MAINTENANCE_ACTION_REQUIRED
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Applicable alarms (1)
MAINTENANCE_ACTION_REQUIRED
Likely outcomes — click to expand
Based on 252 missions where this alarm fired in the last 90 days as of 2026-10-13
Grounding vs discrepancy (of 346 ZERP issues filed on these missions)
Top work orders
- EV2: Replace Hover Motor on Aircraft · MAINTENANCE_ACTION 31
- EV2: Replace Hover Propeller on Aircraft · MAINTENANCE_ACTION 25
- EV2/EV3 Diagnostics Test Without Motors · INSPECTION 22
- EV2: Replace Aft Motor Assembly on Aircraft · MAINTENANCE_ACTION 18
- EV2: Inspect Aircraft after Droid Left Behind (DLB) · MAINTENANCE_ACTION 17
Frequently replaced parts
| Part | P/N | Removals |
|---|---|---|
| HOVER MOTOR ASSY, CCW MOTOR, ZIP, P2 | 19607 | 256 |
| CW EV3 HOVER MOTOR ASSY, ZIP, P2 | 33333 | 190 |
| AFT MOTOR ASSY, ZIP, P2 | 23548 | 134 |
| CCW HOVER PROPELLER BLADE, ZIP, P2 | 29857 | 103 |
| T800 CW HOVER PROPELLER, ZIP, P2 | 31101 | 103 |
Frequently co-occurring alarms (% of the 252 missions above)
Aggregated from fleet operations and refreshed daily. Individual outcomes may vary by site and configuration.
Validators
Section titled “Validators”You may have also reached this guide from a failure on the following validators:
- busbar_status/mixed/has_voltage_retries_exceeded
- busbar_status/port_aft/has_voltage_retries_exceeded
- busbar_status/port_fwd/has_voltage_retries_exceeded
- busbar_status/stbd_aft/has_voltage_retries_exceeded
- busbar_status/stbd_fwd/has_voltage_retries_exceeded
Background
Section titled “Background”This alarm is triggered by these off_nominals:
LAN8770_TEMP_ABOVE_SPEC(mixed)LAN9370_TEMP_ABOVE_SPEC(hover)LAN9370_APPROACHED_OVERTEMP_SHUTDOWN(hover)MCU_TEMP_ABOVE_SPEC(all)MOTOR_OVERTEMPERATURE(mixed, hover, winch)MOTOR_PROVISIONED_INCORRECTLY(hover)BOARD_OVERTEMPERATURE(servo)POWER_STAGE_DEGRADED(servo)STALL_RETRIES_EXCEEDED(servo)FREE_SPINNING(winch)INVALID_ENCODER_CALIBRATION(servo, winch)OVERVOLTAGE(hover, mixed, servo, winch)VOLTAGE_RETRIES_EXCEEDED(all)
Background: Hover Motor and Mixed Motor–Overtemp Context
Section titled “Background: Hover Motor and Mixed Motor–Overtemp Context”This alarm is raised by a motor if it has self-assessed that it must receive maintenance before it can be returned to service.
Troubleshooting Steps
Section titled “Troubleshooting Steps”graph TD
follow-the-instructions-that-are-applica{"<small><b>Step 1</b></small><br/>Question: Select one active OFF_NOMINAL below, ..."}
motor-provisioned-incorrectly["<small><b>Step 2</b></small><br/>Action: Check for the HARDWARE_CONFIGURATION..."]
invalid-encoder-calibration["<small><b>Step 3</b></small><br/>Action: Perform SB-2025-024 parts A and C. Th..."]
free-spinning-dlb["<small><b>Step 4</b></small><br/>Action: Follow the DLB procedure. No need to ..."]
lock-mech-disconnected{"<small><b>Step 5</b></small><br/>Question: Inspect the docking fin flex connecti..."}
lock-mech-reattach["<small><b>Step 6</b></small><br/>Action: Reattach winch flex. Inspect the asse..."]
lock-mech-build-version{"<small><b>Step 7</b></small><br/>Question: What build version is the aircraft?"}
lock-mech-replace-docking-fin["<small><b>Step 8</b></small><br/>Action: Create a work order using Work Order..."]
