T55072
EFFECTIVITY
CONFIG 2 AT ALL; AZ ALL; IB ALL; SN ALL;
799 Page 109
34-31-00
Apr 25/81
VOR/ILS NAVIGATION SYSTEM - TROUBLE SHOOTING
____________________________________________
1. General_______
A. The following trouble shooting procedures are based on performance of the system operational test using VOR/ILS navigation system 1. Trouble shooting system 2 can be accomplished using the same procedures with the substitution of first officer for captain and RMI wide bearing pointer for RMI narrow bearing pointer. Trouble shooting alternate VOR/ILS receiver No. 3 can be accomplished by selecting the third receiver in place of receiver No. 1 or 2 and following the applicable procedures. The procedures are presented in tree-type format. The test steps (heavy-line boxes) are connected by shaded arrows to show the OK condition path. When all steps in the OK condition path check out, the system is operable.
B. When a test step does not check out, follow the NOT OK line to the box containing the trouble symptom. Turn to the procedure indicated and continue to follow a single line by analyzing the results of each test step until the required corrective action is determined. Perform the specified corrective action; then repeat the step at which the failure was encountered.
C. All trouble shooting procedures are based on the assumption that wiring is OK and that electrical power is available. If the corrective action in the procedure does not correct the problem, check wiring using the wiring diagram.
D. The VOR/LOC antenna switches are fail safe units, which if faulty can cause weak VOR reception. If only one system reception is weak, swap antenna switches to see if the problem follows the switch. Also check the antenna switching logic. Check that the rf distribution system coaxial connectors are properly connected. Cross-threaded or loose connectors cause weak rf reception. Compare the VOR test signal levels required to pull the warning flags from view in the flight instruments. Also compare the localizer test signal levels required for flag retraction (Ref 34-31-00, System Test).
NOTE: Do not compare VOR vs LOC test signal levels.
____
CAUTION: DO NOT ACTIVATE A "GLIDE SLOPE ANT TEST" SWITCH ON PANEL P2
_______ IF A GLIDE SLOPE ANTENNA SWITCHING FAILURE HAS BEEN REPORTED (G/S-1 ANT or G/S-2 ANT ANNUNCIATOR ON PANEL P2 ILLUMINATED). REFER TO 34-31-12, GLIDE SLOPE ANTENNA SYSTEM - TROUBLE SHOOTING, FOR THE PROPER FAULT ISOLATION PROCEDURE TO PREVENT POSSIBLE DAMAGE TO AUTOPILOT ACCESSORY BOXES.
2. Prepare for Trouble Shooting____________________________
A. Verify that all circuit breakers on the STANDBY BUS, ESS FLT INST BUS and FLT INST BUS NO. 2 on panel P7 and the MISC bus on panel P12 are closed.
EFFECTIVITY
AF 121, 122, 155-171, CONFIG 3 174-190, 195-199; VM ALL 01 Page 101 Dec 25/83
34-31-00
B. Place AP/FD mode select panel switches and controls as follows: Course Transfer - DUAL NAV Mode Select - HDG All Others - OFF COURSE Counters - 000
C. Position power control knobs (VHF NAV control panels) to VOR/ILS.
D. Position captain's VOR/ILS transfer switch (P1 panel) to CAPT 1 F/O 2.
E. Position both VOR/ILS-INS switches (P10 panel) to VOR/ILS.
F. Place flight controller TURN knob in detent position.
G. Place STANDBY POWER switch (P4 panel) to NORMAL or OFF position.
H. Check that STANDBY IGNITION switch (P5 panel) is in NORM position.
I. Provide electrical power Ref 24-22-00, Maintenance Practices (Apply Power).
EFFECTIVITY
AF 121, 122, 155-171, CONFIG 3 174-190, 195-199; VM ALL 01 Page 102 Dec 25/83
34-31-00
Close VOR 1 DC and VOR 2 DC circuit breakers on P7 and select a frequency of
108.00 MHz on captain's VHF NAV control panel. Hold TEST button on captain's VHF NAV control panel depressed while verifying that NAV flag in captain's HSI remains in sight for up to 5 seconds, retracts from view, and after 20 seconds reappears and remains in view. IF -
Close VOR 1 DC and VOR 2 DC circuit breakers on P7 and select a frequency of
108.00 MHz on captain's VHF NAV control panel. Actuate VOR self-test on captain's VHF NAV control panel while verifying that NAV flag in captain's HSI remains in sight for up to 9 seconds, retracts from view, then after 20 |5 seconds, reappears and remains in view. IF -
NOTE:____ Bendix RNA-34A receivers have up to a 3-second delay time for NAV flag
retraction.
OK
AF 155,156,158-160,162-171,174-182,185-190,195-199 AF 121,122,157,161,183,184
T33876
EFFECTIVITY
CONFIG 3 AF 121,122,155-171,174-190,
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