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BITE Monitor

Technical Information

Catalogue No: C0632
Category: Flight Control
Object Type: Module/Sub-Assembly/Component
Object Name: BITE Monitor
Part No: 7702-0021EX1
Serial No: 010
Manufacturer: Marconi-Elliott Avionic Systems Ltd
Division: Flight Controls [FCD]
Platform(s): Sea Harrier
Year of Manufacture: 1976
Dimensions: Width (mm): 108
Height (mm): 163
Depth (mm): 16
Weight (g): 131
Location: Rack RAA03 [Main Store]

Marconi Elliott Avionics
Type No 7702-0021EX1
Ser No 010


This module is part of the Built-In Test Equipment of the Harrier. The card may have been part of the Autostabiliser Computer but is more likely to have been in the pre-flight Failure Survival, Built-In Test Equipment (BITE) Unit. The module will carry out a specific LRU test when commanded.
The module is a development stage card shown by the EX1 in the Part No.

BITE (Built-In Test Equipment) is a troubleshooting system installed in modern jet aircraft. BITE monitors the engine and airframe systems and when a fault is found, isolates it and provides the maintenance personnel with a code that identifies the LRU, or line replaceable unit, that contains the fault.

The LRU will contain both initiated and automatic test sequences which are small programs designed to test specific functions

A computer will have tests run at start-up which are only run at that time as they would interfere with normal operation. Once the computer has stabilised cyclic tests (also called operation test) will be carried out.They are carried out permanently, because they do not disturb normal operation. Examples: Watchdog test (i.e. CPU reset). RAM test.
System tests are available to the maintenance staff, for troubleshooting purposes. These tests are similar to ground power-up tests, but more complete. Examples: Tests performed after the replacement of an LRU.
Specific tests are available only to specific systems.
They are performed to generate stimuli to other devices, such as actuators or valves.
They have major effect on aircraft (such as automatic moving of flaps etc.) They are performed only on ground by maintenance staff.


In 1988 the UK Ministry of Defence awarded British Aerospace a £170 million contract to      upgrade the Royal Navy's Sea Harriers with new radars, avionics, and weapons. The contract   covered modification of all RN aircraft to FRS.2 standard, and work started in October 1990.  The RN had 42 Sea Harrier FRS.ls out of a total of 57 delivered and an additional contract, to build 16 new FRS.2s was negotiated. The Automatic Flight Control System supplied by GEC Avionics includes:

·         Autostabiliser which provides three axis stability augmentation during take-off, transition and hover

·           Autopilot to provide height, heading and attitude hold.

An Autotrim function was incorporated during the aircraft mid-life update to further enhance the AFCS.


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