Electrical System - MAULE Orion M-7-260C Maintenance Manual

The electrical system is a 14 or 28 volt, 50 amp, direct current, single wire circuit using
the airplane structure as a ground return to the battery. All wiring in the airplane is fabricated
into harnesses which are groups of related wires tied together. Most of the harnesses originate
at circuit breakers on the main bus (center of instrument panel) and terminate at the load (light,
pump motor, etc.) Wiring diagrams are shown at the end of this manual.
CAUTION: Addition(s) of electrical equipment must not cause the total load to exceed 50 am-
peres. The total rated alternator capacity is a nominal 63 amperes at cruise rpm. Paragraph 4-
26(d) of FAA AC 43.13-1A limits the total continuous load to 80% of the total rated capacity, or
50 amperes. A 50 amp circuit breaker is installed in aircraft.
BATTERY:
A lead plate type storage battery rated at 12 or 24 volts is installed in the battery frame as-
sembly behind rear cabin bulkhead. The battery supplies current for the airplane electrical sys-
tem when the master switch is in the "ON" position only. A heavy-duty battery solenoid switch is
installed next to the battery and is controlled from the Instrument panel by the battery switch.
The battery is the sealed type with the base being integrally vented. Tubes attached to the
case vent the battery to the fuselage bottom. Battery caps should be kept tight to prevent elec-
trolyte spillage. If spillage does occur, the affected area should be cleaned with a liberal applica-
tion of an acid neutralizing solution such as baking soda and water.
This battery is considered fully charged at a hydrometer specific gravity reading of 1.265.
A low charge would be 1.225 or lower. Operating with a low charge will shorten the life of the
battery and can be prevented by recharging or operating with the electrical equipment turned off
until the battery has been sufficiently recharged.
ALTERNATOR AND ALTERNATOR CONTROL SYSTEM
To protect the alternator and battery from an overcharge, the voltage regulator should be
checked for a charging voltage of 13.7 to a maximum of 14.0 volts with the engine at rpm of
1000 or above.
Overvoltage protection is incorporated into the alternator control unit which will latch off regulator
output after an overvoltage event. Reset of latch off caused by either over voltage or shorted
output is accomplished by momentary turn off of supply voltage, i.e., push ALT switch OFF then
ON.
Battery charging is monitored by reference to the ammeter located in the instrument panel
on the right side of the engine instrument cluster. Should the ammeter indicate a minus deflec-
tion when engine is above 1000 rpm and/or red "ALTERNATOR OFF WARNING" light is illumi-
nated, push ALT the switch OFF then ON. Repeat two times as necessary to reset. If system
will not reset, investigate electrical malfunction as operation will be on the battery only.
Rev. C
MAULE AEROSPACE TECHNOLOGY, INC.
MAINTENANCE MANUAL
M-7-260C
FOR

ELECTRICAL SYSTEM

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