-
the main engine start,

 -
the air-conditioning. The APU bleed air system, installed in the APU compartment, is made of stainless steel and is fireproof. A hazard will not result if one of the ducts is ruptured. Overheat sensor elements are installed on the bleed air duct, between the APU check valve and the APU bleed control-valve. When the overheat sensor elements detect an overheat condition, the APU bleed control valve will close.

 B.
 Accessory Cooling The accessory cooling system supplies cooling air to the APU oil cooler and to the APU compartment. The system operates independently of the APU load compressor and the bleed and surge-air system (Ref. 49-52-00).

 2. System Description
__________________
 A. Bleed and Surge Air The APU load compressor supplies the APU bleed air. The quantity changes with the different bleed air demands of the pneumatic systems. Variable Inlet Guide Vanes (IGVs) (which are installed at the load compressor inlet) control the quantity of the bleed air. An APU bleed control valve is installed at the scroll outlet on the right lower part of the APU. The APU bleed control valve controls the air from the load compressor to the exhaust or to the pneumatic system of the aircraft. The Electronic Control Box (ECB) 59KD controls and monitors the APU bleed air supply and the surge air flow. You start and stop the bleed air supply with the APU BLEED pushbutton switch, which is on the AIR overhead panel 30VU in the cockpit.

 B. Accessory Cooling The accessory cooling system operates independently of the APU load compressor and the bleed and surge-air system. A cooling fan supplies sufficient cooling air to the oil cooler to keep the lubricating oil in the correct temperature range. It also supplies cooling air to the APU compartment to remove the heat which comes from the APU surface. The cooling fan is of the one-stage axial-flow type and the accessory drive gearbox turns the cooling fan rotor. The compartment cooling air flows through an outlet and into the APU compartment.

 BLEED AND SURGE AIR - DESCRIPTION AND OPERATION
_______________________________________________

R **ON A/C 001-003, 051-099, 401-499,
 1.
 General

_______ The APU load compressor supplies the APU bleed air. The quantity changes with the different bleed air demands of the pneumatic systems. Variable Inlet Guide Vanes (IGVs) (which are installed at the load compressor inlet) control the quantity of the bleed air. An APU load control valve and a surge control valve are installed on the outlet orifices of the bleed air T-duct. The APU load control valve stops or permits the bleed air flow from the APU to the pneumatic system of the aircraft. The surge control valve prevents a load compressor surge. The excess air passes through the valve to the exhaust cone. The Electronic Control Box (ECB) 59KD controls and monitors the APU bleed air supply and the surge air flow. You start and stop the bleed air supply with the APU BLEED pushbutton switch, which is on the AIR overhead panel 30VU in the cockpit.

 2.
 Component Location

__________________
 (Ref. Fig. 001)

 -------------------------------------------------------------------------------FIN | FUNCTIONAL DESIGNATION | PANEL|ZONE|ACCESS | ATA | | | | DOOR | REF.
 -------------------------------------------------------------------------------SENSOR ASSY - PNEUMATIC 316 316AR 49-51-13 SENSOR - TOTAL PRESSURE 316 316AR 49-51-14 SENSOR - STATIC PRESSURE 316 316AR 49-51-15 TRANSDUCER - DIFFERENTIAL PRESSURE 316 316AR 49-51-16 TRANSDUCER - TOTAL PRESSURE 316 316AR 49-51-17 TRANSDUCER - COMPRESSOR INLET PRESSUE 316 316AR 49-51-16 DUCT - BLEED AIR 316 316AR 49-51-42 VALVE - LOAD CONTROL 316 316AR 49-51-51 VALVE - SURGE CONTROL 316 316AR 49-51-52
 3. System Description
__________________
 (Ref. Fig. 002)

 A. Primary Components The bleed and surge air system has the subsequent primary components:
 -
a total pressure sensor,

 -
a static pressure sensor,

 -
a bleed air duct,

 -
a total pressure transducer,

 -
a differential pressure transducer,

 Bleed and Surge Air - Component Location Figure 001 (SHEET 1)

R EFF : 001-003, 051-099, 401-499, 49-51-00Page 2 Config-1 Aug 01/05
 CES

 Bleed and Surge Air - Component Location Figure 001 (SHEET 2)

R EFF : 001-003, 051-099, 401-499, 49-51-00Page 3 Config-1 Aug 01/05
 CES

 Bleed and Surge Air - Block Diagram
 Figure 002

 CES  -a compressor inlet pressure transducer,

 -an APU bleed valve,
 -a surge control valve.
 B. Bleed Air The bleed and surge air system supplies the APU bleed air from the load compressor to the aircraft users.
　
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