Bell 206L3 accident near Boise, Idaho, May 27, 1997
On May 27, 1997 at about 6:10 pm local time, a Bell 206L3 (helicopter), registered N35CH, was substantially damaged in an accident near Boise, Idaho (Gowen 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 improper torque meter installation by maintenance personnel, attempting flight with known discrepancies by the pilot-in-command and the check airman, and an improper autorotation by the pilot-in-command with improper oversight of the autorotation maneuver by the check airman.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- May 27, 1997 · about 6:10 pm local time
- Place
- Boise, Idaho · Gowen Field · map
- Type
- Accident
- Injuries
- No one was hurt; 3 people were on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Bell 206L3 · all 206L3s on the register
- Registration
- N35CH · no longer on the register · serial 51335
- 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 pilot was executing an autorotation maneuver for a FAR Part 135 flight check. This autorotation maneuver was to be a 180-degree reversal autorotation to a predetermined spot landing with a power termination. The pilot executed the maneuver, but during the level-off received a low RPM warning horn, and attempted to recover using power. During the attempt to increase power the helicopter's throttle interfered with a nut which had been installed for an external torque meter approximately one week before the accident. The nut on the torque meter installation interfered with the throttle controls in certain positions only. A discrepancy with the helicopter's throttle was noticed by the pilot-in-command, and reported to the FAA examiner before the beginning of the flight check.
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: airline transport pilot, commercial pilot
- Ratings: single-engine land; rotorcraft: helicopter
- Flight time: 7,860 hours in all; 625 in this make and model; 10 in the last 90 days; 3 in the last 30 days; 7,050 as pilot in command
- Medical certificate: Class 2 (valid medical--no waivers/lim.)
- Seat: rgt
The aircraft
- Airframe total time: 3,202 hours
- Last inspection: annual inspection, February 2, 1997
- Maximum gross weight: 4,150 lb
- Seats: 7
- Landing gear: fixed
- Engine: Allison 250-C30P (turboshaft); 0 hours total
The flight
- Departed from: BOI ID at 5:00 pm
- Destination: BOI
- Flight plan: none
- Runway 0
- A second pilot was aboard
Weather at the time
- Light: daylight
- Visibility: 40 statute miles
- Sky: clear
- Temperature: 70°F (21°C), dew point 0°F (-18°C)
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 2 | |||
| 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.