DISTRIBUTION - DESCRIPTION AND OPERATION

** ON A/C NOT FOR ALL

1. General

Pneumatic System - Schematic ** ON A/C NOT FOR ALL

The pneumatic system is divided into sub-systems as follows:

A. The Temperature and Pressure Regulating System for the Bleed Air from the engine compressor (Ref. 36-11-00).

Pneumatic System - Schematic ** ON A/C NOT FOR ALL

Component Location - Engine and Pylon ** ON A/C NOT FOR ALL

Component Location - Wing ** ON A/C NOT FOR ALL

Component Location - Avionics Compartment ** ON A/C NOT FOR ALL

This system is installed in the nacelle and pylon of each engine and includes:

an Intermediate Pressure Bleed Check (IPC) Valve,
a High Pressure Bleed Valve (HPV),
a Pressure Regulator Bleed Valve (PRV) which permits or stops the bleed air supply. It also keeps the downstream pressure to a specified limit with a Bleed Pressure Regulated Valve Control Solenoid ,
an Over-Pressure Valve (OPV) which protects the downstream pneumatic system if the PRV does not operate,
a bleed air precooler exchanger (air-to-air) which controls the air temperature downstream of the system. The engine fan supplies cooling air through a Fan Air Valve (FAV) to the precooler. A Fan-Air Valve Control Thermostat installed downstream of the precooler controls the butterfly plate of the FAV,
an Exchanger Outlet Temperature Sensor which monitors the temperature in the ducts,
two presssure transducers which monitor the pressure in the ducts,
two Bleed-air Monitoring Computers (BMC1 and BMC2) which receive information from the sensors. They monitor the system and control its operation,
two temperature sensors which detect overtemperature in ducts and give temperature indication.

This system is installed in the nacelle and pylon of each engine and includes:

an Intermediate Pressure Bleed Check (IPC) Valve,
a High Pressure Bleed Valve (HPV) which is contolled by a solenoid (Chapter 71).
a Pressure Regulator Bleed Valve (PRV) which permits or stops the bleed air supply. It also keeps the downstream pressure to a specified limit with a Bleed Pressure Regulated Valve Control Solenoid ,
an Over-Pressure Valve (OPV) which protects the downstream pneumatic system if the PRV does not operate,
a bleed air precooler exchanger (air-to-air) which controls the air temperature downstream of the system. The engine fan supplies cooling air through a Fan Air Valve (FAV) to the precooler. A Fan-Air Valve Control Thermostat installed downstream of the precooler controls the butterfly plate of the FAV,
an Exchanger Outlet Temperature Sensor which monitors the temperature in the ducts,
two presssure transducers which monitor the pressure in the ducts,
two Bleed-air Monitoring Computers (BMC1 and BMC2) which receive information from the sensors. They monitor the system and control its operation,
two temperature sensors which detect overtemperature in ducts and give temperature indication.

This system is installed in the nacelle and pylon of each engine and includes:

an Intermediate Pressure Bleed Check (IPC) Valve,
a High Pressure Bleed Valve (HPV),
a Pressure Regulator Bleed Valve (PRV) which permits or stops the bleed air supply. It also keeps the downstream pressure to a specified limit with a Bleed Pressure Regulated Valve Control Solenoid ,
A solenoid valve which allows the air in the sense line between the PRV and the HPV to vent to the atmosphere. This causes the HPV to close.
an Over-Pressure Valve (OPV) which protects the downstream pneumatic system if the PRV does not operate,
a bleed air precooler exchanger (air-to-air) which controls the air temperature downstream of the system. The engine fan supplies cooling air through a Fan Air Valve (FAV) to the precooler. A Fan-Air Valve Control Thermostat installed downstream of the precooler controls the butterfly plate of the FAV,
an Exchanger Outlet Temperature Sensor which monitors the temperature in the ducts,
two presssure transducers which monitor the pressure in the ducts,
two Bleed-air Monitoring Computers (BMC1 and BMC2) which receive information from the sensors. They monitor the system and control its operation,
several temperature sensors (provided for regulation) which detect overtemperature in ducts and give temperature indication.

B. The Bleed Air and Crossbleed (Crossfeed) System of the Auxiliary Power Unit (APU) (Ref. 36-12-00)

Component Location - MID and AFT Fuselage ** ON A/C NOT FOR ALL

This system is installed in the MID and AFT fuselage and contains:

a crossbleed valve which isolates or connects the right and left bleed air and distribution systems,
an APU bleed load valve which is a part of the APU. This valve controls the bleed air flow from the compressor of the APU when the supply system of the engine is off or does not operate,
an APU bleed check valve in the APU duct which protects the APU against bleed air from the engine(s).

C. The Ground Supply of Compressed Air (Ref. 36-13-00)

Component Location - Lower Fuselage ** ON A/C NOT FOR ALL

This system is installed in the lower MID fuselage on the left side and includes a ground connector behind panel 191DB. A check valve is installed inside the ground connector. This stops the loss of air when the ground supply unit is not connected. The HP air is supplied to the distribution systems through the ground connector.

D. Environment Protection (Ref. 36-14-00)

Protection of the Pylon and the Nacelles
This system is installed between the engine pylons and the fuselage. It has a protection function of the wing leading edge and the nacelle. If there is a major leak in the pneumatic system, a door opens and the pressure is released.

[Rev.10 from 2021] 2026.04.01 12:37:05 UTC