Texas Helicopter M47A WASP accident near Stockton, California, August 27, 1990
On August 27, 1990 at about 7:10 am local time, a Texas Helicopter M47A WASP, registered N43921, was substantially damaged in an accident near Stockton, 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 PILOT MISJUDGED THE ALTITUDE DURING THE FLARE/TOUCHDOWN PHASE OF THE AUTOROTATION. FACTORS RELATING TO THIS ACCIDENT ARE FAILURE OF THE RIGHT MAGNETO.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- August 27, 1990 · about 7:10 am local time
- Place
- Stockton, California · map
- Type
- Accident
- Injuries
- No one was hurt; 1 person was on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Texas Helicopter M47A WASP
- Registration
- N43921 · registry record · serial 76-003
- 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 LANDED THE HELICOPTER AND IT WAS RELOADED WITH CHEMICALS FOR ANOTHER AGRICULTURAL SPRAYING FLIGHT. SHORTLY AFTER DEPARTING THE LOAD SITE, THE PILOT HEARD A LOUD SOUND ENAMATE FROM THE ENGINE AREA FOLLOWED BY A SUDDEN LOSS OF POWER AND VIBRATION. THE PILOT IMMEDIATELY EXECUTED AN AUTOROTATION TO THE OPEN AREA, BUT MISJUDGED THE FLARE ALTITUDE AND EXPERIENCED A HARD LANDING WHICH CAUSED SUBSTANTIAL DAMAGE TO THE HELICOPTER. THE INVESTIGATION REVEALED THAT THE RIGHT MAGNETO CONTACT POINTS 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: 2,500 hours in all; 600 in this make and model; 200 in the last 90 days; 95 in the last 30 days; 2,200 as pilot in command
- Medical certificate: Class 2 (valid medical--w/ waivers/lim.)
- Seat: ctr
The aircraft
- Airframe total time: 2,311 hours
- Last inspection: 100-hour inspection, August 2, 1990; 48 hours since
- Maximum gross weight: 2,450 lb
- Seats: 1
- Landing gear: fixed
- Engine: Lycoming VO-435-A1F (piston); 0 hours total
The flight
- Flight plan: none
- Runway 0
Weather at the time
- Light: daylight
- Wind: from 360° at 5 knots
- Visibility: 40 statute miles
- Sky: clear
- Temperature: 70°F (21°C), dew point 54°F (12°C)
- Altimeter: 30.00 inHg
- Observation at 3:51 pm from SCK, 10 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.
Other NTSB records under N43921 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.