Probable cause
A loss of engine power due to fuel starvation as a result of blocked fuel vents.
NTSB analysis
The pilot topped off the fuel tanks prior to takeoff. Approximately two hours later, a loss of engine power was experienced. The pilot performed an autorotation to a field; however, the tail rotor contacted a 4x4 wooden post during the landing. This resulted in substantial damage to the tail boom. Inspection of the helicopter revealed the left fuel tank was empty and the right fuel tank was full. Inspection of the fuel system revealed the right tank fuel vent was completely blocked by mud dauber debris along with the remains of two mud daubers. The left fuel tank vent was partially blocked by mud dauber debris. Both tanks feed to a central line which provides fuel to the engine. In addition, the nut on the T-fitting from the left tank fuel line was found finger tight.
Text from the NTSB. Open the NTSB docket for CEN09CA517 for the full record.
Event
- Date
- Aug 11, 2009
- Type
- Accident
- Place
- Covert, Michigan
- Highest injury
- None
- Weather
- Visual (VMC)
- Light
- Day
Bell 47G-2A
- N-number
- N9526
- Category
- Helicopter
- Damage
- Substantial
- Operating rule
- Part 91 (general aviation)
- Purpose of flight
- Personal
Other records under this N-number
From the NTSB aviation accident database: N-registered aircraft, events since 2008, data through Oct 28, 2026. The file is published monthly, so the latest weeks are incomplete and recent records can change. The official source is the NTSB aviation investigation search. CheckAero is independent and not affiliated with the NTSB.