Nov 13, 2022 - Phoenix RCA
Incident overview
Postmortem owner | @Anthony Luo |
---|---|
Airframe | Phoenix (BIG) |
Related incidents | Vanny in SDC April 2022? |
Incident date | Nov 13, 2022 |
Approx. Damage Costs | ~ 20$ |
Report Date | Nov 13, 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.
Postmortem report
Instructions | Report |
---|---|
Leadup
| Unclear. Potentially: unprotected circuits inside the frame, loose cabling, water damage, overheating motor connections? |
Fault
| PDB ended up burning a hole through itself. |
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
|
|
Recovery
| < help @Aidan Bowers (Deactivated) > Perhaps telemetry logging to prevent this from happening? |
Five whys root cause identification
| why did pdb short? → 5s? but it’s rated for 2-12s → electrical loose connections? then how did it recover → ?!??!?!?
<help @Aidan Bowers (Deactivated) > |
Related records
| Vanny short april 2022? |
Lessons learned
| 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. |
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Photos