Bell UH-1B accident near Pierce, Idaho, September 23, 1993
On September 23, 1993 at about 3:15 pm local time, a Bell UH-1B (helicopter), registered N3979C, was substantially damaged in an accident near Pierce, Idaho. It was an other work-use flight under external-load helicopter rules (Part 133). 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
SEPARATION OF THE 90 DEGREE GEARBOX AFTER FATIGUE FAILURE OF THE GEARBOX ATTACH BOLTS. FACTORS INCLUDE HILLY/MOUNTAINOUS TERRAIN.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- September 23, 1993 · about 3:15 pm local time
- Place
- Pierce, Idaho · map
- Type
- Accident
- Injuries
- No one was hurt; 1 person was on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Bell UH-1B · all UH-1Bs on the register
- Registration
- N3979C · no longer on the register · serial 62-2048
- Damage
- Substantial damage
- Flight
- Other work-use flight · external-load helicopter rules (Part 133)
The NTSB's narrative final · quoted from the NTSB record
WHILE MANEUVERING NEAR A REFUELING SITE IN HILLY/MOUNTAINOUS TERRAIN, THE 90 DEGREE GEARBOX SEPARATED FROM THE AIRCRAFT. THE PILOT THEN ATTEMPTED A RUN-ON FORCED LANDING ON A NEARBY LOGGING ROAD. DURING THE FLARE, THE AIRCRAFT LANDED HARD, RESULTING IN A COLLAPSE OF THE SKIDS, AND SEPARATION OF THE REMAINING PORTION OF THE TAIL BOOM. METALLURGICAL ANALYSIS REVEALED THAT ALL SIX GEARBOX ATTACH BOLTS HAD EXPERIENCED REVERSE-BENDING FATIGUE FAILURE. THE OPERATOR RECORDS INDICATED THAT THIS WAS A NEW SURPLUS PART WHICH HAD 136 HOURS OF OPERATION SINCE NEW. HISTORICAL RECORDS CONFIRMING THE UNIT'S TOTAL TIME SINCE BEING SHIPPED TO THE PHILIPPINES AS A NEW SURPLUS PART IN 1981 COULD NOT BE LOCATED.
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; rotorcraft: helicopter
- Flight time: 22,000 hours in all; 200 in the last 90 days; 40 in the last 30 days; 18,000 as pilot in command
- Medical certificate: Class 2 (valid medical--w/ waivers/lim.)
- Seat: left
The aircraft
- Airframe total time: 7,922 hours
- Last inspection: annual inspection, August 31, 1993; 90 hours since
- Maximum gross weight: 7,200 lb
- Seats: 7
- Landing gear: fixed
- Engine: Lycoming T53-L11-D (turboshaft); 0 hours total
- Operator: Clearwater Management CO. INC.
The flight
- Flight plan: none
- Runway 0
Weather at the time
- Light: daylight
- Sky: clear
- Temperature: 55°F (13°C), dew point 0°F (-18°C)
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.