Probable cause
a loss of hover lift thrust provided by the eight lift motors due to a false on-ground rotor speed reduction command, resulting from excessive vibration.
NTSB analysis
The aircraft experienced a vibrational excitation environment which exceeded the previously measured accelerations used to establish an autopilot ground-sensing threshold. The excessive oscillations activated the ground-sensing system, which transitioned the autopilot from Autoland into "ground" mode and commanded a reduction in rotor speed.
Text from the NTSB. Open the NTSB docket for DCA19LA154 for the full record.
Event
- Date
- Jun 4, 2019
- Type
- Accident
- Place
- Manassas, Virginia
- Nearest airport
- Manassas (KHEF)
- Weather
- Visual (VMC)
- Light
- Day
PAV
- N-number
- N83AU
- Category
- Helicopter
- Damage
- Substantial
- Operating rule
- Part 91 (general aviation)
- Purpose of flight
- Flight test
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.