AHRS Battery Power

CHAPTER SIX

STUDENT GUIDE FOR T-1A AIRCRAFT SYSTEMS

indicates the standby battery is the only source powering the standby bus, and the ARM indicator

will extinguish.

AHRS Battery Power

A 24 VDC lead-acid AHRS auxiliary battery

Two BATTERY test switches and an annunciator

The AHRS auxiliary battery (mounted in the avionics rack) provides power to either/or both

AHRS computers. If either the left load bus and/or right load bus power fails or if either load

bus power falls below a preset limit, it is capable of supplying 24 VDC input power to both the

AHRS computers for up to ten minutes.

DC Power Distribution

Primary Power Distribution

DC power is distributed from the left and right main buses to their respective load buses through

two identical sets of three feeder lines, which are Remote Controlled Circuit Breaker (RCCB)

protected. In each set, only two feeder lines are active, while the third is considered a standby

feeder. The third feeder becomes active and the L BUS FDR FAIL or R BUS FDR FAIL

annunciator illuminates if either or both of the active feeder RCCBs trip.

DC Standby Power Distribution

The DC standby power distribution subsystem connects the standby battery to the standby bus.

The emergency bus supplies a charge current to the standby battery.

Emergency Power Distribution

The emergency power subsystem supplies DC power to safety of flight subsystems under

emergency conditions. The emergency bus normally receives power from the aircraft generator

through the emergency bus power relay, which is connected to the emergency bus feeder RCCB.

DC Electrical Controls and Indicators

DC Ammeters

The ammeters placarded LH AMPS and RH AMPS are located on the overhead switch panel.

The meters display the current supplied by the right and left generators. The ammeters scale

range is from 0 to 500 ampere.

6-4

ELECTRICAL POWER SYSTEMS