Winch Motor Control Feedback Unavailable
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Applicable alarms (1)
MOTOR_CONTROL_FEEDBACK_WINCH_UNAVAILABLE
Likely outcomes — click to expand
Based on 171 missions where this alarm fired in the last 90 days as of 2026-10-13
Grounding vs discrepancy (of 43 ZERP issues filed on these missions)
Frequently replaced parts
| Part | P/N | Removals |
|---|---|---|
| 24078-008 | 24078 | 40 |
| PARALAND ASSY, DROID, P2 | 18427 | 21 |
| RIGHT DOOR ASSY, DROID, P2 | 21827 | 18 |
| LEFT DOOR ASSY, DROID, P2 | 21830 | 18 |
| BRAIN, LRU, DROID, P2 | 31920 | 15 |
Aggregated from fleet operations and refreshed daily. Individual outcomes may vary by site and configuration.
Background
Section titled “Background”This alarm occurs when Zip Exec has not received winch motor control feedback within the watchdog timeout. It is common to see this alarm on startup; however, if the alarm persists, it will block launch and prevent Zip Exec from commanding takeoff.
Exec watchdog alarm
Section titled “Exec watchdog alarm”- MOTOR_CONTROL_FEEDBACK_WINCH_UNAVAILABLE
Troubleshooting Steps
Section titled “Troubleshooting Steps”graph TD
enter-the-diagnostics-mode["<small><b>Step 1</b></small><br/>Action: Enter the Diagnostics Mode."]
can-the-aircraft-perform-a-droid-raise{"<small><b>Step 2</b></small><br/>Question: Can the Aircraft perform a Droid rais..."}
the-aircraft-may-return-to-service("<small><b>Step 3</b></small><br/>Reference: The Aircraft may return to service.")
are-winch-lights-on{"<small><b>Step 4</b></small><br/>Question: Are winch lights ON?"}
look-at-distro-b-power-status-and-see-i["<small><b>Step 5</b></small><br/>Action: Look at /distro_b.power_status and ..."]
check-for-any-loose-connectors["<small><b>Step 6</b></small><br/>Action: Check for any loose connectors."]
inspect-the-flex-harness-standoffs-on-t{"<small><b>Step 7</b></small><br/>Question: There are two root causes of a physic..."}
replace-the-docking-fin-winch-assembly["<small><b>Step 8</b></small><br/>Action: Replace the Docking Fin Winch Assembl..."]
replace-the-docking-fin-to-tail-node-fl["<small><b>Step 9</b></small><br/>Action: Replace the Docking fin to tail node ..."]
perform-a-droid-raise-and-lower-test-up["<small><b>Step 10</b></small><br/>Action: Perform a Droid raise and lower test ..."]
is-the-issue-resolved{"<small><b>Step 11</b></small><br/>Question: Is the issue resolved?"}
the-aircraft-may-return-to-service-2("<small><b>Step 12</b></small><br/>Reference: The Aircraft may return to service.")
escalate-to-the-owner-of-the-swapped-ha{{"<small><b>Step 13</b></small><br/>Escalation: Escalate to the owner of the swapped ..."}}
enter-the-diagnostics-mode --> can-the-aircraft-perform-a-droid-raise
can-the-aircraft-perform-a-droid-raise -->|Yes| the-aircraft-may-return-to-service
can-the-aircraft-perform-a-droid-raise -->|No| are-winch-lights-on
are-winch-lights-on -->|Winch lights are ON| inspect-the-flex-harness-standoffs-on-t
are-winch-lights-on -->|Winch lights are OFF| look-at-distro-b-power-status-and-see-i
look-at-distro-b-power-status-and-see-i --> check-for-any-loose-connectors
inspect-the-flex-harness-standoffs-on-t -->|Yes| replace-the-docking-fin-winch-assembly
inspect-the-flex-harness-standoffs-on-t -->|No| replace-the-docking-fin-to-tail-node-fl
replace-the-docking-fin-winch-assembly --> perform-a-droid-raise-and-lower-test-up
replace-the-docking-fin-to-tail-node-fl --> perform-a-droid-raise-and-lower-test-up
perform-a-droid-raise-and-lower-test-up --> is-the-issue-resolved
is-the-issue-resolved -->|Yes| the-aircraft-may-return-to-service-2
is-the-issue-resolved -->|No| escalate-to-the-owner-of-the-swapped-ha
style enter-the-diagnostics-mode fill:#dcfce7,stroke:#22c55e,color:#14532d
style can-the-aircraft-perform-a-droid-raise fill:#dbeafe,stroke:#3b82f6,color:#1e3a5f
style the-aircraft-may-return-to-service fill:#f3e8ff,stroke:#a855f7,color:#581c87
