Nov 13, 2022 - Phoenix RCA

📋Incident overview

Postmortem owner	Anthony Luo
Airframe	Phoenix (BIG)
Pilot in charge	Anthony Luo
Visual Observers	Aidan Bowers (Deactivated) Megan Spee Conall Kingshott
Related incidents	Vanny in SDC April 2022?
Incident date	13 Nov 2022
Approx. Damage Costs	~ 20$
Report Date	13 Nov 2022

🔮 Executive summary

BIG version of Phoenix was being flown on 5s to collect training data on Landing Pads for CV. Shortly after takeoff, all motors stopped and the frame fell to the ground. On scene, phoenix was smoking/smouldering. Batteries were unplugged without further incident.

⏱ Incident timeline

Describe (approximate) timelines, cross correlate with telemetry/video recordings/etc if any.

[t -7 mins] Phoenix landed after previous flight test, one chipped prop was being replaced.

[t -5 mins] Decision to use 5s batteries as 3s batteries were no longer available.

[t -3 mins] Batteries on, phone taped to bottom of phoenix for footage.

[t -1 mins] Takeoff, successful flight

[t -30s] Power dipped, phoenix rapidly descended

[t -15s] Full throttle applied, phoenix climbed

[t -0s] Motor cutoff, phoenix falls from the sky.

[t +15s] Anthony arrived at phoenix and unplugged the battery.

[t + 30s] phoenix has been moved to the sidewalk and conall is cutting tape away.

https://youtu.be/2AoTWLfbJHI

⛑ Postmortem report

Instructions

Report

Leadup

List the sequence of events that led to the incident.

Unclear. Potentially: unprotected circuits inside the frame, loose cabling, water damage, overheating motor connections?

🙅‍♀️ Fault

Describe what didn't work as expected. If available, include relevant data visualizations.

PDB ended up burning a hole through itself.

👁 Detection

Report when the team detected the incident and how they knew it was happening. Describe how the team could've improved time to detection.

Analysis was done in the bay, when we realized that the PDB on phoenix had scorch marks, as did the pizza box underneath the pdb.

🙋‍♂️ Response

Report who responded to the incident and describe what they did at what times. Include any delays or obstacles to responding.

Batteries unplugged upon arrival at crash.
Drone moved to safe location clear of flammable materials (middle of road or sidewalk - was I prepared to chuck it? yes.)
Electronics recovered from airframe.

🙆‍♀️ Recovery

Report how the user impact was mitigated and when the incident was deemed resolved. Describe how the team could've improved time to mitigation.

< help Aidan Bowers (Deactivated) >

Perhaps telemetry logging to prevent this from happening?

🔎Five whys root cause identification

Run a 5-whys analysis to understand the true causes of the incident.

why did pdb short?

→ 5s? but it’s rated for 2-12s

→ electrical loose connections? then how did it recover

→ ?!??!?!?

🗃Related records

Check if any past incidents could've had the same root cause. Note what mitigation was attempted in those incidents and ask why this incident occurred again.

Vanny short april 2022?

🤔 Lessons learned

Describe what you learned, what went well, and how you can improve.

Electrical Isolation, waterproofing, check cables before flight?

✅ Recommendations for future

Actionable Recommendation	Reasoning
Double check electrical connections before flying	Helps identify if connections may short.
Remove electrically conductive items from the PCB?
Check for water before flight.