*
LRU replacement test.
EFFECTIVITY BEJ ALL 21-40-00
Page 6
D633W101-BEJ Sep 05/2002
777 AIRCRAFT MAINTENANCE MANUAL
AIR CONDITIONING -HEATING -GROUND TESTS
EFFECTIVITY BEJ ALL 21-40-00
Page 7
D633W101-BEJ Jan 05/2002
777 AIRCRAFT MAINTENANCE MANUAL
THIS PAGE IS INTENTIONALLY LEFT BLANK
21-43-00
Page 1 D633W101-BEJ Jan 05/2002
AIR CONDITIONING -FORWARD CARGO COMPARTMENT HEATING -INTRODUCTION
Purpose
The forward cargo compartment heating system keeps the compartment temperature above freezing.
General Description
The forward cargo heating system interfaces with the forward equipment cooling system. These systems include the components and the necessary logic to give cargo heating.
The forward cargo heating system has these components:
* Ducts.
The duct moves air from the forward equipment cooling exhaust duct into the compartment.
The equipment cooling system uses these valves to control the movement of exhaust air:
*
Equipment vent valve
*
Forward cargo heat valve.
The equipment vent valve and the forward cargo heat valve control the movement of exhaust air into the forward cargo heat duct or into the vent duct. The cargo heat duct supplies air equally into the compartment. The overboard exhaust duct controls the movement of exhaust air to the area near the forward pressurization outflow valve.
On the ground, the forward cargo heat valve normally moves between the open and the closed position as ambient temperature changes. The valve closes when the temperature at the TAT probe is more than 55F (13C). It opens when the temperature is less than 50F (10C).
The forward cargo heat valve is open in the air.
The position of the heat valve changes so that its position is opposite the position of the vent valve. For example, when the vent valve is open the heat valve is closed.
See the equipment cooling section for more information about the control and operation of the equipment cooling vent and forward cargo heating (SECTION 21-27).
EFFECTIVITY BEJ ALL 21-43-00
Page 2
D633W101-BEJ Sep 05/2002
AIR CONDITIONING -FORWARD CARGO COMPARTMENT HEATING -INTRODUCTION
EFFECTIVITY BEJ ALL 21-43-00
Page 3
D633W101-BEJ May 05/2002
AIR CONDITIONING -FORWARD CARGO COMPARTMENT HEATING -HEAT DUCT
Purpose
The forward cargo heat duct supplies equipment exhaust air into the forward cargo compartment.
Location
The forward cargo heat duct is below the floor of the forward cargo compartment, on the left side.
Physical Description
The rigid type duct connects to the forward cargo compartment heat valve. The diameter of the duct decreases aft of the valve. Near the valve, the diameter is approximately nine inches (23 cm). At the end of the duct, the diameter is approximately four inches (10 cm). The duct has holes on the inboard and outboard sides. There are more holes on the inboard side than on the outboard side. The holes supply air into the forward cargo compartment.
EFFECTIVITY BEJ ALL 21-43-00
Page 4
D633W101-BEJ Jan 05/2002
AIR CONDITIONING -FORWARD CARGO COMPARTMENT HEATING -HEAT DUCT
EFFECTIVITY BEJ ALL 21-43-00
Page 5
D633W101-BEJ May 05/2002
777 AIRCRAFT MAINTENANCE MANUAL
THIS PAGE IS INTENTIONALLY LEFT BLANK
21-44-00
Page 1 D633W101-BEJ Jan 05/2002
BOEING PROPRIETARY -Copyright # -Unpublished Work -See title page for details.
AIR CONDITIONING -AFT AND BULK CARGO COMPARTMENT HEATING -INTRODUCTION
Purpose
Aft and bulk cargo compartment heating controls the amount of pneumatic system air supplied to heat these cargo compartments.
General Description
The aft and bulk cargo compartments receive warm air from the pneumatic system. The aft and bulk cargo compartments each have two heat valves. One functions as a shutoff valve. The other functions as a temperature control valve. These valves open or close to supply more or less warm air to keep compartment temperatures within limits.
The cargo temperature select panel on the flight deck gives manual control of the temperature for the aft and bulk cargo compartments. Operation of the valves is from environmental control system miscellaneous cards (ECSMCs) in the system card files.
EFFECTIVITY BEJ ALL 21-44-00
Page 2
D633W101-BEJ Sep 05/2002
