©1999 Navia Aviation AS 21833-3.4 Maintenance Procedures
OPERATING MANUALNORMARC 7013
INSTRUMENT LANDING SYSTEM
C-19
(g) Return the sideband power to normal.
3. Path angle alarms (integral).
(a) Connect the PIR to measure DDM in the carrier feedline (Facility CSB test connector).
(b) Using the PMDT, open Test DDM window, click on TX1 dominance Off button to activate 90
Hz predominance (assuming transmitter 1 is active to the antennas). If necessary adjust Inc or
Dec until the monitor course position channel has just passed the threshold of alarm. Measure
and record the carrier feedline DDM value on Navia Aviation Form “CEGS Monitor Reference
Data”. Confirm that the carrier feedline DDM is not more than established reference value. If
not within tolerance, corrective action is required.
(c) Measure and record the course monitor DDM on Navia Aviation Form “CEGS Monitor
Reference Data”. The course monitor DDM can be observed in the currently active Test DDM
window as parameter MON1 CL DDM Nom. Note that no tolerance is established for this
entry. It is used only to detect trends.
(d) Repeat the procedure in steps (b) and (c) with the TX1 dominance button activated to 150
Hz.
(e) Restore the TX1 dominance button to off.
4. SBO dephasing alarms.
(a) Insert a N type elbow in the CSB carrier feedline. (CSB phase retarded)
(b) Confirm that the phase change is within the operating tolerance in chapter 3.
(c) Repeat the procedure in step (b) with the SBO phase retarded.
(d) Remove the added line lengths.
5. Middle antenna dephasing alarms.
(a) Insert and adjust the test kit phaser in the middle antenna feedline until the clearance
monitor alarms. The test kit phaser should be the same as used for the reference flight check
that established the Navia Aviation Form "CEGS Monitor Reference Data" values. Also, the
test phaser should have been previously checked with a vector voltmeter to ensure accuracy.
A preferred alternate method is to add the same predetermined line length (type N or BNC
elbows, or equivalent) to both the lower and upper antenna outputs of the APCU.
(b) Record the change in degrees in the middle antenna dephasing column on Navia Aviation
Form “CEGS Monitor Reference Data”. Confirm that the value is within established reference
value. If not within tolerance, corrective action is required.
(c) Repeat the procedure in the above steps with the middle antenna phase retarded (the
same line length added to the middle antenna output).
(d) Restore the middle antenna phase to normal, or remove the test phaser or lines.
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