Electrical And Related System; Electrical System - Lancair Columbia 400 Information Manual

Section 7
Columbia 400 (LC41-550FG) Description of the Airplane and Systems
ELECTRICAL AND RELATED SYSTEMS

ELECTRICAL SYSTEM

General Description – The electrical system in this aircraft consists of two independent buses,
which are referred to as the left bus and right bus. Two 60-amp (continuous output) alternators
provide charging power for the two 14 volt, lead-acid batteries, as well as system power. The
batteries will also provide additional power in the event of an over demand situation where the
requirements on the system are greater than what can be provided by the alternator. The left and
right buses in turn feed the avionics and essential buses. Please refer to Figure 7 - 19 for a
diagram of the electrical system.
Five current limiters protect the alternators and bus outputs. In addition, the left and right buses
are physically isolated inside a covered area mounted to the firewall. Left and right bus controls,
grounds, and outputs are routed through separate holes, connectors, and cable runs so any failure
on one bus will not affect the operation of the other bus.
Control of the buses is via the master switch panel located on the lower left portion of the
instrument panel. There is also a crosstie switch on this panel, which will restore power in the
event of failure of the right or left systems. For example, if the alternator or some other
component on the left side should fail, the crosstie switch will restore power to the electrical
items on the left bus by connecting the left bus to the right bus.
As its name may suggest, power to the essential bus is never affected, provided power from at
least one bus (left or right) is available. The essential bus is diode fed, i.e., current will only flow
in one direction, from both the right bus and the left bus allowing the essential equipment to have
two sources of power. A summary of the buses and related circuit breaker protection is shown in
Figure 7 - 17.
Avionics Bus – The avionics bus provides power to the Audio/Voice, GPS 1, GPS 2, Nav/Com
1, Com 2, Transponder/Encoder/Equipment Fan, Traffic, Autopilot, MFD, and Weather. These
devices are protected by their own circuit breakers. The circuit breaker ratings are: Audio/Voice
(5 amp), GPS 1 (5 amp), GPS 2 (5 amp), Nav/Com 1 (10 amp), Com 2 (10 amp), and
Transponder/Encoder/Equipment Fan (5 amp), Traffic (4 amp), Autopilot (5 amp), MFD (10
amp), Weather (5 amp).
Left Bus – The left bus provides power for the Aileron Trim, Pitot Heat, Engine Instruments,
Oxygen, Position Lights, Landing Light, Left Voltage Regulator, Clock, Cabin Fan, and PFD
Power. Most of these devices are individually protected with circuit breakers rated as follows:
Aileron Trim (1 amp), Pitot Heat (10 amp), Engine Instruments (3 amp), Oxygen (3 amp),
Position Lights (10 amp), Landing Light (4 amp), Left Voltage Regulator (5 amp), and
Clock/Fan (7.5 amp), PFD Power (10 amp).
Right Bus – The right bus provides power for the Strobe Lights, Taxi Light, Right Voltage
Regulator, Door Seal, Auxiliary Power Unit, PFD Power, and Elevator Trim. Most of these
devices are individually protected with circuit breakers rated as follows: Strobe Lights (10 amp),
Taxi Light (4 amp), Right Voltage Regulator (5 amp), Door Seal/Power Point (5 amp), PFD
Power (10 amp), and Elevator Trim (1 amp).
Initial Issue of Manual: November 10, 2004 RC050002
Latest Revision Level/Date: -/11-10-2004 7-57