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Update the title following the format: Jan 01, 2023 - RCA Name

(blue star)Incident overview | (blue star) Executive summary | (blue star) Incident timeline | (blue star) Postmortem report | (blue star) Recommendations for future

📋Incident overview

Postmortem owner

Yuchen Lin

Object

Arduino Tracking Antenna

Related incidents

Incident date

Approx. Damage Costs

Report Date

🔮 Executive summary

During Mar 29th, Yuchen Lin is following the pre-flight check list to test the fully functionality of the tracking antenna. When the battery is plugged in, the buck convert caught on fire and result in the damage of a buck converter, GPS, Arduino and possibly a IMU.

⏱ Incident timeline

  • check for all necessary components

  • bring all components outside of the bay

  • plug in battery with tracking antenna plugged in

  • observe the buck caught on fire

  • immediately unplug the battery

  • Test the new buck converter without tracking antenna plugged in

  • plug in to test the tracking antenna but find out the arduino will kill the computer

Incident report:

The main reason of the incident is the GPS not being properly powered.

image-20240401-014603.png

This GPS model only supports 3.3v for power. The prototyped version of the tracking antenna used a LDO to convert 5V from arduino to 3.3v to power the GPS module. When the incident happened, there are two wires connected to the two 3.3v pin on the GPS module. One wire is 5v from arduino to LDO and then output 3.3v to the GPS module. Another wire is directly connecting the the system power(5v) to the GPS. The reason causing the buck converter (12v to 5v) on fire is because the Vin and Vout of the LDO are being connected to the together through the two 3.3v pin and shorted on the GPS module and cause the LDO being fried and eventually leads to short between VIN and GND on tracking antenna prototyping board input screw terminal.

This also result in the Arduino on the prototyping board will draw more than the spec of the USB port on a normal laptop and trigger the over current protection on the laptop. (warning: the LED indicator might make an illustion that the Arduino is still working)

recap

Issue 1:

  • after the buck convert caught on fire should immediately bring the whole system back to the bay and test under a monitored enviornment instead of with a battery. Since the battery does not have over-current protection. This might cause further issue to the rest of the system.

Issue 2:

  • Yuchen Lin assumes the system is working as expected. (Note: the system is fully powered tested a week before the incident happened)

  • Yuchen Lin propose a solution of flying 5v to 3.3v LDO solution instead of planning it out carefully with the EE team, which this may leads to people not knowing the GPS module powering detail.

⛑ Postmortem report

Instructions

Report

Instructions

Report

(warning) Leadup

List the sequence of events that led to the incident.

We were unsure of the specific procedure to deal with damaged LiPo batteries and escalated the situation until we got into contact with the departments who were aware of how to deal with the problem.

🙅‍♀️ Fault

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

We had to call the special constable as well as the fire department in order to successfully dispose of the batteries in a safe manner

👁 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.

🙋‍♂️ Response

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

🙆‍♀️ 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.

🔎Five whys root cause identification

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

🗃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.

🤔 Lessons learned

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

✅ Recommendations for future

Actionable Recommendation

Reasoning

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