- Date
- August 24, 1991, 19:50 local (Aug 25, 1991, 02:50 UTC)
- Place
- Sparks, NV
- Injuries
- 1 uninjured
- Damage
- Substantial damage
- Phase of flight
- Enroute
- Aircraft
- N100HHHiller UH12D
- Weather
- Visual (VMC) · Dusk
- Status
- Completed · report April 8, 1993
- Report
- Approved by Office Director
- FAA report
- 19910824036649A
- Case key
- 27337
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
The encounter with rough, unsuitable terrain during a precautionary landing. Contributing to the accident was the pilot's decision to make an autorotation after encountering an airframe vibration.
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 certificated private helicopter pilot, the sole occupant, was on a local area flight when a strong, medium to high frequency vibration developed in the tail section of his helicopter. The pilot elected to make a precautionary landing in an open dirt area, and executed an autorotation. After touchdown the helicopter slid on rough, rocky terrain, causing the main rotor blades to contact the tail boom. Three feet of the tail boom including the tail rotor gear box and blades, and the tail rotor drive shaft were severed. An examination of the tail rotor drive shaft at the position where a support bearing is mounted, revealed signs of heat and wear. During the impact sequence, the drive shaft support bearing departed the helicopter and was not recovered.
Aircraft
- Registration
- N100HH
- Reported as
- Hiller UH12D
- Category
- Helicopter
- Serial number
- 1266
- Airframe hours
- 5,868
- Engine
- Lycoming VO-435-AIC, 250 horsepower, reciprocating
- Damage
- Substantial damage
- Flight
- Personal · Part 91
- Operator
- Pathfinder Technology Inc., doing business as Richard Swartzendruber
- Registered owner
- Pathfinder Technology Inc.
- Airworthiness certificate
- Standard, Normal
- Last inspection
- Annual · March 12, 1991 · 10 hours before
- Departed
- NONE · Reno, NV
- Destination
- 45D · Stead, NV
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
- 50
- Certificate
- Private
- Medical
- Class 2, Valid Medical--no waivers/lim.
- Seat
- Center
- Flight hours
- 265 total · 265 as pilot in command · 5 in the last 90 days · 2 in the last 30 days · 1 in the last 24 hours
Weather
- Conditions
- Visual (VMC) · Dusk
- Wind
- 270° at 5 knots
- Visibility
- 10 statute miles
- Lowest ceiling
- None
- Temperature
- 81 °F
FAA reports on this event · 1
The FAA’s own accident and incident reports, matched to the aircraft by N-number and date.