Yuneec H520 Martell Forest Incident Notes

            The purpose of this post is to create a general checklist for how UAS operations should be conducted as a result of the 3/26 Yuneec H520 crash to reduce in-field UAS incidents from occurring. 

Background:

            On the day of the operation, the weather as reported by the near by the KLAF airport METAR was 7 mph wind coming from the northeast, clear skies with 10 statute miles visibility with a temperature of 27 degrees Fahrenheit. The operating area, Martell Forest, was just west of the KLAF Class D airspace (see figure 1). Martell Forest, was located in a depression surrounded in hill covered trees. The area to be imaged was of a specific stand of trees as shown in figure 1. 

Figure 1: Martell Forest Location in Relation to KLAF

            The students drove to the Martell Forest location and were split into two groups. The first group set out the Propellor AeroPoints GCPs while the second group set up the UAS platform.

Setting up the Propellor Aeropoints GCPs:

            Aeropoint GCPs made by the company Propellor, are individual GCP targets with built-in survey grade GPS units. One sets them up at the beginning of a flight, overflies them during the data collection, then collects and uses their coordinates to correctly geolocate images. Figure 2 is an image of a Propellor Aeropoint GCP. 

Figure 2: Propeller Aeropoint GCP

            The GCPs were laid out in in a a well distributed pattern with some around the perimeter and some within the stand of trees being flown as shown in figure 3. This image was created by Hans-Olof Gustafsson and is used with his permission. Check out his blog linked here.

Figure 3: GCP Placement

*To learn more about how to properly place and use GCPs in your dataset, please refer to my February 14th post which walks you through the placement and processing when using GCPs.  

UAS Platform and Sensor Used: 

            The UAS system used was the Yuneec H520 with the E90 sensor (see figure 4).

Figure 4: Yuneec H520 with E90 Sensor

            The Yuneec H520 is a short range high endurance platform with approximately 25 minute flight time depending on the sensor. The sensor attached in the image above is the E90 sensor, a 20 megapixel RGB gimbaled sensor. The UAS uses the ST16S all-in-one controller with a built in tablet interface that allows the user to setup, view what the sensor sees, and adjust parameters in mid flight without the use of an external device (see figure 5).

Figure 5: ST16S all-in-one controller

Mission Planning:

            For data analysis purposes, the mission was planned for two flights each flown in a crosshatch pattern at 80 meters, one with the sensor at nadir, and the other with the sensor angled at 45 degrees. Figure 6 below is an image of the planned flight path.

Figure 6: Flight Path

UAS Setup and Calibration:

            When setting up the UAS, the battery and props were installed by Professor Hupy and the process of connecting to and calibrating the Yuneec H520’s compass, accelerometer, and gimbal were performed as a group. For the compass calibration, the hexacopter was rotated about all of its axes, following the instructions of the controller as shown in figure 7 and video 1. 

Figure 7: Compass Calibration

Video 1: Compass Calibration

            Once complete, the accelerometer of the hexacopter was calibrated by placing and holding the hexacopter in various orientations as dictated by the ST16S controller as shown in figure 8 and 9. Figure 8 shows the ST16S screen and figure 9 shows the hexacopter being held in one of the required orientations. 

Figure 8: Accelerometer Calibration Screen

Figure 9: Accelerometer Calibration Being Performed on Hexacopter

            After the accelerometer was done calibrating, the hexacopter was placed on the ground and the gimbal was started and the hexacopter automatically ran the calibration as shown in video 2 below.

The Flight:

            For the flight, Lucus Write was the remote pilot in command (RPIC) and I acted as the visual observer (VO). The Yuneec was armed and professor Hupy instructed Lucus to ascend to an altitude clear of the trees and test the controls. The takeoff went smoothly but as Lucus pulled back on the stick to get a feel for the hexacopter, the rear mounted battery came unclipped and left it with no power. The Hexacopter crashed and broke its landing gear and three of its arms. Video 3 shows the takeoff and subsequent crash. 

Post Crash Debrief:

            The cause of this crash was due to human error and bad design. When sliding the battery into place, it did not click and give positive feedback that it was connected and lock in. It partially locked which allowed it to be rotated and power the copter without ejecting however once in flight, it dislodged and caused the aircraft to lose power and crash. A design that allows the copter to be powered while the battery is not completely locked into place is a bad design and should be altered to correct it.

            To reduce the chance that a person may not correctly install the battery, checklists should be used with two or more items that have the operator check that the battery is properly installed. If the operator is not the one performing the preflight checks, he or she should still observe it to catch potential errors in the process.

