Mixed Motor Model Mismatch
Applicable alarms (1)
Likely outcomes — click to expand
Based on 104 missions where this alarm fired in the last 90 days as of 2026-10-13
Grounding vs discrepancy (of 130 ZERP issues filed on these missions)
Top work orders
- EV2: Replace Aft Motor Assembly on Aircraft · MAINTENANCE_ACTION 36
- Perform Software Update on Aircraft · MAINTENANCE_ACTION 33
- EV2: Replace Mixed Motor on Aircraft Aft Motor Assembly · MAINTENANCE_ACTION 33
- EV2/EV3 Perform Preflight Without Motors · INSPECTION 27
- EV2/EV3 Diagnostics Test Without Motors · INSPECTION 16
Frequently replaced parts
| Part | P/N | Removals |
|---|---|---|
| AFT MOTOR ASSY, ZIP, P2 | 23548 | 256 |
| MIXED MOTOR ASSY, ZIP, P2 | 25263 | 231 |
| TAIL, STBD, ZIP, P2 | 21840 | 60 |
| TAIL ASSY PORT(LH), PRE-EV2, ZIP, P2 | 31280 | 57 |
| BATTERY ASSY, ZIP, P2 | 27158 | 33 |
Frequently co-occurring alarms (% of the 104 missions above)
Aggregated from fleet operations and refreshed daily. Individual outcomes may vary by site and configuration.
Background
Section titled “Background”The controller detected a mismatch between the measured mixed motor RPM and the controller’s internal model. This guide checks first for the known mixed motor shaft-slip signature, then moves to mixed motor and propeller inspection.
Troubleshooting Steps
Section titled “Troubleshooting Steps”graph TD
check-shaft-slip-template{"<small><b>Step 1</b></small><br/>Question: Follow Check Mixed Motor Shaft Slip..."}
replace-mixed-motor["<small><b>Step 2</b></small><br/>Action: Mixed motor shaft slip is indicated. ..."]
inspect-mixed-motor-and-propeller["<small><b>Step 3</b></small><br/>Action: Inspect the mixed motor and mixed pro..."]
was-damage-found{"<small><b>Step 4</b></small><br/>Question: Was damage found on the mixed motor o..."}
replace-damaged-component["<small><b>Step 5</b></small><br/>Action: Replace the damaged component and ret..."]
escalate-zip-controls{{"<small><b>Step 6</b></small><br/>Escalation: Escalate to P2 Zip Controls On Call."}}
check-shaft-slip-template -->|Yes, mixed motor shaft slip...| replace-mixed-motor
check-shaft-slip-template -->|No, mixed motor shaft slip ...| inspect-mixed-motor-and-propeller
inspect-mixed-motor-and-propeller --> was-damage-found
was-damage-found -->|Yes| replace-damaged-component
was-damage-found -->|No| escalate-zip-controls
style check-shaft-slip-template fill:#dbeafe,stroke:#3b82f6,color:#1e3a5f
style replace-mixed-motor fill:#dcfce7,stroke:#22c55e,color:#14532d
style inspect-mixed-motor-and-propeller fill:#dcfce7,stroke:#22c55e,color:#14532d
style was-damage-found fill:#dbeafe,stroke:#3b82f6,color:#1e3a5f
style replace-damaged-component fill:#dcfce7,stroke:#22c55e,color:#14532d
style escalate-zip-controls fill:#fef3c7,stroke:#f59e0b,color:#78350f Hover or focus a block to preview it. Select the block to keep the preview open.
EV2: Replace Aft Motor Assembly on Aircraft
EV3: Replace Aft Motor Assembly on Aircraft
References:
- 60.4.2.a Inspect Mixed Motor
- 60.5.2.a Inspect Mixed Propeller - General
- 60.5.1 Mixed Propeller Damage Limits
Resolution note
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