2023-04-01 - RCA Baby Ratel 2 Camera

1 Incident overview | 2 Executive summary | 3 Incident timeline | 4 Postmortem report | 5 Recommendations for future

Incident overview

Postmortem owner	@Hamza Ali
Airframe	Houston
Related incidents
Incident date	Mar 31, 2023
Approx. Damage Costs	$35
Report Date	Completed Apr 3, 2023

Executive summary

While testing and setting up the Baby Ratel 2 camera with the on-screen display for video testing on Houston, an incorrectly ordered JST-GH cable with a flipped positive and negative connection caused a short on the camera.

The short smoked the camera which is now fully unusable.

Incident timeline

The members testing the camera found a JST-GH cable that was unused and from a different product that was 3-pin and needed to be used to interface with the OSD.
The members disassembled the Camera + 1.3GHz VTX setup that was connected with no OSD
The members began assembly with the Houston flight controller, adding the camera and VTX to the OSD and connecting it to the power connectors on Houston
The members plugged in Houston with a 3S LiPo battery. A flipped positive and negative wire on the OSD connecting to the camera caused the camera to smoke out.
The power was promptly disconnected. No other damage has been reported, and all other parts have been tested and verified as working.

Postmortem report

Instructions	Report

Instructions

Report

Leadup

List the sequence of events that led to the incident.

The stock JST-GH to JST-XH was unable to be found
Members who were configuring and setting up Houston were unable to find the correct cable for days

Fault

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

The JST-GH connector wasn’t properly matched with the pin out of the OSD

The JST-GH connector for the bottom left port expects 5V on the end. However typical servo connectors have this wire in the center. Due to the color coding and use of servo extensions, the wire connection based on the traditional meaning of the colors (white for signal, red for positive, and black for ground) was misleading, and red was now negative and black was positive.
The order of the servo connectors to the camera was confirmed to be in the expected order, however was not matched on the OSD end

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.

Smoke was coming out of the Baby Ratel 2 camera
More rigorous validation and verification of the cable coming out of the OSD to the camera would have prevented this
Better labeling and organization of the stock connectors for this OSD would have also prevented the mislabelled wire being used in the first place
Whenever using a new cable, ensuring that the colors match up with the pin out on both ends would have prevented this

Response

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

As soon as smoke started coming out of the camera, it was immediately unplugged.
As the focus was on the VTX and seeing if it was plugging on, it took a couple seconds to notice and realize that the camera was smoking
As soon as the smoking was noticed the camera was instantly unplugged

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.

Houston was instantly unplugged and the wiring connections from the OSD to the camera, as well as to all other parts of the video setup were rigorously verified, including with a DMM to ensure that no other oversight was taking place.

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.

A similar issue was caused before the February 19th flight test where the negative and positive connectors on an ESC on cornflakes was flipped.

While the cause of the accident rhymed, the cause of this accident was due to trust that the cable we found matched the pin out. On the ESC, the accident was caused by incorrectly soldered cables.

Lessons learned

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

Taking more time to verify cables being used match the pin out correctly on both ends
Sanity-checking yourself once everything is connected before testing can help find more of these problems when issues slip through. Going through the full wiring once more after complete assembly can help prevent this in the future.

Recommendations for future

Actionable Recommendation	Reasoning

Actionable Recommendation	Reasoning
Sanity Test	Doing a rigorous visual inspection after assembly of your electric setup is never going to hurt. It can help prevent accidents like this happening in the future and is very low risk with high reward, given that it is done with proper care.
Get a second pair of eyes	Asking a friend to verify the wiring setup can be helpful, as they are likely to be more stringent with checking, especially if they were not the ones to setup the system with you.
Store fully setup systems together	Houston’s VTX system had been setup and verified to be working 2 weeks prior. However, since then, the specific wires being used are unable to be found, which caused the need for different wires to be used in the first place. Ensuring that fully setup systems are stored properly will make sure that future users of the system have less verification to do.
Consider usage of a DMM to verify long wires with lots of extensions	Where extensions and long wires are used, consider using a DMM to easily verify wiring.