- Date
- January 15, 2011, 13:00 local (20:00 UTC)
- Place
- Three Forks, MT
- Injuries
- 2 uninjured
- Damage
- Substantial damage
- Phase of flight
- Emergency descent
- Aircraft
- N78BRBell 206B3
- Defining event
- Autorotation: Hard landing
- Weather
- Visual (VMC) · Day
- Status
- Completed · report May 26, 2011
- Report
- Approved by Office Director
- NTSB office
- Western Pacific Region
- Parties
- FAA FSDO
- FAA report
- 20110115001329A
- Case key
- 78171
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 pilot’s inadequate use of throttle during the practice autorotation that resulted in a hard landing.
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
The pilot practiced several maneuvers and then entered a straight-in practice autorotation. He pointed the helicopter into the wind at 800 feet above ground level near midfield and above the runway. He reduced the throttle to flight idle and lowered the collective while gently flaring the nose of the helicopter to set up the appropriate main rotor rpm and airspeed. He reported that he monitored those parameters carefully during the descent and noted that they remained well within the normal range. At the bottom of the descent, the pilot flared a little high to allow a margin of safety for tail boom clearance as he was planning a power recovery from the autorotation. The pilot stated that he did not add power at that point and that there was inadequate rotor inertia to dampen the landing, even though he applied full collective deflection. The helicopter hit hard and sustained substantial damage. The aft portion of the tail boom and tail rotor separated due to a main rotor blade contact and the skids were damaged.
Factual narrative
The pilot practiced several maneuvers, and then entered a straight-in practice autorotation. He pointed the helicopter into the wind at 800 feet above ground level (agl) near midfield and above the runway. He rolled the throttle to flight idle, and lowered the collective while gently flaring the nose of the helicopter to set up the appropriate main rotor revolutions per minute (rpm) and airspeed. He monitored those parameters carefully during the descent, and noted that they remained well within the normal range. At the bottom of the descent, the pilot flared a little high to allow a margin of safety for tail boom clearance as he was planning a power recovery from the autorotation. However, the pilot stated that he did not add power at that point, and there was inadequate rotor inertia to dampen the landing, even though he applied full collective deflection. The helicopter hit hard, and sustained substantial damage. The aft portion of the tail boom and tail rotor separated due to a main rotor blade contact, and the skids were damaged. The pilot performed an emergency shut down; he closed the throttle, and switched off the battery, generator, and fuel valve. After exiting the helicopter he secured the battery.
Aircraft
- Registration
- N78BR
- Reported as
- Bell 206B3
- Category
- Helicopter
- Serial number
- 4001
- Airframe hours
- 2,701
- Engine
- Rolls-Royce Allison 250-C20J, 420 horsepower, turbo shaft
- Damage
- Substantial damage
- Flight
- Personal · Part 91
- Operator
- Skymission LLC
- Registered owner
- Skymission LLC
- Airworthiness certificate
- Standard, Normal
- Last inspection
- Annual · June 23, 2010
- Departed
- BZN · Bozeman, MT
- Destination
- BZN · Bozeman, MT
- Airport
- 9S5 · Three Forks, runway 02, 5,100 × 60 ft, asphalt
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
- 57
- Injuries
- None
- Certificate
- Private
- Medical
- Class 3, With waivers/limitations
- Last flight review
- April 11, 2009
- Seat
- Right
- Flight hours
- 692 total · 674 in this make and model · 607 as pilot in command · 26 in the last 90 days · 4 in the last 30 days
Weather
- Conditions
- Visual (VMC) · Day
- Wind
- 310° at 4 knots
- Visibility
- 10 statute miles
- Lowest ceiling
- None
- Temperature
- 41 °F, dew point 27 °F
- Altimeter
- 30.11 inHg
- Observed at
- KBZN
Docket · 1
The files NTSB released with the investigation on February 17, 2011, on NTSB’s docket system: statements, records, photos and specialists’ reports. 2.8 MB 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.