Thursday, December 23, 2021

Fuel Exhaustion: Enstrom F-28A, N46MU; accident occurred July 28, 2021 in Mountain Home, Elmore County, Idaho

Aviation Accident Final Report - National Transportation Safety Board

The National Transportation Safety Board did not travel to the scene of this accident. 

Additional Participating Entity: 
Federal Aviation Administration / Flight Standards District Office; Boise, Idaho

Location: Mountain Home, Idaho
Accident Number: WPR21LA293
Date and Time: July 28, 2021, 11:30 Local 
Registration: N46MU
Aircraft: Enstrom F-28A 
Aircraft Damage: Substantial
Defining Event: Fuel exhaustion 
Injuries: 1 None
Flight Conducted Under: Part 91: General aviation - Personal


The pilot reported that, while the helicopter was in the hanger, he put 4 gallons of fuel into the left fuel tank. He then intended to hover taxi to the fuel island for fuel. He observed people and an aircraft near the fuel island, and he hover taxied to a dirt area. While about 12-15 ft above ground level, the engine had a complete loss of power. He further reported that he was too low to autorotate, landed hard on uneven terrain and collapsed the left skid. An inspection revealed that both fuel tanks were empty. The helicopter sustained substantial damage to the fuselage and main rotor blades. The pilot reported that there were no preaccident mechanical malfunctions or failures with the helicopter that would have precluded normal operation.

Probable Cause and Findings

The National Transportation Safety Board determines the probable cause(s) of this accident to be:
The pilot's improper fuel planning and improper in-flight decision-making, which resulted in a total loss of engine power due to fuel exhaustion and a subsequent hard landing on uneven terrain. 


Aircraft Fuel - Fluid level
Personnel issues Fuel planning - Pilot
Personnel issues Aircraft control - Pilot
Personnel issues Decision making/judgment - Pilot
Environmental issues Sloped/uneven terrain - Contributed to outcome

Factual Information

History of Flight

Maneuvering-hover Fuel exhaustion (Defining event)
Maneuvering-hover Loss of engine power (total)
Autorotation Hard landing

Pilot Information

Certificate: Private 
Age: 67,Male
Airplane Rating(s): Single-engine land 
Seat Occupied: Left
Other Aircraft Rating(s):
Helicopter Restraint Used: 4-point
Instrument Rating(s): None
Second Pilot Present: No
Instructor Rating(s): None
Toxicology Performed:
Medical Certification: Class 3 With waivers/limitations 
Last FAA Medical Exam: March 11, 2021
Occupational Pilot: No 
Last Flight Review or Equivalent: August 25, 2020
Flight Time: (Estimated) 3100 hours (Total, all aircraft), 5 hours (Total, this make and model), 2885 hours (Pilot In Command, all aircraft)

Aircraft and Owner/Operator Information

Aircraft Make: Enstrom 
Registration: N46MU
Model/Series: F-28A 
Aircraft Category: Helicopter
Year of Manufacture: 1974 
Amateur Built:
Airworthiness Certificate: Normal 
Serial Number: 253
Landing Gear Type: Skid
Seats: 3
Date/Type of Last Inspection: August 23, 2020 Annual
Certified Max Gross Wt.: 2150 lbs
Time Since Last Inspection: 5 Hrs 
Engines: 1 Reciprocating
Airframe Total Time: 3907 Hrs
Engine Manufacturer: Lycoming
ELT: Installed, not activated
Engine Model/Series: HIO-360-C1A
Registered Owner: 
Rated Power: 205
Operating Certificate(s) Held: None

Meteorological Information and Flight Plan

Conditions at Accident Site: Visual (VMC) 
Condition of Light: Day
Observation Facility, Elevation: KMUO,2996 ft msl 
Distance from Accident Site: 8 Nautical Miles
Observation Time: 11:58 Local
Direction from Accident Site: 231°
Lowest Cloud Condition: Few / 15000 ft AGL 
Visibility: 10 miles
Lowest Ceiling: 
Visibility (RVR):
Wind Speed/Gusts: 12 knots / 
Turbulence Type Forecast/Actual: None / None
Wind Direction: 320° 
Turbulence Severity Forecast/Actual: N/A / N/A
Altimeter Setting: 30.14 inches Hg 
Temperature/Dew Point: 31°C / 8°C
Precipitation and Obscuration: No Obscuration; No Precipitation
Departure Point: Mountain Home, ID (U76)
Type of Flight Plan Filed: None
Destination: Mountain Home, ID 
Type of Clearance: None
Departure Time: 11:30 Local 
Type of Airspace: Class G

Airport Information

Airport: Mountain Home Municipal Airport U76
Runway Surface Type:
Airport Elevation: 3166 ft msl
Runway Surface Condition: Dry; Soft
Runway Used: 
IFR Approach: None
Runway Length/Width:
VFR Approach/Landing: None

Wreckage and Impact Information

Crew Injuries: 1 None 
Aircraft Damage: Substantial
Passenger Injuries:
Aircraft Fire: None
Ground Injuries: 
Aircraft Explosion: None
Total Injuries: 1 None 
Latitude, Longitude: 43.131389,-115.7303