Technical data

13773-001
24-00
Page 1
ELECTRICAL POWER
1. GENERAL
The information in this chapter covers DC Generation, External Power, and Electrical Load Distribution.
This airplane is equipped with a 28-volt direct-current (VDC) electrical system. Two alternators and two
batteries are used to ensure sufficient electrical power. Electrical power is supplied to the essential bus
from both batteries and both alternators. The electrical system provides automatic switching from either
battery or alternator to the essential bus in the event of an electrical system failure by the opposing alterna-
tor or battery. The electrical system provides uninterrupted power for avionics, flight instruments, lighting
and other electrically operated and controlled systems during normal operation.
The generation system consists of a 24-volt, 10-amp-hour battery, two 12-volt 7-amp-hour batteries (con-
nected in series for 24-volts), 60-amp (rated at 58-amps) engine-driven alternator, 20-amp engine-driven
alternator, voltage regulator, and an over-voltage protection system. The bolster panel contains the pilot
switches for operating both batteries (BAT 1 and BAT 2) and both alternators (ALT 1 and ALT 2). The
switches are mounted adjoining so that a pilot can control all four switches with a single hand.
Power generated from the alternators is fed into the Master Control Unit (MCU). The MCU regulates and
distributes the power to the batteries and the system loads. Each alternator provides constant charging
current for its corresponding battery and primary power to the aircraft electrical system during normal sys-
tem operation.
2. TROUBLESHOOTING
Troubleshooting Power Generation System
Trouble Probable Cause Remedy
No Alternator Output
(Voltmeter Indicates 24 VDC or
less and the ammeter indicates a
discharge when the corresponding
Bat switch is in “on” position)
Loose alternator wire connection Tighten connector
Alternator switch off Turn on corresponding alternator
switch
Defective alternator Replace alternator
Circuit breaker activated (open)
Faulty voltage regulator
Reset circuit breaker and trouble-
shoot circuit
Low engine RPM Increase engine RPM
Alternator output is low Loose alternator wire connection Tighten corresponding connector
Faulty rectifier Replace corresponding alternator
Faulty MCU Replace MCU
Low engine RPM Increase engine RPM
No battery output Poor battery connections Clean and tighten connections
Failed battery Replace corresponding battery
Battery water usage high (Battery
1)
Alternator output high, faulty volt-
age regulator
Replace MCU
30 Nov 2000