Hiller UH-12E accident near Lemoore, California, January 24, 1999
On January 24, 1999 at about 5:00 pm local time, a Hiller UH-12E (helicopter), registered N67064, was substantially damaged in an accident near Lemoore, California. 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
The inadequate nature of the operator's maintenance, which failed to detect the primer and magneto discrepancies. An overly lean fuel mixture and/or magneto cross firing resulted in detonation, an ensuing connecting rod failure, and a total loss of engine power. Contributing factors were the helicopter's low altitude and the uneven, soft nature of the terrain.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- January 24, 1999 · about 5:00 pm local time
- Place
- Lemoore, California · map
- Type
- Accident
- Injuries
- No one was hurt; 1 person was on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Hiller UH-12E · all UH-12Es on the register
- Registration
- N67064 · no longer on the register · serial 1355
- Damage
- Substantial damage
- Flight
- Aerial application (crop spraying) flight · agricultural flying rules (Part 137)
The NTSB's narrative final · quoted from the NTSB record
While maneuvering during an aerial application flight at 15 feet above an alfalfa field, the pilot heard a noise emanating from the engine, and it seized. The pilot made a forced landing in the underlying soft field, and the helicopter rolled over after touching down on the uneven terrain. Maintenance records review disclosed that the helicopter's engine had operated about 482 hours since being overhauled. The engine examination revealed that the number two connecting rod was broken at its crankshaft end. Additionally, an inspection of the associated cylinder and piston revealed evidence of detonation. Similar excessive heat exposure signatures were observed with the other five piston heads. A small hole was found chaffed into the fuel primer line. Carbon deposits and burned rotor fingers were found in both magnetos.
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: 8,109 hours in all; 3,121 in this make and model; 29 in the last 90 days; 11 in the last 30 days; 7,900 as pilot in command
- Medical certificate: Class 2 (valid medical--no waivers/lim.)
- Seat: ctr
The aircraft
- Airframe total time: 8,029 hours
- Last inspection: 100-hour inspection, July 3, 1998; 96 hours since
- Maximum gross weight: 2,750 lb
- Seats: 1
- Landing gear: fixed
- Engine: Lycoming VO-540-C2A (piston); 0 hours total
The flight
- Flight plan: none
- Runway 0
Weather at the time
- Light: daylight
- Wind: from 315° at 4 knots, gusting 6
- Visibility: 5 statute miles
- Sky: scat at 4,000 ft
- 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.