Cessna 1971 Super Skymaster Owner's Manual page 11

seconds duration. Then retard the throttle, turn off the auxiliary fuel
pump, and use the starter to turn the engine over until a start is obtained.
In normal fuel system operations, the "LEFT MAIN" auxiliary pump
supplies the front engine, and the "RIGHT MAIN" auxiliary pump supplies
the rear engine. For crossfeeding purposes, use the "RIGHT MAIN" aux ­
1l1ary pump for the front engine, and the "LEFT MAIN" auxiliary pump
for the rear engine.
FUEL QUANTITY INDICATORS AND OPTIONAL AUXILIARY FUEL
INDICATOR LIGHTS.
Two fuel quantity indicators in the engine instrument cluster indicate
fuel level in the main or optional auxiliary tanks, depending on fuel selec ­
tor valve handle pOSition. With the selector valves in the "MAIN" position,
the indicators will show fuel quantity, in gallons and pounds, in the main
tanks. When an optional auxiliary system is installed, and the selector
valves are placed in the "AUXILIARY" pOSition, two amber lights marked
"AUX FUEL ON " and located above the instrument cluster will illuminate
and fuel indicators will show auxiliary fuel quantity.
FUEL STRAINER AND TANK SUMP DRAINS.
Refer to servicing procedures in Section V.
ELECTRICAL SYSTEM.
Electrical energy is supplied by a 28-volt, direct- current system
powered by two engine-driven alternators (see figure 2-3). Electrical
energy is stored in a 24-volt battery located in the lower left portion of
the front engine compartment. Power is supplied to all electrical cir­
cuits through a split bus bar, one section containing electronic system
circuits and the other section containing lighting and general electrical
system circuits.
The entire bus is on at all times except when either an external power
source is connected or the ignition/starter switches are turned to the
"START" position; then a split bus contactor is automatically activated to
remove power from the electronics section of the bus. This isolates the
electronic circuits and prevents harmful transient voltage from damaging
the transistors in the electronics equipment.
MASTER
SWITCH.
The rocker-type master switch provides a means of Isolating the air­
craft bus from the power supply system by controlling the battery con­
tactor and both alternator field circuits. The alternators will not function
with the master switch turned off.
When using the battery or an external power source for lengthy main ­
tenance checks on the electrical system, the master switch should be
turned on. (Refer to Section VIT, under GROUND SERVICE PLUG RECEP ­
TACLE, for additional operating details concerning use of an external
power source.)
ALTERNATOR
SWITCHES.
Both alternator switches are combined in a split rocker-type switch
labeled "F. ALT R." The alternator switch controls both front and rear
engine alternators and permits switching the front or rear alternator off
in the event of an alternator, alternator circuit or engine failure.
If
an
alternator is turned off, operation should be continued on the functioning
alternator, using only necessary electrical equipment.
VOLTAGE REGULATOR SELECTOR SWITCH.
The airplane contains two voltage regulators. Both voltage regulators
are controlled
by
a single rocker-type switch labeled "REG," "1" and "2"
located adjacent to alternator switch. Each voltage regulator will control
output of both alternators, leaving the other regulator available on a stand ­
by
basis. Either regulator can be placed in operation by switching rocker­
type selector switch to the "1" (up) position or the "2" (down) position.
ALTERNATOR RESTART
SWITCH.
The alternator restart system is operated by a momentary push­
2-5
2-4