Hiller UH-12E accident near Chowchilla, California, February 3, 1995
On February 3, 1995 at about 7:15 pm local time, a Hiller UH-12E (helicopter), registered N9293Z, was destroyed in an accident near Chowchilla, 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 in-flight failure and separation of the main rotor hub due to a fatigue crack.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- February 3, 1995 · about 7:15 pm local time
- Place
- Chowchilla, 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
- N9293Z · no longer on the register · serial 1548
- Damage
- Destroyed
- Flight
- Aerial application (crop spraying) flight · agricultural flying rules (Part 137)
The NTSB's narrative final · quoted from the NTSB record
THE PILOT WAS APPLYING CHEMICALS TO A FIELD AT A SLOW AIRSPEED ABOUT 10 FEET OFF THE GROUND. A SEVERE VIBRATION STARTED THROUGH THE AIRFRAME, AND THE PILOT DECIDED TO LAND IMMEDIATELY. THE PILOT WAS TURNING TO A LANDING AREA WHEN THE VIBRATION SUDDENLY CEASED, THE HELICOPTER FELL TO THE GROUND ON ITS NOSE, AND ROLLED OVER ONTO ITS TOP. ONE MAIN ROTOR BLADE AND HALF THE HUB WERE FOUND MORE THAN 100 YARDS FROM THE HELICOPTER. THE SECOND BLADE WAS FOUND ATTACHED TO THE REMAINDER OF THE HUB, ABOUT 150 FEET FROM THE WRECKAGE. THE TWO PIECES OF THE FRACTURED AND SEPARATED MAIN ROTOR HUB WERE RECOVERED AND METALLURGICALLY EXAMINED. THE HUB SEPARATED DUE TO A FRACTURE THROUGH ITS CENTER. THE EXAMINATIONS DISCLOSED THAT THE FRACTURE THROUGH THE HUB CENTER STEMMED FROM FATIGUE CRACKS WHICH INITIATED FROM THE TENSION-TORSION PIN HOLE ON THE LEADING EDGE SIDE OF ONE HUB ARM. THE ORIGIN POINT OF THE FATIGUE CRACK WAS DETERMINED TO BE INSIDE THE TT PIN HOLE AND EXHIBITED CORROSION DEPOSITS TYPICALLY SEEN IN ALUMINUM ALLOYS. THE CRACK WOULD NOT HAVE BEEN VISIBLE DURING AN EXTERNAL INSPECTION. THE FATIGUE CRACK AND FRACTURE ARE IN AREAS NOT COVERED BY THE RECURRING INSPECTION REQUIREMENTS OF AD 73-20-03.
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: multi-engine land; single-engine land; single-engine sea; instrument: airplane; rotorcraft: helicopter
- Flight time: 12,000 hours in all
- Medical certificate: Class 2 (valid medical--w/ waivers/lim.)
- Seat: ctr
The aircraft
- Airframe total time: 3,028 hours
- Last inspection: 100-hour inspection, January 10, 1995; 78 hours since
- Maximum gross weight: 2,750 lb
- Seats: 3
- Landing gear: fixed
- Engine: Lycoming VO-540 (piston); 0 hours total
The flight
- Departed from: 206 at 6:45 pm
- Flight plan: none
- Runway 0
Weather at the time
- Light: not reported
- Visibility: 3 statute miles
- Sky: overcast at 800 ft; not recorded
- Temperature: 54°F (12°C), dew point 48°F (9°C)
- Altimeter: 30.00 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.
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.