WPR11CA101
2011-01-15 · Three Forks, Montana, United States · None · 1 aircraft · Status: Completed
Airport 9S5
Current FAA registration · N78BR
- Make / Model
- BELL 206B
- Year of manufacture
- 1988 · 23 years old at event
- Engine
- ROLLS-ROYC 250-C20J (420 hp)
- Seats / Engines
- 5 seats · 1 engine
- Last airworthiness date
- 20060608
- ADS-B equipped
- Yes — Mode-S AA8E56
Source: FAA Aircraft Registry (releasable master file).
Aircraft involved
Probable cause & findings
The pilot’s inadequate use of throttle during the practice autorotation that resulted in a hard landing.
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. 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. Source: NTSB Aviation Accident Database Retrieved: 2026-02-12
NTSB Findings
FAA avdata. C = Cause, F = Factor.
- C Aircraft-Aircraft power plant-Engine controls-Power lever-Incorrect use/operation - C
- C Personnel issues-Task performance-Use of equip/info-Use of equip/system-Pilot - C
Verbatim from NTSB's published report. Source file
NTSB_2011_WPR11CA101.txt.
Findings + structured fields enriched from FAA avall.mdb.
Full investigation docket on
data.ntsb.gov ↗.
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