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If the Aperture Cover drives fault, the GIS will not allow the M1 Cover to open close the light path, preventing M1 from opening and will try to force the Aperture Cover to close. UnfortunatelyOccasionally, occasion the Aperture Cover drives will fault at the end of their opening motion with a standstill fault.
Because the light path logic has been tripped, the GIS checks for the both the M1 cover and aperture cover to close. Due to the drive fault, the aperture will fail to close. This causes a GIS Fault. To clear this fault both the aperture cover and M1 cover must be closed first. This results in a catch-22 of opening the aperture cover, drive fault, and then GIS fault, which will prevent progress as long as the drive faults continue.
To get around this we need to open the aperture cover and reset the drives. However, the logic will close the light path if this happens, which will lead to an aperture cover timeout fault. So, we temporarily force the ready bit on. This will give us time to reset the drives. Then we can disable the bypass and continue normally.
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