Textron Aviation Cessna 172S NAV III Skyhawk SP, Information Manual

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SECTION 7 CESSNA
AIRPLANE AND SYSTEM DESCRIPTION MODEL 172S NAV III
KAP 140 AUTOPILOT
U.S.
ELECTRICAL SYSTEM
(Continued)
EXTERNAL POWER RECEPTACLE
A external power receptacle is integral to the power distribution module
and allows the use of an external power source for cold weather
starting or for lengthy maintenance work on electrical and avionics
equipment. The receptacle is located on the left side of the cowl near
the firewall. Access to the receptacle is gained by opening the
receptacle door.
NOTE
Set the AVIONICS switches BUS 1 and BUS 2 to OFF if no
avionics are required. If maintenance on the avionics
equipment is required, a 28 VDC regulated and filtered
external power source must be provided to prevent damage
to the avionics equipment from transient voltages. Set
AVIONICS switches BUS 1 and BUS 2 to OFF before
starting the engine.
The following check should be made whenever the engine has been
started using external power (after disconnecting the external power
source).
1. MASTER Switch (ALT and BAT) - OFF
2. TAXI and LAND Light Switches - ON
3. Throttle Control - REDUCE TO IDLE
4. MASTER Switch (ALT and BAT) - ON (with taxi and landing lights
turned on)
5. Throttle Control - INCREASE (to approximately 1500 RPM)
6. Main Battery (M BATT) Ammeter - CHECK (Battery charging,
Amps Positive)
7. LOW VOLTS Annunciator - CHECK (Verify annunciator is not
shown)
WARNING
IF M BATT AMMETER DOES NOT SHOW POSITIVE
CHARGE (+ AMPS), OR LOW VOLTS ANNUNCIATOR
DOES NOT GO OFF, REMOVE THE BATTERY FROM
THE AIRPLANE AND SERVICE OR REPLACE THE
BATTERY BEFORE FLIGHT.
172SPHAUS-05
7-58
For
Training
Purposes
Only