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MAINTENANCE MANUAL

 (b) To recall faults from memory, operate the built-in-test controls on the front panel of the FQPU as follows: 1) Pushing the PRESS TEST switch displays 88 on the fault and status code display indicating that the selected channel is powered and the displays are working. 2) Pushing the RESET switch clears all faults from memory. 3) Pushing the VERIFY switch carries out a test of the fuel quantity indicating system to determine if any faults currently exist in the system. The VERIFY switch will only inidicate whether or not a fault exists, it will not indicate what the fault is. To determine what the existing faults are, the BIT switch must be pressed. 4) Pushing the BIT switch shows the fault code, if a fault has been stored. Additional faults are shown by pushing the BIT switch for each fault stored.
 5)  The DISPLAY CHAN SEL switch allows selection of either FQPU channel.
 EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. GUN 001-010 ú

 28-41-00
 ú CONFIG ú 08 Page 36 ú Sep 20/95

A

757 MAINTENANCE MANUAL
 FUEL QUANTITY INDICATING SYSTEM (FQIS)- DESCRIPTION AND OPERATION
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 1.  General (Fig. 1)_______
 A.  The fuel quantity indicating system (FQIS) supplies fuel quantity measurement, calculation, and indication. The system contains tank units, compensators, densitometers, indicators, and a fuel quantity processor unit. The fuel quantity processor unit (FQPU, referred to as "the processor") does quantity computation and fault isolation for the FQIS system. The processor also controls pressure fueling for the airplane (AMM 28-21-00).
 B.  The fuel quantity indicating system is a microcomputer controlled system that uses the variable capacitance principle for fuel quantity measurement. The capacitance measured by the tank units is approximately proportional to the quantity of fuel in the fuel tank.
 C.  The FQIS contains the processor (FQPU), a fuel quantity indicator module (FQIM), 3 load select indicators (LSI), a load select control unit (LSCU), 3 compensators, 3 densitometers, 7 tank wiring harnesses, and 33 tank units.
 D.  The processor (FQPU) is the principle component of the FQIS. It is a microprocessor based computer, found in the main equipment center on the rack E3-4. The processor has an independent channel for each fuel tank so that a component failure or contamination in one fuel tank does not affect the quantity measurement for the other fuel tanks.
　
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本文鏈接地址：757 AMM 飛機維護手冊 燃油 CHAPTER 28 - FUEL 4(107)