Date Released: April 11th, 2022
Subject: High power radio interference affecting Astro functionality
Effectivity: Effective immediately
Required Action: Do not use high power / low frequency radio transmitters mounted to Astro aircraft
INTRODUCTION
This Service Bulletin is being issued to alert all Astro operators that Freefly has found an interference susceptibility in Astro when using high power/low frequency radio transmitters on the aircraft.
While these transmitters are not part of the Astro Base or Astro Map product, the user could attach these products to the Astro for custom integration. The use of these modules on Astro may cause interference with the motor drives and cause instability to the motors that could lead to a tip-over during takeoff or possibly to a crash. Due to this risk, Freefly recommends that operators not use or install these types of radio transmitters on Astro.
BACKGROUND
Astro motor drives are susceptible to radio interference from high power radios operating below 2 GHz or utilizing high power burst transmissions in certain configurations and this interference can cause the motor drive to lose sync with the motor. We are working to better understand the issue to communicate customer actions, and drive near and long term improvements.
During extended testing by the engineering team at Freefly we were mounting FRX pro in various spots on the aircraft for real time data logging downlink and discovered that some mounting positions introduce interference that can introduce noise into the motor drives. In a few specific mounting locations shown below and with very high power transmitters we can cause the motor drive to fail its startup routine. Due to this discovery, if the operator chooses to accept this increased risk, we suggest that any custom radio is mounted underneath the Astro via the smart dovetail and to bench test the install location with props removed. If you have any questions about your installation we are here to help, just contact us.
Although we haven’t received any reports of any related issues from current Astro users, Freefly has initiated an internal investigation to characterize the problem in more detail, and to come up with recommendations and solutions.
DISCUSSION
Some key points to convey regarding this issue:
What we know from our investigation:
Figure 1. Example of an unacceptable radio mounting location that has direct line between antenna and the plastic tub on side of chassis
RECOMMENDATION
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