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Harrier Failure Survival, Built-In Test Equipment (BITE) Unit

Technical Information

Catalogue No: C0543
Category: Maintenance Systems
Object Type: Control/Data Entry
Object Name: Harrier Failure Survival, Built-In Test Equipment (BITE) Unit
Part No: 250.D.40100
Serial No: 001/73
Manufacturer: Elliott Bros (London) Ltd
Division: Flight Controls [FCD]
Platform(s): Harrier
Year of Manufacture: 1973
Width (mm):
Height (mm):
Depth (mm):
Weight (g):
Location: Triple Shelf Unit M (control panels) [Main Store]

Failure Survival B.I.T.E.
Type No. 250.D.40100
Ref. No.
Ser. No. 001/73


Very little is known about this item. This later unit is six years into the Harrier programme and the panel has a simple update with square illuminated push buttons on the upper part of the panel. The construction suggests that it is located on the Harrier, probably in the equipment bay. It was used to check out the aircraft systems prior to flight by monitoring the Built in Test Equipment in the avionics and commanding test functions. The given depth excludes the ten 280mm long cables.

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.


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