# SUAS Crash Investigation

If you don’t figure out why your unmanned aircraft crashed then you will crash it the same way in the

future.

© Alfred A. Gates, 2014

1

# Crash Investigation Tools

• Flight data recording

– Video camera recording from flight

– On board SD card

– Recording through a ground control station link



### • Weather

• Pilot control observations

• Observer observations

• Crash site

• Internet search on make model common crash's

© Alfred A. Gates, 2014 2

# Crash Investigation

• Pilot: Did the aircraft operate as expected



## • Observer: What happened prior to crash and what is the camera doing

• Weather: What are the winds and is it raining or snowing

© Alfred A. Gates, 2014 3

# Crash Investigation, Aircraft Behavior Prior to Crash What to Look For

• Rapid spinning (YAW) and pitch or roll in one direction: Loss of power to one or more arms. (Prop, ESC or Motor failure)

• Controlled roll and or pitch in one direction and controlled flight by AP in that direction: GPS signal loss

• Slowly or quickly losing altitude: Battery low, loss of power

• Increasing pitch and or roll oscillations of aircraft: Autopilot tuning problem.

• Uncontrolled pitch and or roll and YAW, loss of attitude:

• Typically the aircraft will pitch and or roll to an angle and maintain the angle. The angle will be steep and the aircraft will dive External or onboard electromagnetic interference, autopilot problems.

© Alfred A. Gates, 2014 4

# Inflight Observations

© Alfred A. Gates, 2014 5 Dropping slowly or quickly Loss of power

Rapidly spinning out of control Failure of propeller ESC,
motor or connection Sharp angle

and flight in a direction GPS signal loss Rapid increasing oscillation Autopilot tuning problem

Observation and possible cause Aircraft YAWs and rolls and attitude is lost: Electromagnetic interference, autopilot problems

# Crash Site Investigation

• Debris field

– Wreckage in one location

• Human error, autopilot or electronics failure



### – Wreckage spread over a large area

• Break up in flight inspect parts to determine point of failure



### – Aircraft in one location with a missing component

• Missing component has something to do with the failure

© Alfred A. Gates, 2014 6

# Aircraft Investigation, Crash Site

• Do not pick up the aircraft (Batteries may be 

## connected and burning)

• Take pictures

• Locate: All propellers, motors and ESC

• Check: Propellers are they tight, motors lose or tight, are ESC plugged into the autopilot and motors, is the autopilot loose, is the battery connected

© Alfred A. Gates, 2014 7

# Aircraft Crash Investigation

• Difficult to separate the actual crash from the cause

• Are props hubs tightly bolted on the motors

– (Props can be broken but the hubs should be tightly mounted)



### • Are the motors securely mounted to the arms

– (Motors must be bolted down tightly)



### • Dose the ESC look burnt or do they smell

– (They could burn out after impact)



### • If the aircraft is intact are the ESC wires plugged in to the AP

• Is the battery pack damage is it plugged in

• If the arm are bolted on are the bolts tight



### • Is the autopilot loose

© Alfred A. Gates, 2014 8

# Internet, 3DR IRUS Crash Problems

© Alfred A. Gates, 2014 9© Alfred A. Gates, 2014 10© Alfred A. Gates, 2014 11

# Autopilot Failure

Inflight Observation: Steep bank and Yaw Ground Observation: Wreckage at one location What failed: Loss of Attitude Control 

## Cause: Electromagnetic Interference

Video: See directory

© Alfred A. Gates, 2014

12

# Autopilot Failure Inflight Observation: Steep bank and Yaw Ground Observation: Wreckage at one location What failed: Loss of Attitude Control Cause: Electromagnetic Interference Internal

Video: See directory

© Alfred A. Gates, 2014

13© Alfred A. Gates, 2014 14

# Structural Failure

Inflight Observation: Aircraft spinning and loss of control Ground Observation: Wreckage at one location except for 1⁄2 of a propeller

What failed: Propeller break up in flight Cause: Flight with a damage or poorly manufactured propeller

Video : https:// www.youtube.com/watch?v=m7KiJgMU75Y

Note: The aircraft will do the same thing with a ESC failure, motor failure, include a wiring disconnection

Replace all propellers with higher strength propellers. Replace propellers over time due to UV damage

Preflight: Check for damaged propellers Check tightly fitting propellers Check security of motor mounts Check ESC wire connections © Alfred A. Gates, 2014 15

# GPS Signal Loss Inflight Observation: Aircraft will bank in a direction can continue to fly in that direction (typically) Ground Observation: Wreckage at one location What failed: Loss of GPS signal Cause: Flight around structure that blocked the GPS

signal, poorly trained pilot

Video: https :// www.youtube.com/watch?v=G8jPO_mXWDw Clamed GPS signal loss Video: https://www.youtube.com/watch?v=_ U8iHn_2l0U Looks like LTR mode GPS loss and switched in ATT model and was unable to fly the aircraft

Pilot requires training

© Alfred A. Gates, 2014 16

# Unexplained Loss of Control
Inflight Observation: Aircraft will bank and YAW in a direction or start to oscillate in pitch or roll Ground Observation: Wreckage at one location What failed: On board electromagnetic interference or

autopilot tuning??? Cause: Location of onboard electronics or tuning of aircraft

Video: https :// www.youtube.com/watch?v=OZkMxGgz8b8 Several similar crashes

Auto pilot tuning problem

Determine cause: Through internet search and testing of components. If you don’t figure out why your unmanned aircraft crashed then you will crash it the same way in the future.

© Alfred A. Gates, 2014 17

# After A Crash

• Determine the cause



## • Disassemble aircraft and inspect components

• Replace parts and assemble

• Bench test



## • Flight test all modes all maneuvers

• Ready for service

• DO NOT FLY AIRCRAFT UNTILL THE CAUSE 

## HAS BEEN IDENTIFIED

© Alfred A. Gates, 2014 18