User's Guide

Table Of Contents

DRAFT

Page 4-1

17 Mar 2016

23-15-87

SYSTEM DESCRIPTION, INSTALLATION, AND MAINTENANCE MANUAL

ARINC 781-500 SDU and SCM

TESTING AND FAULT ISOLATION

This section provides test procedures to determine the operational readiness of SDU units.

All of the tests are to be performed when the SDU is installed on an aircraft and connected to a TCP.

There are no operational test procedures defined for the SCM. SCM health is determined by accessing the SDU

BITE information.

If the A781-500 equipment passes all tests in this section but does not function according to the installation

requirements, the fault may be with equipment or wiring outside the A781-500 system.

This section includes:

• Operational and Diagnostic Testing

• Troubleshooting and Fault Isolation

• Adjustment/Alignment Procedures

• Modification History.

NOTE: Depending on the version of software installed, the MPU menus described may differ from those shown

as examples in this manual.

1. Operational and Diagnostic Testing

This section includes the following sections:

• General

• Test and Fault Isolation Equipment Requirements

• SDU Maintenance Port Utility

• Operational and Diagnostic Test Procedures.

A. General

The A781-500 system requires testing for one of the following reasons:

• To verify the operational readiness of the system after installation on an aircraft

• To verify that a fault exists and produce system reports for troubleshooting purposes

• To verify the operational readiness of repaired LRUs after re-installation on an aircraft.

This section includes test and fault isolation procedures for the A781-500 system. All test and load

procedures require the A781-500 SDU MPU, which is accessed by connecting to the maintenance

port of the SDU.

B. Test and Fault Isolation Equipment Requirements

Table 4-1 lists the equipment required to access the SDU Maintenance Port Utility and perform

operational and diagnostic testing on the SDU.

DRAFT as of

4 Mar 2016