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NTSB Final Report: Beeville, TX

 

Location:

Beeville, TX

Accident Number:

DCA19CA170

Date & Time:

06/21/2019, 0842 CDT

Registration:

N243XT

Aircraft:

BOEING CV2

Aircraft Damage:

Substantial

Defining Event:

Nav system malfunction/failure

Injuries:

N/A

Flight Conducted Under:

Part 91: General Aviation - Flight Test


Analysis

On June 21, 2019, at 0842 central daylight time (CDT), N243XT a Boeing CV2-Cargo Air Vehicle (CAV), unmanned aircraft system (UAS), sustained substantial damage during a contingency landing during a test flight at Chase Industrial airport (TX2), Beeville, TX.

This aircraft is a large UAS with 12 electric motors and 12 propellers mounted in the horizontal or near-horizontal plane. It is a developmental platform for unmanned cargo operations. The pilot does not control the flight path, speed or attitude of the aircraft in flight, all flights are preprogrammed. The only ability the pilot or ground control station operator has to affect the flight is through contingency management via the "abort to planned zone" (APZ), "land now" or "cut power" (terminate the flight) commands.

Flight testing of the aircraft had been going on for several weeks, with approximately 45 flights completed. Test flights were very short in duration, no longer than 4 minutes. According to the manufacturer/operator, the accident flight was a planned 30 knot flight over the grass area between the runway and the taxiway. All preparations for the flight were normal. After takeoff and turning on course to parallel the runway/taxiway, the aircraft started to deviate from the programmed flight profile. The flight test area included a two-level geo-fence boundary to keep the aircraft contained within a safe area. The aircraft identified the deviation and autonomously triggered an "abort to planned zone" (APZ). The APZ is a contingency plan where the aircraft stops the current flight and immediately turns towards the closest planned landing zone (in this case, the taxiway) and begins the approach. However, the aircraft continued the lateral deviation. The aircraft reached the first geo-fence boundary and then autonomously executed a "land now" command where the aircraft immediately begins a landing regardless of its position. The aircraft appeared to adjust pitch attitude for the abort to planned zone landing and drifted towards the second geo-fence boundary. Upon reaching the outer geo-fence, the aircraft autonomously cut power to all motors and dropped to the ground, as designed. The aircraft was substantially damaged, there were no injuries. The aircraft remained within the test area.

A review of the flight data by the manufacturer/operator revealed that the lateral deviation initiated due to higher than expected and accounted for wind, which resulted in high vibration within the aircraft navigation system. The contingency logic was unable to return the aircraft to the planned abort zone prior to reaching the outer geo-fence. The manufacturer/operator determined that there had been insufficient tests related to high crosswinds, and insufficient ability to determine winds during test flights. Additionally, the manufacturer/operator determined that the physical separation between the abort to planned zone (APZ) and geo-fence locations was inadequate for the aircraft to maneuver considering the wind and other environmental factors.

Probable Cause and Findings

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

A higher than expected and accounted for crosswind which initiated a lateral deviation, and resulted in the aircraft reaching the limits of the geo-fence area triggering a contingency forced landing. 

Findings

Aircraft

Maximum crosswind component - Capability exceeded (Cause)

Global positioning sys (GPS) - Capability exceeded (Cause)

Factual Information

History of Flight

Enroute

Nav system malfunction/failure (Defining event)

Emergency descent

Off-field or emergency landing

 

 

Pilot Information

Certificate:

Flight Instructor; Commercial

Age:

51

Airplane Rating(s):

Multi-engine Land; Single-engine Land

Seat Occupied:

None

Other Aircraft Rating(s):

Gyroplane; Helicopter

Restraint Used:

 

Instrument Rating(s):

Airplane; Helicopter

Second Pilot Present:

 

Instructor Rating(s):

Gyroplane; Helicopter; Instrument Helicopter

Toxicology Performed:

 

Medical Certification:

Class 2 With Waivers/Limitations

Last FAA Medical Exam:

12/06/2018

Occupational Pilot:

Yes

Last Flight Review or Equivalent:

03/28/2019

Flight Time:

5662 hours (Total, all aircraft), 1 hours (Total, this make and model), 5326 hours (Pilot In Command, all aircraft), 14 hours (Last 90 days, all aircraft)

 

 

Aircraft and Owner/Operator Information

Aircraft Make:

BOEING

Registration:

N243XT

Model/Series:

CV2

Aircraft Category:

Helicopter

Year of Manufacture:

 

Amateur Built:

No

Airworthiness Certificate:

 

Serial Number:

004

Landing Gear Type:

Ski

Seats:

0

Date/Type of Last Inspection:

03/20/2019,

Certified Max Gross Wt.:

1200 lbs

Time Since Last Inspection:

 

Engines:

 

Airframe Total Time:

4.5 Hours at time of accident

Engine Manufacturer:

 

ELT:

Not installed

Engine Model/Series:

 

Registered Owner:

Boeing

Rated Power:

 

Operator:

Boeing

Operating Certificate(s) Held:

None

 

Meteorological Information and Flight Plan

Conditions at Accident Site:

Visual Conditions

Condition of Light:

Day

Observation Facility, Elevation:

 

Distance from Accident Site:

 

Observation Time:

 

Direction from Accident Site:

 

Lowest Cloud Condition:

Scattered / 2000 ft agl

Visibility

 

Lowest Ceiling:

 

Visibility (RVR):

 

Wind Speed/Gusts:

10 knots / 6 knots

Turbulence Type Forecast/Actual:

/

Wind Direction:

 

Turbulence Severity Forecast/Actual:

/

Altimeter Setting:

 

Temperature/Dew Point:

 

Precipitation and Obscuration:

 

Departure Point:

Beeville, TX (TX2)

Type of Flight Plan Filed:

None

Destination:

Beeville, TX (TX2)

Type of Clearance:

None

Departure Time:

 CDT

Type of Airspace:

Class G

 

Airport Information

Airport:

Beeville (TX2)

Runway Surface Type:

 

Airport Elevation:

184 ft

Runway Surface Condition:

 

Runway Used:

13

IFR Approach:

None

Runway Length/Width:

8000 ft / 200 ft

VFR Approach/Landing:

None

 

Wreckage and Impact Information

Crew Injuries:

N/A

Aircraft Damage:

Substantial

Passenger Injuries:

N/A

Aircraft Fire:

None

Ground Injuries:

N/A

Aircraft Explosion:

None

Total Injuries:

N/A

Latitude, Longitude:

28.363611, -97.664167


Administrative Information

Investigator In Charge (IIC):

William R English

Report Date:

03/27/2020

Additional Participating Persons:

 

Publish Date:

03/27/2020

Note:

This accident report documents the factual circumstances of this accident as described to the NTSB.

Investigation Docket:

http://dms.ntsb.gov/pubdms/search/dockList.cfm?mKey=99683





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