Airbus A-320 SOLENOID THERMOSTAT (T.L.T).

Transcription

1 Airbus A-320 SOLENOID THERMOSTAT (T.L.T). By Soumyadeep Das Raj shekhar Chatterjee

2 Solenoid Thermostat of the Engine Air Bleed System Part Number: 341E E E (AMD A) Component Maintenance Manual:

3 Physical Characteristics: Part number 341E 341E 341E (AMD A) Characteristics Weight (kg) Thermal Characterist ics (⁰C) Ambient Normal: -40 to 180. Exceptional -55 to 210 Triggering Point Solenoid Electrical Data Power Supply: 17 to 30 V DC Power Consumption: 0.4A with 30V DC Pneumatic Characteris tics(max air supply) From main ducting From upstream PRV From PRV pneumatic line 59.46PSIG PSIG 43.51PSIG PRV: Pressure regulating valve PSIG: Pound per Square Inch

4 Functional Overview: The T.L.T. is attached to under the wing of the Aeroplane in the Pylon region. It performs the function of regulating the intake of air from the compressor section of the engine which goes to the Pre Cooler Exchange (PCE) section. The air from the PCE is delivered and used for all the other pneumatic functions of the aircraft. Referring to the block diagram attached when the fan of the engine starts, the air pressure in the low pressure (LP) section is enough to force the air flow through the check valve. Once the engine is running and the pressure in high pressure (HP) section of the compressor is high, the LP valve closes and the air to the PCE goes from the HP region. The T.L.T controls the valves High Pressure Valve (HPV), Pressure Regulating Valve (PRV) and thus controls the amount of air and the air temperature in the downstream of PCE.

5 General Description The solenoid thermostat is installed in the pressure control and limitation section of the engine air bleed system. Pneumatically coupled to the Bleed Pressure Regulating Valve, it causes the former to regulate the pressure delivered by the air bleed system. Sub assemblies of Solenoid Thermostat. Solenoid Thermostat Thermostat Solenoid Valve Non return Sub assembly Sub assembly Sub assembly

6 Basic Operation: Operation of the T.L.T. Solenoid thermostat continuously senses the temperature of the air delivered downstream Pre cooler Heat Exchanger of the bleed air system and monitors the differential pressure between the upstream side of the bleed pressure regulating valve and the downstream side of pre cooler. It limits the air delivery through the bleed air system by controlling the bleed pressure regulating valve, pneumatically. Principle of operation: The solenoid thermostat covers the following functions: The overheat function Non return function Electrical closing functions. Upstream pressure limitation.

7 Overheat function: Cause: When a predetermined level of temperature is reached by the delivered air, the tube of stick expands and causes the invar rod to move Action: The invar rod, acting as a clapper causes the Bleed Pressure Regulating valve (BPRV) coupling line to leak. Effect: It causes the Bleed Pressure Regulating valve to regulate a lower pressure. Non Return Function: Cause: The diaphragm, sensing the differential pressure between the air supply downstream pre cooler and upstream Bleed Pressure Regulating Valve, is moved by a spring when the differential drops below a certain level due to a reverse flow. Action: The spring loaded clapper is moved by the air pressure admitted in the solenoid chamber, causing the pressure to vent from BPRV Effect: BPRV closes.

8 Electrical Closing Function: Cause: Coil of solenoid sub assembly is energized by means of electrical connector. Action: The core moves up and because of spring load the sub assembly enables clapper to leave its seat and thus to vent the coupling line. Effect: BPRV closes. Upstream pressure limitation. Cause: The Bleed Pressure Regulating Valve upstream pressure becomes excessive. Action: Safety valve releases the diaphragm sub assembly by venting this pressure.