©1999 Navia Aviation AS 21833-3.4 Periodic maintenance CAT I and II
OPERATING MANUALNORMARC 7013
INSTRUMENT LANDING SYSTEM
6-1
PART III MAINTENANCE
6 Periodic maintenance CAT I and II
6.1 Weekly inspections
Can be relaxed to 2-Weekly or Monthly intervals if allowed by the Authority.
Test equipment
• NM3710 Field Test Set with portable antenna.
• PC with RMM and printer
6.1.1 Field modulation measurements
On the established reference marks for Course Line (THR CL), Sector Width (THR 90)) and
(THR 150) carry out modulation measurements, record the values in Table 6-18.
6.1.2 Monitor Parameters recordings
(Can be changed to Monthly intervals if allowed by the Authority.)
• Tx1 to antenna. Open the RMM program in level 1.
• Open Monitor Window 1.
• Open Front Panel.
• Make a paper copy by “Print Screen” function. (Table 6-1)
• Tx2 to antenna. (Executed by tower personnel if ILS is not taken out of service.)
• Make a second paper copy by “Print Screen” function. (Table 6-2)
• Compare Monitor parameter values with previous records.
6.2 Monthly inspections
Test equipment
•Field Test Set
6.2.1 Field DDM measurements
Using the Field Test Set carry out DDM measurements versus azimuth angles according to
established marks in the near field area of the antenna array.
IMPORTANT:
No adjustments / alignments shall be done during a Periodic Maintenance. The
parameters should be recorded and compared with their nominal values only.
Over some time, the parameters may change due to natural variations. Variations of less
than 50% of their alarm limits, are considered normal. If a parameter is changing more
than 50% of it's alarm limit, it is likely due to a discrepancy / degeneration of a module,
cable etc. In this case, the reason for the discrepancy should be searched for.
If the result calls for changing a module, rephasing of cables etc., a flight check is often
required to verify that parameters are inside operating tolerances.
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