Piper Comanche PA-24 Service Manual page 831

12-3. Testing Locator Transmitter.
CAUTION: THE TRANSMITTER OPERATES ON THE EMERGENCY FREQUENCIES OF 121.5
AND 243 MHZ, BOTH THESE FREQUENCIES ARE MONITORED BY THE VARIOUS
FAA INSTALLATIONS. PERMISSION MUST BE OBTAINED FROM THE FAA/FCC
REPRESENTATIVE (OR OTHER APPLICABLE AUTHORITY) PRIOR TO TESTING.
KEEP YOUR TEST TRANSMISSION TO A MINIMAL DURATION.
Before performing any operational test of the transmitter, the following precautions should be observed:
A. Remove the access panel or cover to gain access to the transmitter.
B. Tune the aircraft communications receiver to 121.5 MHz and switch the receiver ON, deactivate
squelch, and turn the receiver volume up until a slight background noise is heard.
NOTE: If the aircraft is not fitted with a communications receiver, request the tower to listen for
your test.
C. Remove the ON/ARM/OFF switch guard from the switch and set the ON/ARM/OFF switch to ON.
Keep the switch ON for a few seconds only; then set the switch to OFF.
NOTE: The test transmission should have been picked up by the aircraft communications receiver
and/or control tower. During cold weather there may be a slight delay before transmission
occurs.
D. A transmitter which is functioning properly should emit a characteristic downward swept tone.
E. When the test is completed, reposition the ON/ARM/OFF switch from the OFF position to the
ARM position and reinstall the switch guard, and any access panel or cover removed.
NOTE: Whenever the unit is checked by moving the selector switch from the "ARM" to "ON"
position it must then be moved to the "OFF" position before reverting to the "ARM"
position again.
12-4. Inadvertent Activation.
In the event the Automatic Locator Transmitter is inadvertently activated, the transmitter switch must be
reset by gaining access to the transmitter. (Refer to Paragraph 12-2.) Remove the plastic cap from the
switch and place switch in the OFF position. To reset the transmitter for automatic operation return the
switch to the ARM position. Refit the plastic cap over the switch. Reinstall the access plate. The
transmitter is now ready for normal flight operation.
NOTE: As a routine precaution, it is recommended that the transmitter be replaced at the earliest
opportunity after inadvertent activation. Note, however, that the problem may not be in the
transmitter. Check the following:
1. Proper antennae spacing so as to minimize antenna conducted RF.
2. Rigidity of the transmitter installation.
NOTE: Inspect the external whip antenna for any damage. Avoid bending the whip. Any sharply bent or
kinked whip should be replaced. Antenna damage may cause structural failure of whip in flight.
XII - ELECTRONICS
PIPER COMANCHE SERVICE MANUAL
3H4
04/01/09