If aircraft main electrical power is interrupted for any reason
during checkout, EGI switch shall be rotated to OFF immediately. Failure to position EGI switch to OFF
results in discharging of INS battery.
• Upon restoration of aircraft main electrical power, check for INS battery warning (MFL EGI 012),
perform appropriate fault isolation procedures,
if required,
and allow additional aircraft main electrical power on line to recharge INS battery.
Failure to comply may result in EGI memory loss and additional discharging of INS battery.
• After EGI switch OFF position is selected, EGI requires 30 seconds to perform power down memory update.
Restarting EGI or removing aircraft main electrical power within 30 seconds causes an incomplete memory update and subsequent degraded navigation performance.