Technical data

13773-001
24-30
Page 4 30 Nov 2000
F. Volt and Ampere Meter
A combination Volt and Ampere meter is mounted on the right instrument panel immediately outboard
of the oil temperature and pressure gage. The AMP pointer sweeps a scale from -60 to +60 amps with
zero at the 9 o'clock position. The ammeter will indicate the current generation provided by Alternator
1, Alternator 2, and the charge or discharge status of battery 1.
The VOLT pointer sweeps a scale from 16 to 32 volts. The voltage indication for the Volt / Ampere
Meter is measured off the annunciator circuit breaker which is on the Essential Bus. The voltage
required to operate the internal meter lighting is supplied through the 2-amp instrument lights circuit
breaker which is on Main Bus 1. Main Bus voltage (measured at the engine instrument circuit breaker)
is displayed on the clock voltmeter for reference.
G. Ammeter Select Switch
An ammeter select switch is located on the right instrument panel and is labeled distinctly. The amme-
ter select switch controls which output reading the ammeter will display the voltage from ALT 1, ALT 2
or the BAT 1 or BAT 2. The ammeter will also display the state of charge or discharge either battery is
in. The amps indication is derived from a current transducer located in the electrical system MCU.
When the engine is operating and the BAT 1 switch is turned on, the ammeter indicates the charging
rate applied to battery 1. Due to the inability of the alternators to dissipate current, the alternator
ammeter indications are positive only.
H. Battery 1
Battery 1 is a 24-volt, 12-cell,10-ampere hour, lead-acid aviation-grade type battery with non-spill vent
caps. The battery is mounted in the engine compartment and has a top vent with an acid-resistant
tube. The tube discharges out the bottom of the engine cowling, preventing the build up of dangerous
or explosive gasses within the engine cowl.
The battery is used for engine starting and can also be used as an emergency power source in the
event Battery 2 fails or in the event of either alternator failure. Battery 1 provides all the electrical
power for starting the aircraft. Battery 1 also supplies the electrical power to the landing light in the
event Alternator 1 fails. Battery 1 is independently controlled by the BAT 1 switch, located in the pilot’s
bolster panel. The BAT 1 switch energizes a relay in the MCU which will connect BAT 1 to the Main
Distribution Bus.
I. Battery 2
Battery 2 consists of two 12-volt, 6-cell, 7-amp-hour batteries connected in series to provide 28-VDC to
the Essential Bus. Battery 2 is independently controlled by using the BAT 2 switch, located in the pilot’s
bolster panel. The BAT 2 switch energizes a relay located just aft of bulkhead 222 in the MCU which
will connect BAT 2 to the Essential Bus. The electrical power from BAT 2 reaches the Essential Bus
through the circuit breaker panel. Battery 2 is mounted directly behind bulkhead 222 in an acid resis-
tant battery container.
Battery 2 is primarily used to power the Essential Bus. The Essential Bus delivers electrical power to
the annunciator lights, turn coordinator, attitude indicator, horizontal situation indicator (HSI), stall
warning system, and alternator 2.
Failure of the BAT 1 will not affect the ability of BAT 2 to provide necessary power to the Essential Bus.
Because of diode protection, a failure or malfunction of the BAT 1 will not affect BAT 2 or either alterna-
tor output.
Note: Prior to engine start-up, the pilot must activate only the BAT 2 switch to verify that BAT 2
properly energizes the electrical loads powered by the Essential Bus and that BAT 2 has
proper voltage. The voltage reading must be taken from the combination Volt and
Ampere meter mounted on the right instrument panel.