Probable cause
A failure of the drive belt for reasons that could not be determined based on the available information.
NTSB analysis
As the helicopter approached the airport, the pilot reported that the helicopter's engine rpm increased, and the rotor rpm decayed. He conducted an autorotation to the field. An examination of the helicopter revealed that the helicopter's main rotor drive belt/cog belt lost teeth resulting in a failure of the belt to drive the main rotor blades. The drive belt had recently been installed, about 3.5 hours prior to the accident. The circumstances of the accident are consistent with improper tension of the cog belt resulting in a failure of the belt.
Text from the NTSB. Open the NTSB docket for CEN17LA365 for the full record.
Event
- Date
- Sep 16, 2017
- Type
- Accident
- Place
- Plymouth, Indiana
- Highest injury
- None
- Weather
- Visual (VMC)
- Light
- Day
Amateur-built EXEC 162 F
- N-number
- N123XZ
- Category
- Helicopter
- Year built
- 1998
- 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.