- Date
- March 13, 2015, 18:00 local (Mar 14, 2015, 00:00 UTC)
- Place
- Shelby, MT
- Injuries
- 2 uninjured
- Damage
- Substantial damage
- Phase of flight
- Maneuvering
- Aircraft
- N5688NEnstrom F28 - C
- Defining event
- Maneuvering-low-alt flying: Low altitude operation/event
- Weather
- Visual (VMC) · Day
- Status
- Completed · report April 21, 2015
- Report
- Approved by Office Director
- NTSB office
- Western Pacific Region
- Parties
- Federal Aviation Administration
- FAA report
- 20150313002269A
- Case key
- 90888
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 failure to maintain main rotor RPM during a low altitude operation, which resulted in a loss of aircraft control and collision with terrain.
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 reported that while maneuvering at a low altitude over a machinery yard, he observed a low rotor rpm condition. When he lifted the collective the rpm continued to bleed off, which resulted in the helicopter yawing to the left. The pilot stated that he managed to get the helicopter back under control, but then entered the low rotor rpm condition a second time. Unable to keep the helicopter flying straight, the aircraft impacted up sloping terrain with its left skid, followed by the main rotor blades striking the ground. The helicopter sustained substantial damage due to the impact with terrain. The pilot reported no preimpact mechanical malfunctions or failures with the helicopter that would have precluded normal operation.
Factual narrative
The pilot reported that while maneuvering at a low altitude over a machinery yard, he observed a low rotor rpm condition. When he lifted the collective the rpm continued to bleed off, which resulted in the helicopter yawing to the left. The pilot stated that he managed to get the helicopter back under control, but then entered the low rotor rpm condition a second time. Unable to keep the helicopter flying straight, the aircraft impacted up sloping terrain with its left skid, which was followed by the main rotor blades striking the ground. The helicopter sustained substantial damage due to the impact with terrain. The pilot reported no preimpact mechanical malfunctions or failures with the helicopter that would have precluded normal operation.
Aircraft
- Registration
- N5688N
- Reported as
- Enstrom F28 - C
- Category
- Helicopter
- Serial number
- 495-2
- Built
- 1980
- Engine
- Lycoming HIO-360, reciprocating
- Damage
- Substantial damage
- Flight
- Personal · Part 91
- Airworthiness certificate
- Standard, Normal
- Last inspection
- Annual · April 20, 2014 · 1,378 hours before
- Departed
- SBX · Shelby, MT
- Destination
- SBX · Shelby, MT
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
- 53
- Injuries
- None
- Certificate
- Private
- Airplane ratings
- Single-engine land
- Medical
- Class 3, With waivers/limitations
- Last flight review
- February 17, 2013
- Seat
- Left
- Restraint
- Lap only
- Flight hours
- 168 total · 112 in this make and model
Weather
- Conditions
- Visual (VMC) · Day
- Wind
- 200° at 7 knots
- Visibility
- 10 statute miles
- Lowest ceiling
- None
- Temperature
- 64 °F, dew point 48 °F
- Altimeter
- 30.15 inHg
- Observed at
- CTB, 10 nm away
Docket · 1
The files NTSB released with the investigation on April 16, 2015, on NTSB’s docket system: statements, records, photos and specialists’ reports. 3.1 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.
Other investigations on N5688N · 1
Matched to the same aircraft by N-number and date.