Piper Navajo Chieftain PA-31-350 Service Manual page 618

NAVAJO CHIEFTAIN SERVICE MANUAL
is protected by the radio accessories circuit breaker. On aircraft with Serial No. 31-8052001 and up, all four
rheostats are located between the two fuel quantity guages in the overhead panel. These include the pilot's and
co-pilot's (optional) lights dimmer and the overhead panel lights dimmer. A single circuit breaker protects
these circuits. The Avionics lights dimmer is located here also and is protected by its own circuit breaker.
e. Three cabin lights, one on each side of the instrument panel are controlled by switches adjacent to the
lights. There are seven cabin reading lights located above each passenger seat and controlled by switches
adjacent to the lights. Also. two door ajar indicator lights are located in the overhead panel (Serial Nos. 31-
7305001 to 7752193) or in the annunciator panel (Serial Nos. 31-7852001 and up) and are controlled by
switches located at the latching mechanisms of the cabin and baggage doors. As optional equipment a "No
Smoking" and "Fasten Your Seat Belts" sign can be installed with their switches located on the overhead
panel. An optional reminder chime may also be installed on later models. These circuits are protected by a
single circuit breaker.
f. Independent of the master switch are dome. entrance and baggage compartment lights. The divider
lights are also on this circuit on later models. This circuit is protected by a fuse on the master contactor next to
the battery. The baggage compartment light is controlled by a switch located in the frame of the baggage door.
The dome and entrance lights are controlled by two-way switches, with one located just inside the entrance
door and one in the pilot's switch panel placarded "Overhead Lights". The divider lights are controlled by
switches located in the appropriate divider.
g. An annunciator panel is incorporated in aircraft with Serial Nos. 31-7852001 and up. This panel
monitors various functions of the electrical system and contains warning lights grouped together and
extending across the upper center of the instrument panel. A press-to-test switch, located to the left of the
panel, illuminates all warning lights and must be held for at least 3 seconds in order for all lights to illuminate.
A dimmer-ro the right of the panel controls intensity of the lights and a circuit breaker located in the left side
panel controls power to the annunciator panel.
The gear. oil temperature, cylinder head temperature and fuel quantity indicators and their associated
sender units are protected by a single circuit breaker. The left and right turn indicators are each connected
directiv to the main distribution bus through its own circuit breaker.
The stall warning indicator consists of a horn and a flashing light. The light is located in the instrument
panel evebrow directly in front of the pilot and is connected to the lift detector switch located in the right wing.
outboard of the engine nacelle. On airplanes with a stall warning time delay, the delay unit is mounted to the
channel above the access panel at Sta. 64.5. This time delay unit assures a horn sound when left detector switch
closes and for four seconds after detector switch opens. On airplanes with Serial Nos. 31-8052001 and up. a
heated lift detector is available with the de-ice group. This provides heat for both the vane and the plate to
assure proper operation during icing conditions.
The trim and cowl flap indicator circuit consists of a "clamped" power source (a diode and resistor
arrangement connected to the circuit breaker to clamp the output voltage to the circuit at 20-volts DC),
voltmeters for indicators and rheostats located on the appropriate mechanisms to sense their positions. A
synchroscope kit is offered as optional equipment. Both the sender circuits are protected by the same circuit
breaker.
The heater switch located to the right of the control pedestal beneath the flap switch, is placarded "FAN".
"OFF", and "HEAT". In the fan position, only the ventilating blower functions and in the heat position all
heater systems operate. In flight, the ventilating fan motor is disabled through the gear safety switch by
removing its ground. On models with Serial Nos. 31-8052001 and up, the heater incorporates a reset in flight
feature in case of overheating. An "OVERTEMP" warning light is also provided in the annunciator panel.
A ground vent fan and beverage unit are incorporated on the aircraft as optional equipment. The ground
vent fan being controlled by a switch in the overhead switch panel. The circuits are protected by separate
circuit breakers on earlier models, by a single circuit breaker-on models beginning with Serial No. 31-7752001.
and again by separate circuit breakers on later models.
Reissued: 9/23/80
ELECTRICAL SYSTEM
3C16