ERROR_MIXED_MOTOR_RESISTANCE
Applicable alarms (1)
Likely outcomes — click to expand
Based on 4 missions where this alarm fired in the last 90 days as of 2026-10-13
Grounding vs discrepancy (of 1 ZERP issues filed on these missions)
Aggregated from fleet operations and refreshed daily. Individual outcomes may vary by site and configuration.
Background
Section titled “Background”This alarm occurs when high resistance is detected in the mixed motor’s DC power path. Different internal mixed motor busbar resistance batches may contribute to the measured resistance.
Validator Results
Section titled “Validator Results”You can check the validator results for the failed mission on Baraza by adding the flight_id and inspecting the results for power_line_resistance/mixed. You can expand the Details section and review the reported values. The validator, which has lower thresholds than the alarm, fails if the max resistance exceeds the threshold. These results have no effect on the triaging steps, but are good to determine how much the mission failed by to inform us on the likelihood that we will find the issue.
Troubleshooting Steps
Section titled “Troubleshooting Steps”graph TD
assign-the-work-order["<small><b>Step 1</b></small><br/>Action: Assign the work order **Troubleshoot..."]
are-there-signs-of-loose-fasteners{"<small><b>Step 2</b></small><br/>Question: Inspect the Mixed Busbar / PDB connec..."}
replace-fasteners-and-reseat-to-proper-torque["<small><b>Step 3</b></small><br/>Action: Replace the fasteners and reseat to p..."]
are-there-signs-of-cross-threading-at-the-pdb-zdb{"<small><b>Step 4</b></small><br/>Question: Are there signs of cross-threading at..."}
replace-pdb-zdb-on-aircraft["<small><b>Step 5</b></small><br/>Action: Replace the PDB/ZDB on the aircraft."]
are-there-signs-of-damage-at-the-ring-terminal-connection{"<small><b>Step 6</b></small><br/>Question: Are there signs of damage, bent rings..."}
replace-ama-swap-mixed-motor-and-add-discrepancy["<small><b>Step 7</b></small><br/>Action: 1. Replace the Aft Motor Assembly on ..."]
have-off-nominals-been-discovered-and-resolved{"<small><b>Step 8</b></small><br/>Question: Have off-nominals been discovered and..."}
is-an-mx-dock-available{"<small><b>Step 9</b></small><br/>Question: Is an MX dock available to run a pref..."}
did-the-alarm-persist-after-preflight{"<small><b>Step 10</b></small><br/>Question: Run a preflight check with motors. Di..."}
escalate-to-busbars-on-call{{"<small><b>Step 11</b></small><br/>Escalation: Escalate to P2 Busbars On Call."}}
return-aircraft-to-service["<small><b>Step 12</b></small><br/>Action: Return the aircraft to service."]
assign-the-work-order --> are-there-signs-of-loose-fasteners
are-there-signs-of-loose-fasteners -->|Yes| replace-fasteners-and-reseat-to-proper-torque
are-there-signs-of-loose-fasteners -->|No| are-there-signs-of-cross-threading-at-the-pdb-zdb
replace-fasteners-and-reseat-to-proper-torque --> are-there-signs-of-cross-threading-at-the-pdb-zdb
are-there-signs-of-cross-threading-at-the-pdb-zdb -->|Yes| replace-pdb-zdb-on-aircraft
are-there-signs-of-cross-threading-at-the-pdb-zdb -->|No| are-there-signs-of-damage-at-the-ring-terminal-connection
replace-pdb-zdb-on-aircraft --> are-there-signs-of-damage-at-the-ring-terminal-connection
are-there-signs-of-damage-at-the-ring-terminal-connection -->|Yes| replace-ama-swap-mixed-motor-and-add-discrepancy
are-there-signs-of-damage-at-the-ring-terminal-connection -->|No| have-off-nominals-been-discovered-and-resolved
replace-ama-swap-mixed-motor-and-add-discrepancy --> have-off-nominals-been-discovered-and-resolved
have-off-nominals-been-discovered-and-resolved -->|Yes| is-an-mx-dock-available
have-off-nominals-been-discovered-and-resolved -->|No| escalate-to-busbars-on-call
is-an-mx-dock-available -->|Yes| did-the-alarm-persist-after-preflight
is-an-mx-dock-available -->|No| return-aircraft-to-service
did-the-alarm-persist-after-preflight -->|Yes| escalate-to-busbars-on-call
did-the-alarm-persist-after-preflight -->|No| return-aircraft-to-service
style assign-the-work-order fill:#dcfce7,stroke:#22c55e,color:#14532d
style are-there-signs-of-loose-fasteners fill:#dbeafe,stroke:#3b82f6,color:#1e3a5f
style replace-fasteners-and-reseat-to-proper-torque fill:#dcfce7,stroke:#22c55e,color:#14532d
style are-there-signs-of-cross-threading-at-the-pdb-zdb fill:#dbeafe,stroke:#3b82f6,color:#1e3a5f
style replace-pdb-zdb-on-aircraft fill:#dcfce7,stroke:#22c55e,color:#14532d
style are-there-signs-of-damage-at-the-ring-terminal-connection fill:#dbeafe,stroke:#3b82f6,color:#1e3a5f
style replace-ama-swap-mixed-motor-and-add-discrepancy fill:#dcfce7,stroke:#22c55e,color:#14532d
style have-off-nominals-been-discovered-and-resolved fill:#dbeafe,stroke:#3b82f6,color:#1e3a5f
style is-an-mx-dock-available fill:#dbeafe,stroke:#3b82f6,color:#1e3a5f
style did-the-alarm-persist-after-preflight fill:#dbeafe,stroke:#3b82f6,color:#1e3a5f
style escalate-to-busbars-on-call fill:#fef3c7,stroke:#f59e0b,color:#78350f
style return-aircraft-to-service fill:#dcfce7,stroke:#22c55e,color:#14532d Hover or focus a block to preview it. Select the block to keep the preview open.
Are there any signs of cross threading or loose bolts?
2. Add a work order to remove and replace the Mixed Motor from the Aft Motor Assembly.
3. Create a discrepancy on the Mixed Motor with the discovered damage.
Resolution note
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