lock-mech-replace-dwt-flex["<small><b>Step 9</b></small><br/>Action: Create a work order using Work Order..."]
free-spinning-no-dlb{"<small><b>Step 10</b></small><br/>Question: Inspect for line jumps/tangles in the..."}
free-spinning-untangle["<small><b>Step 11</b></small><br/>Action: Untangle the line, if practicable. If..."]
free-spinning-inspect-damage{"<small><b>Step 12</b></small><br/>Question: Inspect the line for damage, refer to..."}
free-spinning-replace-line["<small><b>Step 13</b></small><br/>Action: Replace the winch line per UMM proced..."]
free-spinning-no-damage-escal{{"<small><b>Step 14</b></small><br/>Escalation: If the line is not tangled or damaged..."}}
follow-motor-stalled-guide("<small><b>Step 15</b></small><br/>Reference: Follow the MOTOR_STALLED guide/top...")
overvoltage{{"<small><b>Step 16</b></small><br/>Escalation: Escalate to P2 Firmware Motors On Call."}}
voltage-retries-exceeded["<small><b>Step 17</b></small><br/>Action: Inspect the busbars on the affected m..."]
power-stage-degraded{"<small><b>Step 18</b></small><br/>Question: Which site type applies to this Aircr..."}
motor-overtemperature{"<small><b>Step 19</b></small><br/>Question: Which site type applies to this Aircr..."}
commercial-motor-overtemperature["<small><b>Step 20</b></small><br/>Action: For commercial operations, if this al..."]
commercial-replace-affected-motor["<small><b>Step 21</b></small><br/>Action: Replace the affected motor per the ap..."]
test-motor-overtemperature["<small><b>Step 22</b></small><br/>Telemetry: Load the Propulsion Motor Temps Baraz..."]
test-motor-overtemperature-check{"<small><b>Step 23</b></small><br/>Question: Is temperature.motor greater than o..."}
test-motor-overtemperature-replace["<small><b>Step 24</b></small><br/>Action: Replace the affected motor per the ap..."]
test-motor-overtemperature-mark-resolved["<small><b>Step 25</b></small><br/>Action: If temperature.motor is less than 2..."]
test-power-stage-degraded["<small><b>Step 26</b></small><br/>Action: Replace the affected motor per the ap..."]
other-off-nominal["<small><b>Step 27</b></small><br/>Action: Replace the affected motor per the ap..."]
follow-the-instructions-that-are-applica -->|A BUSBAR_STATUS validator h...| voltage-retries-exceeded
follow-the-instructions-that-are-applica -->|The off_nominal is MOTOR_PR...| motor-provisioned-incorrectly
follow-the-instructions-that-are-applica -->|The off_nominal is INVALID_...| invalid-encoder-calibration
follow-the-instructions-that-are-applica -->|The off_nominal is FREE_SPI...| free-spinning-dlb
follow-the-instructions-that-are-applica -->|The off_nominal is LOCK_MEC...| lock-mech-disconnected
follow-the-instructions-that-are-applica -->|The off_nominal is FREE_SPI...| free-spinning-no-dlb
follow-the-instructions-that-are-applica -->|The STALL_DETECTED or STALL...| follow-motor-stalled-guide
follow-the-instructions-that-are-applica -->|The OVERVOLTAGE off_nominal...| overvoltage
follow-the-instructions-that-are-applica -->|The VOLTAGE_RETRIES_EXCEEDE...| voltage-retries-exceeded
follow-the-instructions-that-are-applica -->|The MOTOR_OVERTEMPERATURE o...| motor-overtemperature
follow-the-instructions-that-are-applica -->|The POWER_STAGE_DEGRADED of...| power-stage-degraded
follow-the-instructions-that-are-applica -->|Other off_nominal and/or af...| other-off-nominal
lock-mech-disconnected -->|NO| lock-mech-reattach
