2.
Installation of the instruments will be the reverse of removal. After the installation is completed check all components for security and clearance of the control column.
ANNUNCIATOR PANEL.
The annunciator panel, located near the top center of the instrument panel, is a series of lights which warns of malfunctions in critical systems and circuits necessary for safe operation. A malfunction is indicated by the illumination of an individual warning light. There are five lights (ALT, OIL, VAC, LO BUS, HTR OVERTEMP).
The yellow VAC warning light is controlled by a vacuum sensor switch located at the firewall and is attached to the vacuum regulator. The sensor switch will activate when the differential pressure is below 4+ .25 in. hg.
The yellow OIL warning light is controlled by an oil pressure sensor switch incorporated in the oil line to the oil pressure gauge and is located at the firewall. The sensor switch will activate when the oil pressure is (15 psi) and decreasing.
The yellow ALT warning light is illuminated by current flowing from the bus bar to the alternator circuit. This condition exists when the alternator is not operating properly and the output is zero. During normal operation, the alternator warning circuit is also supplied with power from the top diode terminal. This current flows to two resistors and diodes creating a no-flow condition and extinguishing the ALT light.
The red LO BUS light illuminates when bus voltage (14 volts) drops to battery voltage (approx. 12 volts).
The red HTR OVERTEMP light activates when the overheat limit switch energizes, indicating an overtemperature condition in the heater vent jacket and rendering the heater inoperative.
With the battery master switch on, a press-to-test button located adjacent to the annunciator lights will check the operation of the lights.
TROUBLESHOOTING ANNUNCIATOR.
Chart 3901 depicts commonly experienced problems, their likely causes and possibly solutions. For further information contact the nearest Piper Distributor and ask for the Distribution Service Adminstrator (DSA).
39-10-00 Page 39-5 Issued: April 1, 1997
CHART 3901. TROUBLESHOOTING (ANNUNCIATOR PANEL)
Trouble Cause Remedy
All lights fail to operate. No current. Check all wire segments, connections and the receptacle at the side of the annunciator panel.
All the warning lights fail to extinguish after engine is running. Test switch grounded out. Check terminals and replace switch if necessary.
OIL or VAC warning light fails to extinguish. Sensor activates at too high a setting. Sensor terminals bridged. Defective sensor. Replace. Remove material between terminals. Replace.
OIL or VAC warning light fails to operate. Lamp burned out. Sensor activates at too low a setting. Defective sensor. Replace. Replace. Replace.
ALT warning light fails to operate. Lamp burned out. Replace.
ALT warning light fails to extinguish. Circuit breaker tripped. Defective alternator output circuit. Reset, if it trips a second time, check circuit breaker, replace if defective. Check and repair.
Test switch fails to activate warning lights. Bad switch or connections. Check wires and replace switch if necessary.
LO BUS warning light fails to illuminate. Lamp burned out. Replace lamp.
HTR OVERTEMP light fails to illuminate. Lamp burned out. Replace lamp.
HTR OVERTEMP light fails to extinguish. Temperature in heater vent jacket to high. Press reset button in nose, then activate FAN only for a minimum of two minutes.
39-10-00 Page 39-6 Issued: April 1, 1997
3B6
REPLACEMENT OF ANNUNCIATOR PANEL LIGHT BULBS.
Replacement of a bulb does not require removal of the annunciator panel. The lenses are designed to be a friction fit in the annunciator panel and the light bulbs fit into the back side of the lenses. To replace a defective bulb, simply pull the lens out of the annunciator panel. Withdraw the defective bulb from the lens and replace with a new bulb. Align the key on the lens with the key way on the annunciator panel socket and press the lens into position.
REMOVAL AND INSTALLATION OF VACUUM SENSOR SWITCH.
The vacuum sensor switch for each engine is mounted on the pressure regulator attached to the aft side of the firewall.
1.
Remove nacelle panels as necessary to gain access to the sensor switch.
2.
Note the position of the wires on the sensor switch, then disconnect the wires from the switch.
3.
Unscrew the sensor switch from the pressure regulator.
4.
If a new switch is not to be installed immediately, cover the opening to prevent dirt or other foreign matter from entering.
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