Case Studies: Three Failures and the Lessons

These composite case studies show the module’s tools - Hierarchy of Controls, JSA, FMEA, and 5 Whys - working together on realistic FRC scenarios.

Case 1 - The brownout that lost a match. Late in a qualification match the robot froze; the roboRIO LED went amber and the Driver Station flashed red. Investigation: the DS Log Viewer showed brownout markers and a climbing 12V fault count right as the drivetrain and shooter spun up together. A Battery Beak test afterward read 0.022 Ohm internal resistance on the installed battery - above the 0.020 Ohm retire-it threshold. 5 Whys root cause: no pre-match battery testing and no current limits, so two subsystems peaked simultaneously and dragged the bus below the roboRIO 2.0’s default brownout threshold of 6.75V. Fixes (by hierarchy): engineering - set a TalonFX SupplyCurrentLimit of 70A dropping to 40A after 1.0s on the drivetrain, and gear so wheels slip near 45A; administrative - require a Beak test (>12.7V, <0.015 Ohm) before every match and a numbered battery log. Result: no further brownouts; the fix lives in code and process, not in ‘try a different battery.’

Case 2 - The battery fire that didn’t happen. During pit work a student noticed a battery’s case looked slightly swollen and warm. Response: per the team’s procedure, they did NOT recharge it; they quarantined it in the plastic bin from the battery spill kit, photographed it, and recycled it. Why it worked: the team had an FMEA entry for ‘damaged battery -> vent/fire’ (high severity, poor detection if no one inspects), which had driven an administrative control - ‘inspect every battery for bulging/leaking before and after every match.’ That single inspection habit caught a hazard before it became a fire. Lesson: a high-RPN, low-detectability failure mode is best controlled by a forced inspection step; the spill kit and quarantine bin were the engineering backup.

Case 3 - The pneumatic near-miss. A student reached in to reseat a fitting and a cylinder snapped shut, missing their fingers by an inch. Investigation (5 Whys): the system still held stored pressure because ‘the robot was off,’ and the team assumed off meant safe. Root cause: LOTO didn’t enforce venting stored energy. Fixes: added a manual vent step to the LOTO one-pager (‘vent until both gauges read 0 psi, then hand-verify’), and an FMEA re-score dropped the detection risk once ‘verify zero energy’ became mandatory. This is the exact failure mode (pneumatic vents while serviced, RPN 160) that topped the FMEA lesson - and the case shows why it deserved the top slot.

The throughline: every one of these was prevented or fixed not by a poster but by a system - a test, a log, an inspection step, a code limit, a verified procedure. That systems mindset, documented and lived by the whole team, is what real safety - and award eligibility - is built on.

Key takeaways

• Brownout case: untested battery (0.022 Ohm) plus no current limits; fix with SupplyCurrentLimit, gearing, and mandatory pre-match Beak tests.
• Battery-fire case: a forced inspection step (high RPN, low detectability) caught a swelling battery before ignition.
• Pneumatic case: ‘off’ is not ‘safe’ - adding a vent-and-verify LOTO step eliminated the top-RPN failure mode.

This lesson was adapted from learnfrc.com.