Astro SB001 – Propeller Mount Mandatory Replacement

Astro SB001 – Propeller Mount Mandatory Replacement
Date Released: September 30th 2021
Subject: Propeller Mount Replacement
Effectivity: Effective immediately and implemented into design of record
Required Action: Replace Propeller Assemblies with Freefly provided upgraded hardware


This service bulletin is being issued to operators who own an Astro with the following serial numbers shipped before 10/1/2021. This bulletin requires mandatory action to remove and replace propeller mount hardware:

109AFDAB 1090EBB4 109DB04C 1096779D 1091B94A
109CDDFE 109079BF 109D3DA6 109D3C14 109F2237


During extended testing, the engineering team has discovered that the mount assembly used on the affected aircraft holding the propellers to the motor can fail if the parts have been previously damaged and have a high number of lifetime flight hours. Since these parts must last the lifetime of an aircraft, the design has been upgraded. Any Astro not listed here is unaffected by this bulletin.

Scope: Any units that shipped after 10/1/21 have the latest version of parts and no action is required.


Freefly has flown over 500 hours with the original propeller mount design. After seeing a single failure of this part in testing, we feel that that design should be more robust to ensure that even with damage the part will outlast the aircraft’s lifetime. As a precautionary measure, we are limiting the lifetime of the current design to 100 flight hours and also requiring a replacement of these parts for any units in the field.

Additional documentation

If you purchased replacement propeller sets, these will be replaced as well. Please discard old assemblies.


  1. Action: Immediate assembly replacement
    1. Freefly will contact each customer with affected unit serial numbers and send the customer a replacement set of propeller assemblies to install on each aircraft (as well as replacements for spare prop kits)
    2. Customer will follow the Assembly Instructions for removing and replacing the propeller assemblies
    3. The old propeller assemblies must be discarded once they are removed from the aircraft.


Downloadable PDFs

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