Hiller UH-12E accident near Thermal, California, May 18, 1983
On May 18, 1983 at about 6:00 pm local time, a Hiller UH-12E (helicopter), registered N4027L, was substantially damaged in an accident near Thermal, 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 NTSB has not yet published a probable cause for this accident. Investigations usually take one to two years; this page updates when the final report is released.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- May 18, 1983 · about 6:00 pm local time
- Place
- Thermal, 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
- N4027L · registry record · serial 5074
- Damage
- Substantial damage
- Flight
- Aerial application (crop spraying) flight · agricultural flying rules (Part 137)
The NTSB's narrative final · quoted from the NTSB record
THE PLT REPORTED THAT HE WAS APRX 1/3 OF THE WAY THRU A PROCEDURE TURN AT ABOUT 60 FT AGL, WHEN HE EXPERIENCED A PARTIAL POWER LOSS. HE COMPLETED THE TURN, LEVELED THE HELICOPTER & MOUMENTARILY REGAINED COMPLETE POWER, THEN THE ENGINE QUIT OPERATING. AN AUTOROTATIVE LANDING TO A ROAD WAS STARTED, BUT THE PLT SAW A TRUCK APPROACHING, SO HE MANEUVERED BACK TOWARD THE FIELD THAT HE HAD BEEN SPRAYING. DURING THE LANDING FLARE, THE TAIL ROTOR STRUCK THE GROUND. SUBSEQUENTLY, THE PLT LOST CONTROL OF THE HELICOPTER & IT CAME TO REST ON ITS RIGHT SIDE. DURING AN INVESTIGATION, THE AUXILIARY FUEL PUMP HAD TO BE PRIMED BEFORE THE ENG WOULD START. REPORTEDLY, A FUEL INTERUPTION TO THE PUMP COULD CAUSE IT TO LOSE ITS PRIME, & IF THIS OCCURRED DURING FLT, FUEL STARVATION WOULD OCCUR. THE PLT STATED THAT HE HAD MADE CYCLIC TURNS TO KEEP POSTITIVE G'S ON THE ROTOR SYSTEM RATHER THAN CYCLIC & PEDAL TURNS. APRX GAL OF FUEL WAS REMAINING.
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, flight instructor, commercial pilot
- Ratings: multi-engine land; single-engine land; instructor: helicopter; instrument: airplane; rotorcraft: helicopter
- Flight time: 8,050 hours in all; 4,800 in this make and model; 183 in the last 90 days; 7,790 as pilot in command; 300 on instruments
- Medical certificate: Class 2 (valid medical--no waivers/lim.)
- Seat: ctr
The aircraft
- Airframe total time: 951 hours
- Last inspection: annual inspection, December 20, 1982; 74 hours since
- Maximum gross weight: 2,750 lb
- Seats: 3
- Landing gear: retractable
- Engine: Lycoming VO540-C2A (piston); 0 hours total
The flight
- Flight plan: none
- Runway 0
Weather at the time
- Light: daylight
- Wind: from 240° at 5 knots
- Visibility: 50 statute miles
- Sky: clear
- Temperature: 91°F (33°C), dew point 0°F (-18°C)
- Altimeter: 29.00 inHg
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 N4027L 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.