Sikorsky H-19/S55 accident near Richvale, California, March 19, 1991
On March 19, 1991, a Sikorsky H-19/S55 (helicopter), registered N9894, was substantially damaged in an accident near Richvale, 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 FAILURE OF THE ENGINE'S NUMBER 4 CYLINDER INTAKE VALVE KEEPER. TREES UNDER THE HELICOPTER AT THE TIME OF THE LOSS OF ENGINE POWER WERE FACTORS IN THE ACCIDENT.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- March 19, 1991
- Place
- Richvale, California · map
- Type
- Accident
- Injuries
- No one was hurt; 1 person was on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Sikorsky H-19/S55
- Registration
- N9894 · registry record · serial 55998
- 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 PILOT STATED THAT HE WAS DISPENSING HIS 20TH LOAD OF INSECT SPRAY OVER ALMOND TREES. DURING A SWATH RUN THE ENGINE LOST POWER AND THE HELICOPTER IMPACTED THE TREES AND THEN THE GROUND. THE ENGINE'S NUMBER 4 CYLINDER INTAKE VALVE KEEPER FAILED.
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: 1,756 hours in all; 1,276 in this make and model; 141 in the last 90 days; 118 in the last 30 days; 1,445 as pilot in command
- Medical certificate: Class 2 (valid medical--no waivers/lim.)
- Seat: unk
The aircraft
- Last inspection: inspection type not recorded, January 2, 2000
- Maximum gross weight: 7,500 lb
- Seats: 1
- Landing gear: fixed
- Engine: Wright R-1300 (piston); 0 hours total
- Operator: Avag, INC.
The flight
- Flight plan: none
- Runway 0
Weather at the time
- Light: daylight
- Wind: from 220° at 5 knots
- Visibility: 40 statute miles
- Sky: overcast at 20,000 ft; scat at 3,000 ft
- Temperature: 0°F (-18°C), dew point 0°F (-18°C)
- Observation at 11:46 pm from CNO, 19 miles away
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.