Carburetor Ice Detection System Test - Piper Dakota Maintenance Manual

CARBURETOR ICE DETECTION SYSTEM TEST

Do not attempt to test probe or instrument by applying a voltage
to each. Any voltage over 2-volts will burn out probe lamp,
sensor, and instrument red light switching transistor.
l. To test probe:
a. Disconnect probe from instrument at knife connections.
b. Connect a red + ohmmeter test probe to black wire of ice detection probe.
c. In a subdued light (not in sunlight) touch black ohmmeter test probe to red wire of ice detection
probe. The ohmmeter reading should by approximately 600 ohms with ordinary light on probe
sensor.
d. Cover ice detection probe sensor with hand to eliminate most light. Ohmmeter reading should be
very high; approximately 10,000 ohms or more.
e. Remove ohmmeter black test probe from red wire and touch it to white wire. The ohmmeter
reading should be approximately 5 ohms. This indicates that probe lamp is operating.
f. Test probe housing for short to ground. Housing is insulated.
g. If test contained in previous steps are satisfactory, probe will operate satisfactorily.
2. To test instrument:
a. Disconnect probe at knife connections.
b. Apply +12 volts dc to red wire with a fuseholder.
Apply -12 volts dc to black ground wire.
c. Red carburetor ice light should light, if it does not, instrument is inoperative and must be returned
to manufacturer (see NOTE).
d. If red light comes on, touch red wire connector to black wire connector. Red light must go out. If it
does not go out, instrument is inoperative and should be returned to manufacturer (see NOTE).
3. To test probe and instrument's function:
a. Turn power on.
b. Turn sensitivity control up from its, full counterclockwise position until red light just goes out.
This should be between 1/4 to 3/4 turn.
c. Place a piece of paper in air gap of probe (between sensor housing lens). Red light should light.
The only FAA approved repair shop for this instrument is ARP
Industries, Inc.; 36 Ray Drive E.; Huntington, New York 11743;
Tel. 516-427-1585.
PIPER AIRCRAFT
PA-28-236
MAINTENANCE MANUAL
—CAUTION—
—NOTE—
2I8
71 - 60 - 00
Page - 71-17
Reissued: August 1, 1986