OPERATING MANUAL
7-2
21833-3.4
NORMARC 7013
INSTRUMENT LANDING SYSTEM
Corrective maintenance ©1999 Navia Aviation AS
monitor data sets are stored at ¼ of this frequency.
• For the last 10 seconds, one data set is stored each second.
• For the last 30 seconds, monitor 1, 2, standby and maintenance data are stored every 5
th
second.
When a changeover or shutdown alarm occurs the RMS does the following:
1. Stores the ring buffer with the last 30 seconds of monitor and maintenance data from
before the alarm in an internal alarm storage buffer. This buffer resides in non-volatile
RAM.
2. Places an changeover or shutdown alarm event in the event list. This event includes alarm
state information for each monitor-channel. This information is used by the RMM software
for diagnosing the alarm event.
The RMS keeps the seven most recent alarm storage buffers. A changeover-only situation fills
one alarm storage buffer, while a changeover with subsequent shutdown situation uses two
alarm storage buffers.
No alarm storage buffers will be saved if the equipment is in service mode when the alarm
occurs. (Service mode is activated by any of the following switches: Local, Manual, Write Pro-
tect disable, Interlock Override and the Access Grant enable switch on the Remote Control.)
The data in the buffers can be downloaded by the RMM software when a user initiates an
alarm event diagnostics (if the data is not already downloaded), and used in the diagnostic
algorithms described in the following sections.
The operator initiates an alarm event diagnostics by first selecting a changeover or shutdown
alarm in the Event List and then selects the “Event diagnostics” button.
Once the alarm storage has been downloaded it is also possible to display the individual sam-
ples. This method can be used, in addition to the automatic diagnostic function, to find the
cause of changeover or shutdown alarms.
For information on how to download and display historical data see Chapter 5 in the Operating
Manual.
For detailed information about the algorithms used in the automatic Alarm event diagnostics,
refer to section 7.4.4.
7.2.4 Manual fault diagnosis
Should the automatic diagnostic functions fail or give misleading results, manual diagnosis
using external measurement equipment can be performed.
7.3 LRU change procedures
7.3.1 Replacing units
When replacing any faulty module(s), please follow this procedure:
• Make sure the ILS configuration file from the last flight check is available if one of the fol-
lowing boards need to be replaced: MO1212, LF1223, or RMA1215.
• Make a print report of the monitor and maintenance values to document what the key
parameters were before the faulty module(s) was/were changed.
• Power down the system.
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