We are issuing a safety advisory affecting a small number of GliderKeeper units. During a firmware update, affected units can momentarily produce an unexpected throttle output which, if the ESC is connected and a propeller is fitted, could cause a brief, sudden propeller movement. Only a few cases have been reported, but because a moving propeller can cause injury or damage, please read this before your next firmware update.
Before updating a unit that runs an affected firmware, power it from an external supply and either disconnect the aircraft's ESC or remove the propeller.
Affected firmware
- GliderKeeper / GliderKeeper Pico running FAI F or FAI S 1.32 / 3.32, on GliderKeeper v2 or GliderKeeper Pico hardware.
- Universal firmware (GKU) FAI S / FAI F 5.41, on all platforms.
There is no clear correlation with any ESC brand or model; it is believed to be related to an electrical power-supply transient. Only a few cases have been reported.
What happens
These latest-generation firmwares keep a steady 900 µs throttle output pulse at all times. During a firmware update, an affected unit may reset. At the instant of the reset, that signal changes from the 900 µs PWM pulse to a high-impedance state for a blink of time. In some installations, if the ESC is connected, this can cause a sudden propeller movement for less than half a second. With a propeller fitted, that movement could potentially cause damage or injury.
What to do now
Until you have installed the permanent fix, when updating a unit that runs one of the affected firmwares:
- Power the GliderKeeper from an external power supply, and
- disconnect the aircraft's ESC before updating, or
- remove the propeller from the aircraft's power train.
The permanent fix
Update to firmware 5.42. This firmware will be available soon, once the FAI has granted its homologation. Perform this particular update with the precautions above (external power, ESC disconnected or propeller removed), since the unit is still running an affected firmware while it updates.
From then on you are covered. With 5.42 in control, the firmware drives the throttle signal to a logic zero immediately on entering Wi-Fi mode or when a BLE update starts, removing the throttle pulse before any reset could occur. On later updates the unit no longer resets in this way; instead the display shows a prompt asking you to disconnect the power train and reconnect it afterwards, eliminating this potentially unsafe condition entirely.