Astro SB006 – Required Astro Firmware Update

• Astro Base – Sku: 950-00108-01 and 950-00108
• Astro Map – Sku: 950-00106-01 and 950-00106

INTRODUCTION

This Service Bulletin SB006 is issued to recommend all Astro aircraft be updated to Firmware v1.1.18 immediately to resolve the issues shared in Service Bulletin SB005. The previous Service Bulletin SB005 grounded all Astro aircraft. This order is now superseded – Astro Flight operations can safely resume only if the aircraft is flying v1.1.18 or later.

BACKGROUND

SB005 grounded the Astro fleet due to an unknown issue that resulted in a customer crash. The root cause of the customer crash has been determined, fixes implemented in new firmware, and firmware testing completed and passed. The crash root cause was identified to be an electrical hardware failure (onboard SD card system) which exposed software bugs that eventually caused the Astro flight controller to lock up in flight and lose control of the aircraft.

Firmware version v1.1.14 and all previous firmware versions are permanently grounded. It is believed that all previous Astro firmware versions are affected. Astro vehicles can safely resume Astro flight operations only if they have updated their aircraft to v1.1.18 or later.

Additional Software Release notes for v1.1.18 are linked here

Download firmware version v1.1.18 at the link here. Directions for how to update Astro firmware are located in our Flight Manual 

DISCUSSION

Details of root cause investigation:

• Issue: On February 7th 2023, a customer flying Astro with release firmware version 1.1.14 had an in-flight software failure, resulting in a crash. 
• Root Cause:
  • An electrical hardware failure (onboard SD card system) resulted in intermittent communications on an SD card pin
  • This intermittent connection exposed the first bug in the low-level hardware driver which, if there was any interruption to the SD card connection, would cause the driver to enter into a busy loop. 
  • The second issue was a weakness in the task prioritization code, which prioritized the SD card logging task over other critical functions, such as flight controls, when the system CPU was overloaded. 
  • This resulted in the SD card logging task getting stuck in a busy loop, which prevented all other operations and ultimately caused the aircraft to crash.
• Solution:
  • We have now addressed both of the issues in the software and undergone a thorough code review. The SD card logging reprioritization feature has been removed to ensure that logging operations will never take priority over flight controls. Additionally, the bug in the hardware driver has been fixed to prevent any future lock-ups.  
  • These fixes allow the software to gracefully manage any SD card failures and allow the aircraft to safely continue operation. 
• Validation
  • We have performed hotfix specific test plans for the new changes, executed our full engineering software validation testing, and performed over 50 hours of functional flight time across 10+ pilots and Astros.

RECOMMENDATION

1. Update all Astro aircraft to firmware v1.1.18. Do not fly any Astro’s that are on v1.1.14 or older firmware version.
2. Perform a vehicle compass calibration after firmware update.
3. Resume safe flight operations with Astro only if the aircraft is on v1.1.18