*
L ISLN valve to C ISLN valve and APUSOV

*
C ISLN valve to R ISLN valve and C2 ADP

*
R ISLN valve to R Pack and R PRSOV.

If there are no inhibits, the ASCPC closes a valve or valves to isolate a leak then waits to see if the leak conditions goes away.
Any one of these conditions can inhibit the logic the ASCPC uses to find a wing or boby duct leak.
*
Left engine start

*
Right engine start

*
ADP operation within 3 minites after takeoff.

There are no inhibits that relate to a strut leak.
A strut leak is a leak in the duct at any of these areas:
*
Engine strut

*
Wing, between the engine strut and the inboard slat.

A wing duct leak is a leak in the duct adjacent to the inboard slat or in the under fuselage area forward of the main wheel wells.
A body duct leak is a leak in the duct in the main wheel wells or aft fuselage area, aft of the ECS bays. There is a left and right body duct. The left body duct connects to the left wing duct between the left and center isolation valves and connects to the C1 ADP and the APU. The right body duct connects to the right wing duct between the right and center isolation valve and connects to the C2 ADP.
See the duct leak and overheat detection section for more information (SECTION 26-18).

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AIR SUPPLY DISTRIBUTION -FUNCTIONAL DESCRIPTION -SUMMARY -NON-NORMAL CONDITIONS

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777 AIRCRAFT MAINTENANCE MANUAL

THIS PAGE IS INTENTIONALLY LEFT BLANK

36-20-00

Page 1 D633W101-BEJ Jan 05/2002
BOEING PROPRIETARY -Copyright # -Unpublished Work -See title page for details.

INDICATING SYSTEM -INTRODUCTION

General

The indicating system supplies the left and right air supply cabin pressure controllers (ASCPC) with air flow, pressure, and temperature data. The ASCPCs use the data for control of the pneumatic system and flight deck indications.
The pneumatic indicating system has these components:
*
Manifold pressure sensor (PM)

*
Manifold flow sensor (FS)

*
Manifold dual temperature sensor (TM)

*
Intermediate pressure sensor (PI).

The indicating system uses information from these components in the air conditioning system:
*
Pack flow sensor (ASCPC pack inlet differential pressure sensor)

*
ASCPC compressor discharge temperature sensor

*
ASCPC pack discharge temperature sensor.

The ASCPCs also get pressure, temperature and air flow rate information from the cabin temperature controllers.
The RVDTs are not part of the indication system but they do give valve position data to the ASCPCs. These valves in the pneumatic system use RVDTs:
*
Isolation valves (left, center, right)

*
APU shutoff valve (APUSOV)

* Fan air modulating valve (FAMV).
The ASCPC uses the data from the sensors and RVDTs to control the air supply flow, pressure, and temperature. The ASCPCs also use sensors to calculate open/close position data for valves that do not have RVDTs. The ASCPCs send the data to the AIMS and OPAS for flight deck indications. The ASCPCs also send the data to the cabin temperature controllers (CTC). The CTCs use the data for control and flight deck indications.
See the pack flow control section for more information on pack flow control and indication (SECTION 21-51).
See the pack flow cooling and mix manifold temperature control section for more information (SECTION 21-52).
See the engine air supply section for more information on the FAMV (SECTION 36-11).
See the air supply distribution section for more information on the isolation valves and the APUSOV (SECTION 36-12).

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777 AIRCRAFT MAINTENANCE MANUAL

INDICATING SYSTEM -INTRODUCTION

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INDICATING SYSTEM -ENGINE COMPONENT LOCATIONS

Engine Component Locations

There is one intermediate pressure sensor (IP) on each engine fan case at the 3:00 position.
The manifold dual temperature sensor is in the distribution duct downstream of the precooler that is in the engine strut.
Training Information Point

You open the right fan cowl on each engine to get access to the IP sensor.
For the left temperature sensor, you remove access panel 433AL on the strut to gain access. For the right temperature sensor, you remove access panel 443AL on the strut to gain access.
　
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