Quantity Measurement System
The Fuel or Potable Water Quantity Measurement System is an integrated system that that includes the sensor, signal conditioner, level sensor (Fuel Systems) and the display. The Fuel Quantity can be displayed in the cockpit on either an indicator (electro- mechanical or LCD) or on an Engine Instrument Caution Advisory System (EICAS). Potable Water Quantity is typically displayed on an indicator. FEATURESDISPLAY:
CONFIGURATION:
Fuel: The system has two microprocessor based subsystems for
fuel gauging and level sensing in the aircraft fuel tanks. COOLING: No external cooling is required. POWER: Uses aircraft supplied 28 VDC power. ON-BOARD
EXPERIENCE: Fuel Quantity Measurement System Capability
The Fuel Quantity Measurement System is an integrated system that provides fuel measurement, high and low level sensing, refueling and defueling control, fuel valves monitor control, and self calibration. System communication is through dual ARINC 429 Bus Engine Instrument Caution Advisory System (EICAS) interfaced with other aircraft systems, such as the Rogerson Kratos Integrated Instrument Display System (IIDS). The basic architecture of equipment consists of the following components:
The tank units are located in each fuel tank and any auxiliary tanks. The tank units are designed to provide compensation over the entire length by profiling and shaping the inner tube with a non-linear function. This results in a signal that is proportional to fuel mass. High and Low Level Sensors The optical level sensor consists of an IR Emitter and Detector. A high voltage level is detected when fuel is present between the IR Emitter and Detector. The optical sensors are monitored continuously by BIT circuitry. The BIT circuitry tests the optical fuel level sensors for contamination, bad connections and sensor failure. If a sensor failure occurs then the failure will be stored in memory and the signal processor will send a failure message to the EICAS. Signal Processor and Refueling Panel (SPRP) The SPRP contains the left and right signal processors and the refueling panel in one box. The refueling panel is used to control and monitor the refueling operation. Refueling can be accomplished either automatically or manually. The SPRP is also used in the defueling operation. Signal Processors The SPRP has separate left and right signal processors for redundancy. The signal processor measures the tank unit capacitance and leakage and performs the necessary signal processing. The left and right signal processors transmit the individual fuel tank quantity through the separate ARINC 429 buses. Non-Volatile Memory The left and right signal processors have separate non-volatile memories. The non-volatile memory consists of a serial Electrically Erasable Programmable Read Only Memory (EEPROM). The non-volatile memory is used to store detected faults and calibration information. Electrical Requirements The FQMS operates on aircraft power source of 28 VDC. The FQMS has two independent and isolated power supplies for each signal processor unit. The 28 VDC input will be protected so the functions provided by the refueling panel are independent of failures in the gauging system. Each of the FQMS power supplies generates the necessary voltages needed to power the logic and signal processing circuits. Each power supply regulator circuit includes both over-voltage and under-voltage protection. Potable Water Quantity Measurement System Capability
The Potable Water Quantity measuring System is an integrated system that provides potable quantity measurement. The architecture of the equipment consists of the following components:
The sensor is located in each tank. The sensor is profiled to provide a linear output as a function of water quantity remaining in the tank. Invasive Sensor: The invasive sensor element is a type element that is mounted to the surface of the tank and the probe extends into the interior of the tank and the potable water. The sensor coating in contact with the water meets FDA requirements. Non-Invasive Sensor: The non-invasive sensor element is installed within the non-metallic potable water tank wall between the liner and the inner tank windings and as such does not come in contact with the potable water. Signal Conditioner The signal conditioner measures the sensor capacitance as a linear function of the water quantity in the tank and converts the capacitance to a signal output voltage. Indicator The remotely located indicator displays the quantity of water in the tank. |
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