Pilot Debrief

BELL HELICOPTER TEXTRON INC APT70 near Mineral Wells, TX — 2023-03-14

Final reportCEN23LA135
Sign in to save
Date
2023-03-14
Location
Mineral Wells, TX, USA
Aircraft
BELL HELICOPTER TEXTRON INC APT70
Registration
N314AL
Category
PLFT
Highest injury
None
Fatalities
0
Phase of flight
Hover

Probable cause

The flight crew’s loss of control of the unmanned aircraft due to software limitations. Contributing to the accident was the overly restrictive low voltage threshold limits.

Contributing factors

Contributing to the accident was the overly restrictive low voltage threshold limits.

NTSB narrative

During a flight test, the unmanned aircraft’s flight control computer registered a low battery voltage reading and entered an automatic land in place flight maneuver. The aircraft was hovering over a large bush at the time and the ground station operator (GSO) attempted to override the system, but the system rejected the commands. The GSO attempted to change the land in place waypoint, but the system again rejected the command. The aircraft performed its land in place maneuver and collided with the bush, which resulted in the aircraft tipping over and coming to rest inverted. The operator reviewed the aircraft systems and found the low voltage threshold to be overly restrictive. In addition, software prevented the flight crew from overriding the land in place command and regaining control of the aircraft by changing the waypoint.

Analysis

Primary failure mode
Mechanical failure
First missed decision gate
Crew could have addressed low battery issue before transition to hover.

NTSB coding

Evidence available

  • Photos
  • 5 docket documents
View NTSB final reportView NTSB docket

Docket documents5

Related mishaps