lock-mech-disconnected -->|YES| lock-mech-build-version
lock-mech-build-version -->|EV2| lock-mech-replace-docking-fin
lock-mech-build-version -->|EV3| lock-mech-replace-dwt-flex
free-spinning-no-dlb -->|YES| free-spinning-untangle
free-spinning-no-dlb -->|NO| free-spinning-inspect-damage
free-spinning-inspect-damage -->|YES| free-spinning-replace-line
free-spinning-inspect-damage -->|NO| free-spinning-no-damage-escal
power-stage-degraded -->|Commercial Site| commercial-replace-affected-motor
power-stage-degraded -->|Test Site| test-power-stage-degraded
motor-overtemperature -->|Commercial Site| commercial-motor-overtemperature
motor-overtemperature -->|Test Site| test-motor-overtemperature
commercial-motor-overtemperature --> commercial-replace-affected-motor
test-motor-overtemperature --> test-motor-overtemperature-check
test-motor-overtemperature-check -->|Yes| test-motor-overtemperature-replace
test-motor-overtemperature-check -->|No| test-motor-overtemperature-mark-resolved
style follow-the-instructions-that-are-applica fill:#dbeafe,stroke:#3b82f6,color:#1e3a5f
style motor-provisioned-incorrectly fill:#dcfce7,stroke:#22c55e,color:#14532d
style invalid-encoder-calibration fill:#dcfce7,stroke:#22c55e,color:#14532d
style free-spinning-dlb fill:#dcfce7,stroke:#22c55e,color:#14532d
style lock-mech-disconnected fill:#dbeafe,stroke:#3b82f6,color:#1e3a5f
style lock-mech-reattach fill:#dcfce7,stroke:#22c55e,color:#14532d
style lock-mech-build-version fill:#dbeafe,stroke:#3b82f6,color:#1e3a5f
style lock-mech-replace-docking-fin fill:#dcfce7,stroke:#22c55e,color:#14532d
style lock-mech-replace-dwt-flex fill:#dcfce7,stroke:#22c55e,color:#14532d
style free-spinning-no-dlb fill:#dbeafe,stroke:#3b82f6,color:#1e3a5f
style free-spinning-untangle fill:#dcfce7,stroke:#22c55e,color:#14532d
style free-spinning-inspect-damage fill:#dbeafe,stroke:#3b82f6,color:#1e3a5f
style free-spinning-replace-line fill:#dcfce7,stroke:#22c55e,color:#14532d
style free-spinning-no-damage-escal fill:#fef3c7,stroke:#f59e0b,color:#78350f
style follow-motor-stalled-guide fill:#f3e8ff,stroke:#a855f7,color:#581c87
style overvoltage fill:#fef3c7,stroke:#f59e0b,color:#78350f
style voltage-retries-exceeded fill:#dcfce7,stroke:#22c55e,color:#14532d
style power-stage-degraded fill:#dbeafe,stroke:#3b82f6,color:#1e3a5f
style motor-overtemperature fill:#dbeafe,stroke:#3b82f6,color:#1e3a5f
style commercial-motor-overtemperature fill:#dcfce7,stroke:#22c55e,color:#14532d
style commercial-replace-affected-motor fill:#dcfce7,stroke:#22c55e,color:#14532d
style test-motor-overtemperature-check fill:#dbeafe,stroke:#3b82f6,color:#1e3a5f
style test-motor-overtemperature-replace fill:#dcfce7,stroke:#22c55e,color:#14532d
style test-motor-overtemperature-mark-resolved fill:#dcfce7,stroke:#22c55e,color:#14532d
style test-power-stage-degraded fill:#dcfce7,stroke:#22c55e,color:#14532d
style other-off-nominal fill:#dcfce7,stroke:#22c55e,color:#14532d Hover or focus a block to preview it. Select the block to keep the preview open.
1 question
Select one active OFF_NOMINAL below, complete that path, then return here and repeat for each additional OFF_NOMINAL on the affected motor.
2 action
Check for the
Perform a firmware deploy via fleetwrangler to clear this alarm.
HARDWARE_CONFIGURATION_INCORRECT from /distro_a. If that alarm is present, follow its guide, first.Perform a firmware deploy via fleetwrangler to clear this alarm.
