This change allows the Captains Pitot Heater to remain powered in the event of a main and essential electric
power failure. Post this change, during normal operation the Captains Pitot Heater is powered from the 115V
AC Transfer Bus but automatically switches to the 115V AC Standby Bus in the event of a main and essential
electric power failure.
This change may only be performed on aircraft equipped with dual (two) standby batteries providing a
minimum of 60 minutes of standby electrical power.