- Date
- October 30, 2008, 08:40 local (14:40 UTC)
- Place
- Powder River, WY
- Injuries
- 1 minor, 1 uninjured
- Damage
- Substantial damage
- Phase of flight
- Maneuvering
- Aircraft
- N61436Hiller UH-12E
- Defining event
- Maneuvering-low-alt flying: Flight control sys malf/fail
- Weather
- Visual (VMC) · Day
- Status
- Completed · report September 30, 2009
- Report
- Approved by Office Director
- NTSB office
- Western Pacific Region
- Parties
- Federal Aviation Administration
- FAA report
- 20081030851229A
- Case key
- 69377
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
A flight control system malfunction while the helicopter was maneuvering at low altitude due to the failure/separation of the rotor blade control tube.
Findings · 2
NTSB’s coded findings. Those marked are part of the probable cause; the rest are factors or other findings. Under each, the cases with the same finding.
Sequence of events
The events NTSB coded, in order, by phase of flight. The defining event is the one that best describes the accident. Under each, the cases with the same event anywhere in their sequence.
Analysis
While maneuvering about 50 feet above ground level during an aerial observation flight, one blade associated with the control rotor assembly separated from the helicopter, and a violent vibration started. Unable to maintain control, the pilot made a forced landing on the underlying sloping terrain, and the helicopter rolled over. During the subsequent inspection of the rotor system, one of the two control rotor blade assemblies was found separated from the rotor head. A rotor blade control tube had cracked and broken off outboard of the two attachment bolts. The component had been operated 21 hours since receiving its last inspection. The reason for the cracking and separation of the control tube could not be determined.
Factual narrative
October 30, 2008, about 0840 mountain daylight time, a Hiller UH-12E, N61436, experienced a flight control system malfunction while maneuvering about 5 miles west-southwest of Powder River, Wyoming. Unable to maintain control of the helicopter, the pilot made a hard forced landing on the slope of a hillside. Upon touchdown, the helicopter rolled over and was substantially damaged. The commercial certificated pilot received a minor injury, and the passenger was not injured. The helicopter was owned and operated by Wyoming Air Corporation, Casper, Wyoming. Visual meteorological conditions prevailed at the time of the aerial observation (predator control) flight, and no flight plan was filed. The flight was performed under the provisions of 14 Code of Federal Regulations Part 91, and it originated from a refueling vehicle near Powder River, about 0830. The pilot reported to the National Transportation Safety Board investigator that the accident occurred while he was maneuvering about 50 feet above ground level and looking for coyotes. Suddenly, one blade associated with the control rotor assembly separated from the helicopter and a violent vibration started. The pilot reported that the vibration precluded him from being able to read the airspeed indicator, and he only had "minimal control" of the helicopter. During the subsequent examination of the helicopter, one of the two control rotor blade assemblies (Hiller part number 36209-3) was found separated from the rotor head. The rotor control blade assembly tube was observed cracked and broken off outboard of the two bolts attaching it to the cuff assembly. The helicopter had been operated about 21 hours since receiving its last annual inspection.
Aircraft
- Registration
- N61436
- Reported as
- Hiller UH-12E
- Category
- Helicopter
- Serial number
- 5017
- Airframe hours
- 4,115
- Engine
- Lycoming VO-540 SER, 305 horsepower, reciprocating
- Damage
- Substantial damage
- Flight
- Aerial observation · Part 91
- Operator
- Wyoming Air Corp
- Registered owner
- Wyoming Air Corp
- Airworthiness certificate
- Special, Restricted (Special)
- Last inspection
- Annual · September 20, 2008 · 21 hours before
- Departed
- Powder River, WY
- Destination
- Powder River, WY
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
- 33
- Injuries
- Minor
- Certificates
- Flight instructor, Commercial
- Airplane ratings
- Single-engine land
- Instrument ratings
- Airplane
- Medical
- Class 2, Without waivers/limitations
- Last flight review
- August 23, 2007
- Seat
- Left
- Flight hours
- 1,908 total · 448 in this make and model · 1,778 as pilot in command · 39 in the last 90 days · 33 in the last 30 days · 2 in the last 24 hours
Weather
- Conditions
- Visual (VMC) · Day
- Wind
- 200° at 10 knots
- Visibility
- 10 statute miles
- Lowest ceiling
- None
- Temperature
- 61 °F
Docket · 1
The files NTSB released with the investigation on August 10, 2009, on NTSB’s docket system: statements, records, photos and specialists’ reports. 750 KB in all.
FAA reports on this event · 1
The FAA’s own accident and incident reports, matched to the aircraft by N-number and date.