Accident Boeing/Aurora Flight Sciences Pegasus N83AU, 04 Jun 2019
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ASN Wikibase Occurrence # 226471
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Time:07:19 LT
Type:Boeing/Aurora Flight Sciences Pegasus
Owner/operator:Aurora Flight Sciences
Registration: N83AU
MSN: AU-083
Fatalities:Fatalities: 0 / Occupants: 0
Aircraft damage: Substantial
Location:Manassas Airport (KHEF) -   United States of America
Phase: Manoeuvring (airshow, firefighting, ag.ops.)
Departure airport:Manassas Regional-Harry P. Davis Field, VA (MNZ/KHEF)
Destination airport:Manassas Regional-Harry P. Davis Field, VA (MNZ/KHEF)
Investigating agency: NTSB
Confidence Rating: Accident investigation report completed and information captured
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.

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.


FAA register:


Accident investigation:
Investigating agency: NTSB
Status: Investigation completed
Download report: Final report


Revision history:

23-Jun-2019 14:11 harro Added
17-Mar-2020 19:14 Aerossurance Updated [Time, Total occupants, Phase, Departure airport, Destination airport, Source, Embed code, Damage, Narrative]
27-Mar-2021 20:30 ASN Update Bot Updated [Other fatalities, Source, Damage, Narrative, Plane category, Category, Accident report]

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