Equipment Cooling ***

Question 1

Equipment cooling provides cooling air for what compartment/systems?

Answer 1

• Flight deck equipment

* Electrical and equipment racks (E & E)

Question 2

When is warm exhaust air ducted overboard through the ground exhaust valve?

Answer 2

• Engines not operating
• Equipment cooling selector in NORM
• Ambient temperature moderate or high

Question 3

When does the equipment cooling system configure for flight?

Answer 3

• One or more engines on each wing is operating.

Question 4

How can you manually configure the equipment cooling system for flight?

Answer 4

• Positioning the Equipment Cooling Selector to STBY.

Question 5

Which valve is closed when equipment cooling is in closed loop mode?

Answer 5

• Inboard exhaust valve

Question 6

What is the source of equipment cooling air for the flight deck electrical equipment?

Answer 6

• With two or three packs operating, the flight deck equipment cooling source valve directs conditioned air into the flight deck electrical equipment.

Question 7

Describe the operation of the equipment cooling system with the Equipment Cooling Selector in OVRD.

Answer 7

• Provides equipment cooling in flight if internal fans are inoperative.
• Internal fans are not powered.
• Smoke/override valve opens.
• All other valves closed, no air flow to forward cargo.
• Cabin differential pressure draws air from the panels area on the flight deck, through the equipment cooling ducts to the E&E, to create a reverse flow of air across the equipment, then through the supply duct, then overboard.

Question 8

Under what conditions would the equipment cooling system revert to closed loop mode?

Answer 8

• LLCCAFR Selector in FWD LOW, BOTH LOW, FWD HIGH, with a forward lobe temp selector set lower than 10C
• If a single internal fan fails.
• When the MAIN CARGO FIRE ARM switch is pushed.

Question 9

If EICAS message EQUIP COOLING is displayed after you’ve switched to STBY mode with engines running, what has occurred?

Answer 9

• Airflow is inadequate
• Overheat is detected
• Smoke is detected
• Ground exhaust valve is not in commanded position

Question 10

A CLOSED loop of equipment cooling will stop what fan?

Answer 10

Supply fan

Question 11

Does the bypass valve OPEN in a CLOSED loop configuration?

Answer 11

YES

• Exhaust and Supply fans turns off

Question 12

In flight configuration of the equipment cooling system depends on?

Answer 12

LLCCAFR position and temp selected by FWD Lower Lobe Temperature Selector.

• With temp selected lower than 10C or the LLCCARF in FWD LOW/FWD HIGH/BOTH LOW - closed loop mode is selected.

Question 13

EQUIP COOLING - NORM - GROUND - NO ENG

Answer 13

• Exhausts overboard if ambient temp above 7C.
  (OPEN ground exhaust valve and CLOSE inboard exhaust valve)
• Exhausts into FWD LLC if ambient temp below 7C.
  (CLOSE ground exhaust valve and OPEN inboard exhaust valve)

Question 14

EQUIP COOLING - NORM - GROUND - 2 ENG - LLCCAFR OFF

Answer 14

• Enters flight configuration
• Exhausts into FWD LLC if:
• LLCCAFR is in OFF, AFT LOW, or AFT HIGH

Question 15

EQUIP COOLING - NORM - GROUND - 2 ENG - LLCAFR BOTH LOW

Answer 15

• If FWD LLC Temp selected to less than 10C or LLCCARF is in FWD LOW/FWD HIGH/BOTH LOW:
• Inboard Exhaust Valve - CLOSED
• Closed Loop Mode entered

Question 16

EQUIP COOLING - STBY

Answer 16

• Ground Exhaust Valve CLOSED
• Auto control bypassed to config for flight
• Inboard Exhaust Valve OPEN
• Single Fault = Closed Loop Mode

Question 17

EQUIP COOLING - OVRD

Answer 17

• Ground Exhaust Valve - CLOSED
• Inboard Exhaust Valve - CLOSED
• Equip Supply Valve - CLOSED
• Smoke/Override Valve - OPEN
• Diff Pressure exhausts cooling air overboard

Question 18

Equipment cooling provides cooling air for what compartments and systems?

Answer 18

• Flight Deck Equip
• Electrical & Equipment Racks

Question 19

What is the source of equipment cooling air for the flight deck?

Answer 19

With 2 or 3 packs operating, the flight deck equipment cooling source valve directs conditioned air into flight deck electrical equipment.