SB002 Alta X – Intermittent Motor Start Failure – Update (2/17/20)
Date Released: Feb 17 2020
Effectivity: All Alta X
This service bulletin is being issued to alert all Alta X pilots of an intermittent failure of Motors to start spinning upon initial startup.
Freefly has received ~5 reports of Motor 1 not starting properly in the field. Freefly has completed the first stage of our investigation into the issues. We developed an automated test that power cycles the Alta X and initiates a startup command. Over the course of 8,396 test cycles we detected 19 instances in which a motor did not start properly. We have traced the condition back to the Motor Drive and have observed that occasionally the motor drive will falsely signal a ‘phase error’ failure. We do not understand the conditions for this error to occur and are working to understand the root cause.
Some key points to convey regarding this issue:
- We have received no report of motor failure in flight, the failure mode appears to only exist upon startup. Once a motor is spinning there is no evidence that the issue can occur.
- We observed various booms (1-4) exhibiting this behaviour.
- A reboot of the machine has cleared the issue so that normal operation can continue.
- Throttling up the Alta X without a motor starting can cause a tip over.
- Always visually confirm all motors are spinning prior to liftoff
- Always perform an attitude control flight check prior to takeoff (demonstrated here)
- In case of a motor failure to start, disconnect Alta X flight batteries and reboot machine
- Please file a ticket with customer support so we can investigate and track this issue
See attached PDF for full details
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