style are-winch-lights-on fill:#dbeafe,stroke:#3b82f6,color:#1e3a5f
style look-at-distro-b-power-status-and-see-i fill:#dcfce7,stroke:#22c55e,color:#14532d
style check-for-any-loose-connectors fill:#dcfce7,stroke:#22c55e,color:#14532d
style inspect-the-flex-harness-standoffs-on-t fill:#dbeafe,stroke:#3b82f6,color:#1e3a5f
style replace-the-docking-fin-winch-assembly fill:#dcfce7,stroke:#22c55e,color:#14532d
style replace-the-docking-fin-to-tail-node-fl fill:#dcfce7,stroke:#22c55e,color:#14532d
style perform-a-droid-raise-and-lower-test-up fill:#dcfce7,stroke:#22c55e,color:#14532d
style is-the-issue-resolved fill:#dbeafe,stroke:#3b82f6,color:#1e3a5f
style the-aircraft-may-return-to-service-2 fill:#f3e8ff,stroke:#a855f7,color:#581c87
style escalate-to-the-owner-of-the-swapped-ha fill:#fef3c7,stroke:#f59e0b,color:#78350f Hover or focus a block to preview it. Select the block to keep the preview open.
1 action
Enter the Diagnostics Mode.
2 question
Can the Aircraft perform a Droid raise and lower three (3) times?
3 reference
The Aircraft may return to service.
4 question
Are winch lights ON?
5 action
Look at
/distro_b.power_status and see if any alarms are present. 6 action
Check for any loose connectors.
7 question
There are two root causes of a physical comms issue on the winch:
- The standoffs on the winch PCBA can get damaged and tear out.
- The flex harness going to the winch is damaged.
Inspect the flex harness standoffs on the winch PCBA. Look for signs of the standoff being pulled out of the board, such as cracked solder or a very obvious tear out. Is damage present?
- The standoffs on the winch PCBA can get damaged and tear out.
- The flex harness going to the winch is damaged.
Inspect the flex harness standoffs on the winch PCBA. Look for signs of the standoff being pulled out of the board, such as cracked solder or a very obvious tear out. Is damage present?
8 action
Replace the Docking Fin Winch Assembly:
1. Link the issue as “Caused by” [Root Cause] [EV2] Winch pem nut standoff tears off and causes comms issues and assign to Johnny Sun.
2. Swap the winch motor following UMM Winch Assembly - Remove and Install.
3. Send the damaged motor to the Aviary addressed to Johnny Sun.
1. Link the issue as “Caused by” [Root Cause] [EV2] Winch pem nut standoff tears off and causes comms issues and assign to Johnny Sun.
2. Swap the winch motor following UMM Winch Assembly - Remove and Install.
3. Send the damaged motor to the Aviary addressed to Johnny Sun.
9 action
Replace the Docking fin to tail node flex harness:
1. Link the issue as “Caused by” [Root Cause] Winch Flex - Trace Cracking and assign to Kunal Verma.
2. Swap the flex following UMM Remove and Install PCB Harness and Standard Practices.
3. Send the damaged flex to the Aviary addressed to Kunal Verma.
1. Link the issue as “Caused by” [Root Cause] Winch Flex - Trace Cracking and assign to Kunal Verma.
2. Swap the flex following UMM Remove and Install PCB Harness and Standard Practices.
3. Send the damaged flex to the Aviary addressed to Kunal Verma.
10 action
Perform a Droid raise and lower test up to three (3) times.
11 question
Is the issue resolved?
12 reference
The Aircraft may return to service.
13 escalation
Escalate to the owner of the swapped hardware:
- Winch: Powertrain (P2 Firmware Motors On Call)
- Winch flex: Avionics (P2 Avionics Hardware On Call)
- Winch: Powertrain (P2 Firmware Motors On Call)
- Winch flex: Avionics (P2 Avionics Hardware On Call)
Resolution note
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Inspect the Winch
Section titled “Inspect the Winch”There are two root causes of a physical comms issue on the winch:
- The standoffs on the winch PCBA can get damaged and tear out.
- The flex harness going to the winch is damaged.
Follow the steps below to determine which one is damaged.
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