Equipment Cooling

Question 1

What is the equipment cooling system for:

Answer 1

Provides cooling for flight deck panels and electrical components

Question 2

System on the ground:

Answer 2

-Before Engine Start: (above 7C)

Inboard supply and exhaust valve opens, skin heat exchanger is closed

-After Engine Start

Skin heat exchanger valve opens, inboard + exhaust valve closes
Air is recirculated through the skin heat exchanger using supply and exhaust fans for cabin pressurization

Question 3

System In-Flight:

Answer 3

Supply and exhaust valves closed, skin heat exchanger valve open
Only exhaust fan operates

IF exhaust fan fails, supply fan goes on

Question 4

Selector in “STBY”

Answer 4

1. Response to OVHT
2. ALL valves closed except bypass valve
3. Supply fan ON

Question 5

Selector in “OVRD”

Answer 5

1. In response to STBY not working or SMOKE
2. All valves closed EXCEPT Smoke override
3. Both fans off, air is diverted into the system and differential pressure causes reverse airflow

IF no reverse airflow after 1 minute “NO COOLING” light illuminates

Question 6

“VALVE” light illuminates

Answer 6

1. Any supply or exhaust valve not in commanded position

Note: If light remains on for more than 30 seconds pressurization may not operate