©1999 Navia Aviation AS 21833-3.4 Corrective maintenance
OPERATING MANUALNORMARC 7013
INSTRUMENT LANDING SYSTEM
7-1
7 Corrective maintenance
7.1 Overview
This chapter contains procedures for locating and replacing faulty Line Replaceable Units
(LRU).
7.2 Diagnostic functions
7.2.1 General description
If the LLZ or GP fails, the RMM software should be used to locate the faulty LRU.
The RMM software can perform two types of diagnostic tests based on the measurements
made available by the embedded RMS software in the NORMARC 7000 cabinet:
1. “Current data diagnostics”. The diagnose is here based on live data received from an con-
nected ILS rack or based on historical data sets (snap shots) of measurements previously
stored to disk.
2. “Alarm event diagnostics”. This diagnostics function attempts to report the cause of a trans-
mitter changeover or a changeover/shutdown situation. The diagnose is based on a partic-
ular alarm event in the event list and the corresponding measurements in an alarm storage
that will be downloaded from the rack.
The diagnostic tests are based on passive reading of various measurement points inside the
NM70XX cabinet and the data from the executive monitors. No special signals need to be
injected for the algorithms to work (although the transmitters must be turned on).
The operator needs to be logged in at access level 1 to perform a Current data diagnostics
and an Alarm event diagnostics. Since only access level 1 is required, the diagnostics tests
can therefore be performed locally or from a remote location using a modem connection.
7.2.2 Current data diagnostics
The Current data diagnostics is invoked by selecting the ILS | Current data diagnostics menu
item in the RMM software.
There are two typical cases in which the current data diagnostics function may be used:
1. On an operative ILS system, on which a warning situation is indicated. In this case the cur-
rent data diagnostics can be used to quickly find the cause of the warning without taking
the system out of service.
2. In manual mode after a transmitter changeover or shutdown situation (monitor alarm). The
system can then be set to transmit on air, and the current data diagnostics used to locate
the module that is causing the monitor alarms.
For detailed information about the algorithms used in the automatic Current data diagnostics,
refer to section 7.4.3.
7.2.3 Alarm event diagnostics
The RMS subsystem in the NORMARC 7000 cabinet continuously reads data sets from mon-
itor 1, 2 and the standby monitor. The last 30 seconds of data are stored in an internal ring
buffer. This buffer is partitioned in groups with different sampling periods:
• For the last 2 seconds, 10 data sets are stored each second for monitor 1 and 2. Standby
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