- Date
- June 6, 1991, 20:45 local (Jun 7, 1991, 03:45 UTC)
- Place
- Huron, CA
- Injuries
- 1 uninjured
- Damage
- Substantial damage
- Phase of flight
- Enroute
- Aircraft
- N507HAHiller UH-12E
- Weather
- Visual (VMC) · Night/bright
- Status
- Completed · report May 27, 1993
- Report
- Approved by Office Director
- FAA report
- 19910606020509A
- Case key
- 27237
From the NTSB’s public API. By law, NTSB reports can’t be used as evidence in lawsuits over the accident.
On this page
Probable cause
That unknown pilot(s) impoperly used the throttle control which caused an overspeed condition. Contributing to this accident was the connecting rod bolt fatigue failure.
Sequence of events
NTSB’s coding before 2008: each occurrence and phase of flight, and the causes and factors under it. The codes are defined in NTSB’s coding manual.
Analysis
The pilot completed an aerial application flight and was returning to the loading area when the helicopter sustained a total loss of power. During the subsequent autorotation the pilot attempted to sideslip the helicopter between the almond trees but was unable to do so. The engine and subsequent metallurgical examination disclosed the no. 3 cylinder connecting rod bolt failed due to fatigue. Company maintenance personnel reported that the fatigue was caused by consistent engine overspeed power settings by the pilots flying the helicopter.
Aircraft
- Registration
- N507HA
- Reported as
- Hiller UH-12E
- Category
- Helicopter
- Serial number
- 5007
- Airframe hours
- 3,112
- Engine
- Lycoming VO-540-C2A, 305 horsepower, reciprocating
- Damage
- Substantial damage
- Flight
- Aerial application · Part 137
- Operator
- San Joaquin Helicopters
- Registered owner
- San Joaquin Helicopters
- Airworthiness certificate
- Standard, Normal
- Last inspection
- Annual · February 25, 1991 · 114 hours before
Matched to the registry by N-number and the event date; the registry’s history has gaps, so older matches can be wrong. Compare the reported make and model.
Flight crew
As NTSB recorded them. NTSB leaves out names.
- Role
- Pilot
- Age
- 43
- Certificate
- Commercial
- Airplane ratings
- Multi-engine land, Single-engine land
- Medical
- Class 2, Valid Medical--no waivers/lim.
- Seat
- Center
- Flight hours
- 15,000 total · 15,000 as pilot in command
Weather
- Conditions
- Visual (VMC) · Night/bright
- Visibility
- 20 statute miles
- Lowest ceiling
- None
- Temperature
- 70 °F
FAA reports on this event · 1
The FAA’s own accident and incident reports, matched to the aircraft by N-number and date.