Risk register and mitigation status
The design failure mode and effects analysis (DFMEA), dated September 13, 2026 on Sheet1, lists enclosure, circuit and software concerns and recommended actions. Its risk priority number (RPN) is the product of the team’s severity, occurrence and detection scores. It is a prioritization value, not a probability of failure or evidence that a mitigation works. The selected values below reproduce the source products. DFMEA
| Source risk | Severity × occurrence × detection | Source RPN | Source-design response/recommended work | Verification home |
|---|---|---|---|---|
| Loss of emergency protections from electrical failure | 8 × 6 × 5 | 240 | Electrical design review and testing across operating conditions | T04 |
| Software bug causing loss of control | 9 × 4 × 6 | 216 | Debugging and controls testing | T04 |
| Emergency switch/relay coil failure, Sheet2 | 9 × 3 × 7 | 189 | Review/test cutoff architecture; source proposes additional fuse protection | T04 |
| Pressure-sensor programming/data failure, Sheet2 | 8 × 4 × 5 | 160 | Debug pressure sensing and relay shutdown | T04 |
| Inadequate enclosure sealing | 8 × 6 × 3 | 144 | Coating/sealing evaluation and moisture monitoring proposed | T03 |
| Magnetic encoder misalignment/field loss, Sheet2 | 7 × 4 × 5 | 140 | Throttle plausibility/timeout and switch testing proposed | T04 |
| Electronics overheating | 8 × 7 × 2 | 112 | Extended operation and temperature monitoring | T06 |
| Water ingress detection failure/slow response, Sheet2 | 9 × 3 × 4 | 108 | Probe placement and shutdown logic proposed | T03, T04 |
| Structural integrity loss | 9 × 2 × 3 | 54 | Structural simulation and physical evaluation proposed | A05, T03 |
The workbook also addresses penetrator sealing, cable insulation, broken connections, overcurrent, unintended power switching, propeller interference, buck regulation and sensor signal protection. These are design concerns and proposed controls; attachment wording that calls a sensor/code/fuse a “current control” does not establish tested installation. Sheet1 action-results fields are blank for the cited rows, so no reduced post-action RPN or closed mitigation is asserted.
Documented progress and next work
| Milestone/source stage | Supported outcome | Next evidence needed |
|---|---|---|
| April 19 report | Research, targets, concept selection and preliminary analysis documented | Reconciled requirements and model basis |
| August 26 / September 7–9 scope discussions | Smaller functional demonstration and separate mockup/sealing concepts defined | Exact as-built hardware and completed-demo records |
| September 13 DFMEA | Risk priorities and recommended work recorded | Completed action/test evidence |
| SD2 check-in 2 | Battery placement and enclosure/control/PCB designs advanced | Physical integration and qualified component identities |
| SD2 check-in 3 | Preliminary startup and fit-led iteration reported, T02, T04 | Quantitative propulsion, sensor/fault, enclosure and endurance results |
| Enclosure record with September 29 filename | Thread/opening revision and further reference-print/testing work described | Final material/seal/revision and T03 evidence |
The practical lessons supported by this record are that model geometry changes alter sizing predictions, scoring methods can change a concept ranking, physical prints expose interface problems, and budget changes require separating the demonstration from the full product intent. The next steps are to settle the requirements/as-built basis, verify the remaining electrical interfaces, qualify the enclosure, measure thrust and endurance, and evaluate the mounted configuration with users. Detailed acceptance targets and methods stay in Requirements and Validation.
The supplied Gantt workbook and the report’s nine proposed checkpoints are planning aids. Their dates/progress fields do not prove task completion, and no archived milestone is silently marked complete from the schedule alone. Project schedule