Purpose of This Report

This document sets forth general philosophy, basic guidance and certain specific recommendations concerning the design and use of BITE. It is intended that this document will provide a better mutual understanding among the designers and users of BITE with a view toward achieving an optimum balance among the critical factors of BITE effectiveness, cost and complexity.

This document also includes a description of a Centralized Fault Display System (CFDS). The CFDS was conceived to provide access to individual LRU BITE capabilities from a centralized location (the cockpit). The purpose of the CFDS is to accumulate fault data, present (on demand) this data to a maintenance operator, and assist troubleshooting by performing diagnostic tests and performing verification testing after installation of a replacement unit. The CFDS is comprised of the BITE portions of avionic subsystems (only those included in the system), a centralized display unit, and an interface unit.

This document discusses the role of BITE in the airlines' maintenance concept and the BITE characteristics desirable in all avionic equipment. Beyond the guidance applicable to BITE in general, it is the intent of this document to provide specific guidelines for the equipment which make up the CFDS to provide for:

• Storage of in-flight fault data in appropriate LRUs for shop use.

• Reporting of fault status in the air and on the ground.

• Ground test capability for isolating faulty LRUs, performance verification and system level testing.

• Storage of total subsystem fault data in a transportable medium (optional).

With the exception of In-Flight reporting, the term "BITE", as used herein, encompasses all of the above maintenance functions, whether the unit is included as part of the CFDS or not.

Airframe and equipment designers are encouraged to take advantage of this guidance information starting with the earliest phases in the design of new equipment. Users may also find this information helpful in standardizing maintenance procedures and in securing appropriate recognition for such procedures from the regulatory agencies. It is particularly important that the guidance set forth herein should be considered in the overall perspective of the users' needs, rather than some more limited objective