XA ALL EXCEPT LH 011-099;  AZ 221-299; SN 351-399;  16 Page 401 IB 406-499; AT 701-799  Sep 25/94

34-31-11

GLIDE SLOPE ANTENNA SEE A HYBRIDS, B554 AND B555  VOR/ILS RECEIVER NO. 3  VOR/ILS RECEIVER NO. 1 
P31 PANEL 
P32 PANEL BSEE  VOR/ILS RECEIVER NO. 2 

GLIDE SLOPE ANTENNA 
SWITCHING PANEL  LEFT AND CENTER 
G/S ANTENNA HYBRID, 
A  B554 

RIGHT G/S ANTENNA HYBRID, B555

NOTE: 4-PORT HYBRIDS ARE OPTIONAL,____
 EITHER TYPE MUST BE REPLACED 
IN PAIRS.  DO NOT INSTALL A REMOVAL AND INSTALLATION 
3-PORT HYBRID IN ONE SYSTEM
 AND A 4-PORT IN THE OTHER B 

OR VISA VERSA.
Glide Slope Antenna Hybrid Installation
Figure 401 (Sheet 1)

EFFECTIVITY

LH 001-010; AF 101-114;SN 301-350; IB 405;
799 Page 402 AZ 201-220
34-31-11

Dec 25/91
HYBRIDS, B554 AND B555 GLIDE SLOPE ANTENNA  VOR/ILS RECEIVER  VOR/ILS RECEIVER 
AND COAXIAL RELAYS,  NO. 3  NO. 1 
B404 AND B405 
SEE  C 

P31 PANEL
SEE D  VOR/ILS RECEIVER NO. 2
P32 PANEL
GLIDE SLOPE ANTENNA LEFT AND CENTER
SWITCHING PANEL
G/S ANTENNA HYBRID, B554
C
RIGHT G/S ANTENNA HYBRID, B555

NOTE: 4-PORT HYBRIDS ARE OPTIONAL, EITHER TYPE MUST BE REPLACED IN PAIRS. DO NOT INSTALL AREMOVAL AND INSTALLATION 3-PORT HYBRID IN ONE SYSTEM AND A 4-PORT IN THE OTHERD OR VISA VERSA.
Glide Slope Antenna Hybrid Installation Figure 401 (Sheet 2)

EFFECTIVITY AF 115-151, AND AF 157,161,183, 184 WITHOUT SB 34-2264799 Page 403
34-31-11

Sep 25/94
COAXIAL RELAYS, HYBRID, B554 AND ESEE GLIDE SLOPE ANTENNA B404 AND B405 
P31 PANEL 
SEE  F 
P32 PANEL 
GLIDE SLOPE ANTENNA SWITCHING PANEL E 

REMOVAL AND INSTALLATION F
Glide Slope Antenna Hybrid Installation
Figure 401 (Sheet 3)

VOR/ILS
VOR/ILS
RECEIVER

RECEIVER
NO. 3
NO. 1
VOR/ILS RECEIVER NO. 2
LEFT G/S ANTENNA HYBRID, B554

EFFECTIVITY AF 121,122,152-156,158-160,162-
182,185-199, AND AF 157,161,183,
184 WITH SB 34-2264; GN ALL; 799 Page 404

34-31-11

MD ALL; VM ALL Sep 25/94
 GLIDE SLOPE ANTENNA SYSTEM - TROUBLE SHOOTING
_____________________________________________
 1.  General
_______

 A.  The following trouble shooting procedures are based on performance of the operational and system tests and are presented in tree-type format. The test steps (heavy-line box) 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.  Before performing this test, perform the VOR/ILS system trouble shooting 34-31-00. Substitution of suspected faulty components such as the receiver or HSI with known serviceable unit(s) must be made. The scope of this test extends beyond the operational test and necessitates the use of test equipment outside the airplane. Reflections of the test signal by the ground, engine nacelles, buildings, ground support equipment, etc, cause an unstable test environment for the glide slope antenna and system as shown in Fig. 101. Therefore, any obstruction which might distort the test readings must be removed prior to comparing the test results for one system against the other. Do not use absolute sensitivity values. Also, rf reception must be limited to the antenna(s) under test by the use of aluminum foil tape over the other glide slope antennas or the disconnecting of parallel rf runs at the station 400 hybrid coupler(s). The following procedure specifies disconnecting the rf runs at the hybrid couplers. In addition, check aft nose gear door antenna panels and cavity access panels for the presence of paint or corrosion and for missing screws which allow the panels to bow and detune the door cavity. Also guard against various metal coatings and treatments which compromise bonding, ie, faying surfaces must be alodined, not anodized and hardware must be Cd-coated instead of Moly-Coated. When replacing antenna access panels, ascertain that the faying surface is clean with an undamaged alodine coating, then tighten bolts for proper surface to surface contact.
　
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