SYSTEM DESCRIPTION, INSTALLATION, AND MAINTENANCE MANUAL
MCS--4200/7200 Multi--Channel SATCOM System
23--20--35
15 Jul 2006
Honeywell International Inc. Do not copy without express permission of Honeywell.
Page 6--8
(3) The HPA and HSU store their functional test and CM failure records in nonvolatile
memory designated as the LRU failure memory log. Each LRU failure memory log is
capable of being interrogated and cleared. The SDU contains a nonvolatile memory
that serves as a system failure memory log. Functional test results supplied by the
HSU, HPA(s), ACU/BSU(s), LGA diplexer/LNA, and the SDU itself are recorded in
this system failure memory log. The system failure memory log is capable of being
interrogated and cleared for each LRU individually. Each LRU failure memory log and
the system failure memory log is capable of recording at least 1000 failures.
(4) The HPA, HSU and other system LRUs supply failure information to the SDU for
storage in the system failure memory log. In the absence of any detected failures
during a flight leg, the SDU records the flight leg counter, flight number, ICAO
address, date, and Greenwich Mean Time (GMT) at the flight leg transition. The SDU
also records the aircraft identification for display on the SCDU and CFDS
maintenance pages.
(5) Class -- The SDU declares and stores the classification (Airbus/Douglas CFDS) of
failure (one, two, three) for each entry in this field.
•
Class 1 failures are indicated in flight to the crew by the CFDS because they have
operational consequences for the current or next flight(s).
•
Class 2 failures are not automatically indicated in flight to the crew by the CFDS
because they have no operational consequences for the current or next flight(s),
but are indicated to the crew on the ground because they cannot be left
uncorrected until the next routine scheduled maintenance check.
•
Class 3 failures are not indicated to the flight crew because they can be left
uncorrected until a routine scheduled maintenance check. An accumulation of
Class 3 failures can lead to a Class 2 or Class 1 failure.
•
Aircraft Identification -- The aircraft identification (i.e., the tail number) is made up
of nine alphanumeric characters. The SDU obtains the aircraft identification from
the CMC or CFDS through ARINC labels 301, 302, and 303 (if available).
G. Failure Reporting
(1) General
(a) Active failures include those internal and external failures deemed to be currently
failing while the aircraft is on the ground or airborne. Unlike failure recording that
excludes recording external failures while on the ground, failure reporting has its
own set of criteria as specified in the following paragraphs.
(2) HPA Failure Reporting
(a) General
1
The HPA reports its functional test/CM failure status by lighting its front panel
LEDs, and through communication to the SDU.
(b) HPA Front Panel Indicators and Controls
1
The HPA indicators and controls are given in Table 6-2.