3 action
Perform SB-2025-024 parts A and C.
The Aircraft may return to service.
The Aircraft may return to service.
4 action
Follow the DLB procedure. No need to take action on this
off_nominal. 5 question
Inspect the docking fin flex connection at the winch (not the distro-winch flex connection at the winch). Is the flex plugged in?
6 action
Reattach winch flex.
Inspect the assembly for loose screws, broken mounting lugs, or any other non-nominal conditions that could have caused the flex to become unplugged. Address damage or non-nominal conditions as needed.
Test and return to service.
Inspect the assembly for loose screws, broken mounting lugs, or any other non-nominal conditions that could have caused the flex to become unplugged. Address damage or non-nominal conditions as needed.
Test and return to service.
7 question
What build version is the aircraft?
8 action
Create a work order using Work Order Template 243. EV2: Replace Docking Fin/Winch Assembly on Aircraft
If issue persists, escalate to Powertrain On Call.
If issue persists, escalate to Powertrain On Call.
9 action
Create a work order using Work Order Template 1054. Replace the DWT flex according to EV3 Remove and Replace Distro Winch Tail Flex. If the issue persists, escalate to Powertrain On Call.
10 question
Inspect for line jumps/tangles in the line. Are there any tangles in the line?
11 action
Untangle the line, if practicable. If not practicable, remove and replace the winch line per UMM procedures:
32.3.3.b Remove Winch Spool
32.3.3.c Install Winch Spool
32.3.2.c Install Winch Line
The Aircraft may return to service.
32.3.3.b Remove Winch Spool
32.3.3.c Install Winch Spool
32.3.2.c Install Winch Line
The Aircraft may return to service.
12 question
Inspect the line for damage, refer to UMM 32.3.2.a Inspect Winch Line for guidance. Is there any damage?
13 action
Replace the winch line per UMM procedures:
32.3.3.b Remove Winch Spool
32.3.3.c Install Winch Spool
32.3.2.c Install Winch Line
The Aircraft may return to service.
32.3.3.b Remove Winch Spool
32.3.3.c Install Winch Spool
32.3.2.c Install Winch Line
The Aircraft may return to service.
14 escalation
If the line is not tangled or damaged, escalate to P2 Firmware Motors On Call.
15 reference
Follow the MOTOR_STALLED guide.
16 escalation
Escalate to P2 Firmware Motors On Call.
17 action
Inspect the busbars on the affected motors for loose bolts or damage. Refer to UMM 20.2.4.c Inspect Busbar for details.
Repair or replace the busbars, clips, bolts, and mounts as needed.
The Aircraft may return to service.
Repair or replace the busbars, clips, bolts, and mounts as needed.
The Aircraft may return to service.
18 question
Which site type applies to this Aircraft?
19 question
Which site type applies to this Aircraft?
20 action
For commercial operations, if this alarm is raised for hover or mixed motor overtemperature, replace the affected motor.
21 action
Replace the affected motor per the applicable UMM install and remove instructions.
Return the LRU to the Aviary.
The Aircraft may return to service.
Return the LRU to the Aviary.
The Aircraft may return to service.
22 telemetry
Load the Propulsion Motor Temps Baraza template for the mission. Use it to identify
temperature.motor. Enter the mission identifier above to load the plot.
23 question
Is
temperature.motor greater than or equal to 220C? 24 action
Replace the affected motor per the applicable UMM install and remove instructions.
Return the LRU to the Aviary.
The Aircraft may return to service.
Return the LRU to the Aviary.
The Aircraft may return to service.
25 action
If
temperature.motor is less than 220C, mark the discrepancy for this alarm as resolved and power cycle the Aircraft. 26 action
Replace the affected motor per the applicable UMM install and remove instructions.
Return the LRU to the Aviary.
The Aircraft may return to service.
Return the LRU to the Aviary.
The Aircraft may return to service.
27 action
Replace the affected motor per the applicable UMM install and remove instructions.
Return the LRU to the Aviary.
The Aircraft may return to service.
Return the LRU to the Aviary.
The Aircraft may return to service.
Resolution note
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