Hiller UH-12E accident near Auburn, Washington, August 23, 1993
On August 23, 1993, a Hiller UH-12E (helicopter), registered N9785C, was substantially damaged in an accident near Auburn, Washington (Auburn airport). It was a flight of an unrecorded kind under general aviation rules (Part 91). No one was hurt; 3 people were on board or involved. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
FAILURE OF THE CONNECTING ROD BOLT. THE HIGH VEGETATION WAS A FACTOR.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- August 23, 1993
- Place
- Auburn, Washington · Auburn · map
- Type
- Accident
- Injuries
- No one was hurt; 3 people were on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Hiller UH-12E · all UH-12Es on the register
- Registration
- N9785C · registry record · serial 2269
- Damage
- Substantial damage
- Flight
- Flight of an unrecorded kind · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
DURING A SIGHTSEEING FLIGHT, THE PILOT HEARD A SERIES OF POPS AND THE WARNING LIGHTS FOR THE OIL PRESSURE AND TEMPERATURE ILLUMINATED. THE PILOT INITIATED AN AUTOROTATION TO AN OPEN FIELD. DURING THE LANDING MANEUVER, THE TAIL ROTOR WAS SEPARATED. AN ENGINE INSPECTION REVEALED THAT THE NUMBER 4 CONNECTING ROD SHANK WAS BROKEN INTO THREE PIECES. A METALLURGICAL EXAMINATION OF THE CONNECTING ROD ASSEMBLY REVEALED THAT THE CONNECTING ROD BOLT DISPLAYED A FRACTURE TYPICAL OF A TENSILE OVERSTRESS SEPARATION. THE OTHER CONNECTING ROD BOLT WAS NOT LOCATED.
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, military
- Ratings: multi-engine land; instrument: airplane; instrument: helicopter; rotorcraft: helicopter
- Flight time: 1,892 hours in all; 31 in this make and model; 31 in the last 90 days; 19 in the last 30 days; 1,154 as pilot in command
- Medical certificate: Class 2 (valid medical--no waivers/lim.)
- Seat: ctr
The aircraft
- Airframe total time: 7,181 hours
- Last inspection: continuous airworthiness programme, July 18, 1993; 58 hours since
- Maximum gross weight: 3,100 lb
- Seats: 3
- Landing gear: fixed
- Engine: Lycoming VO-540-C2A (piston); 0 hours total
- Operator: Mayse International
The flight
- Flight plan: none
- Runway 0
Weather at the time
- Light: daylight
- Wind: from 180° at 3 knots
- Visibility: 50 statute miles
- Sky: overcast at 10,000 ft; not recorded at 10,000 ft
- Temperature: 73°F (23°C), dew point 0°F (-18°C)
- Observation at 5:00 pm
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 1 | |||
| Passengers | 2 |
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 N9785C 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.