Contributing factors that led to this incident included complacency, distraction, and lack of checklist use. 

• The complacency of thinking, “the Yuneec performed well yesterday, why should it be any different today” can be combated by creating and following a rigorous checklist. 
• During the setup and flight process there was a high level of distraction due to many students asking questions and crowding around trying to get pictures. This could be reduced by implementing a policy of no one hovering over or talking to the RPIC while the UAS is being setup. *Note: In the case of the Yuneec, the preflight setup can be streamed to a seperate screen so that the TA can explain the setup process while the RPIC is doing it. 
• The lack of checklist use with all of the preflight, flight, and postflight information listed could help avoid mistakes in the process and prevent them from happening again. The next section below is a general checklist of the things that one should check before, during after a flight.

General Checklist:

Before Heading to the Location

• Confirm location, date, and time with client(s)

• Confirm availability of observer

• Location clear of restricted or prohibited airspace

• Location is clear of controlled airspace
• If no: File LAANC for approval if available for the area
• If  LAANC not available and there are no COAs or Waivers, operation is a no-go.

• Area surveyed on Google maps and notes created for: 
• hazards/obstacles
• Power lines
• Telephone poles 
• Trees 
• Terrain 
• Fences 
• locations of persons or property in mission area
• Other manned aircraft activity 
• crop dusting 
• helicopter activity 
• skydiving activity 
• hang gliding / para-motoring / ultralight activities 
• Freeways, highways, roads 
• Radio tower locations for possible electromagnetic interference (EMI) and radio-frequency interference (RFI))
• Takeoff and landing location  

• Weather checked: 
• visibility >3SM
• ceiling >500ft above flight altitude, 2000ft horizontal separation
• precipitation
• Kp index
• wind direction and velocity
• sun angle (if applicable) 

• Batteries charged:
• Flight batteries charged
• Controller battery charged 
• Sensor batteries charged (if applicable)

• UAS airframe 
• General inspection
• cracks, dents, chips, loose or disconnected wires 
• Arms free of damage and swinging and latching mechanism in good working order 
• Landing gear and retract assembly (if applicable) inspect for damage.

• Software to update
• controller
• UAS system
• sensor payload package

• Sensor Package 
• correctly installed 
• boots up correctly 
• SD cards 
• empty 
• formatted for data files

• Emergency repair kit packed

• Controller
• Physical condition checked 
• antennas installed an unbroken 
• switches and gimbals move freely and correctly
• controller powers on 

On Location Preflight and Setup

• Location scouted for hazards and obstacles 

• GCPs setout and their location and ID recorded

•  Launch and recovery system setup and checked (if applicable)

• Antennas of controller and UAS installed

• controller powered up 

• flight plan (mission) setup
• type of flight 
• altitude 
• airspeed 
• overlap and sidelap
• sensor angle 

• Sensor lens cap removed

• UAS Arms folded out, checked locked in upright position 

• UAS powered on 

• Connection between controller and UAS established

• Satellite count >6

• Flight plan uploaded 

• UAS calibrated 
• Accelerometer 
• Magnetometer
• sensor gimbal (if applicable) 

• Feedback that sensor is ready to collect data
• visual indication on data package (lights) or
• in app sensor monitoring  

• Prop guards removed (if applicable)

• Props Straightened or installed as necessary

• Confirm gimbal movement free and correct

• Failsafes set 
• RTL at 20% battery
• RTH loss of link 
• Land in place if <5% battery

Flight

• UAS Armed

• Takeoff 

• Controls correct
• pitch forward / pitch back / roll left / roll right / yaw left / yaw right

• Climb to mission altitude

• Start mission
• Notes:
• During the mission, constantly monitor the UAS battery for sudden reductions in percentage caused by bad or old batteries. 
• Monitor the controller and UAS visually for anomalous behavior and errors.
• Orient yourself in the same direction as the UAS is facing at all times.

• Ensure sensor is collecting data (if possible). 

Post-flight

•  Sensor properly shut down

• UAS powered down

• SD cards collected and stored in a safe, known location

• Props folded or removed as necessary 
• Prop guards installed (if applicable)

• Sensor Package secured

•  Logbook entry 
• Date
• Time
• Location
• Weather
• Aircraft used
• Mission duration
• Pilot in command name
• Certificate #
• Notes
• Key Metadata
• Sensor used 
• Sensor coordinates 
• UAS coordinates 
• GCP type and coordinates 
• Altitude flown
• Camera angle 
• sensor overlap and sidelap
• Sun angle