AURORA PAV near Manassas, VA — 2019-06-04

Final reportDCA19LA154

Date: 2019-06-04
Location: Manassas, VA, USA
Airport: KHEF
Aircraft: AURORA PAV
Registration: N83AU
Category: Helicopter
Fatalities: 0
Phase of flight: Landing

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 narrative

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.

Analysis

Primary failure mode: Automation / mode confusion
First missed decision gate: Terminate flight before entering autoland due to data dropouts.

NTSB coding

Flight control sys malf/fail · Uncontrolled descent

Evidence available

3 docket documents

View NTSB final report View NTSB docket

Docket documents3

Party Formform
Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1form
Report from Partyreport

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