near Nunda, South Dakota. 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).
The NTSB's probable cause their words, unchanged
failure of maintenance personnel to properly torque the six accessory drive bolts, which resulted in fatigue failure of the undertorqued bolts.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- October 6, 1996 · about 1:00 pm local time
- Place
- Nunda, South Dakota · map
- Type
- Accident
- Injuries
- No one was hurt; 1 person was on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Bell 47G-5 · all 47G-5s on the register
- Registration
- N7925J · registry record · serial 25041
- Damage
- Substantial damage
- Flight
- Aerial application (crop spraying) flight · agricultural flying rules (Part 137)
The NTSB's narrative final · quoted from the NTSB record
During the second agricultural load, a total loss of engine power occurred, and the pilot made an autorotative landing, but the helicopter was damaged during the occurrence. Examination of the engine revealed failure of six bolts that attached the accessory drive gear to the crankshaft. Further examination of the attachment bolts revealed that fatigue cracking had occurred. There was evidence that inadequate pre-load torque had been applied to the assembly. The engine had approximately 400 hours since its last overhaul.
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; instructor: helicopter; rotorcraft: helicopter
- Flight time: 2,600 hours in all; 1,100 in this make and model; 320 in the last 90 days; 160 in the last 30 days; 2,488 as pilot in command; 5 on instruments
- Medical certificate: Class 2 (valid medical--w/ waivers/lim.)
- Seat: left
The aircraft
- Airframe total time: 5,546 hours
- Last inspection: annual inspection, April 15, 1996; 426 hours since
- Maximum gross weight: 2,800 lb
- Seats: 2
- Landing gear: fixed
- Engine: Lycoming VO-435-A (piston); 0 hours total
The flight
- Departed from: SD18 Flandreau SD at 12:15 pm
- Flight plan: none
- Runway 0
Weather at the time
- Light: daylight
- Wind: from 340° at 7 knots
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 48°F (9°C), dew point 43°F (6°C)
- Altimeter: 30.00 inHg
- Observation at 12:54 pm from BKX
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.
Other NTSB records under N7925J the same tail number, which may have belonged to a different aircraft at the time
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.