B757 Review Questions

Air Systems

• What is the maximum altitude the APU can provide pneumatic pressure for

pressurization?

• 17,000’.

Air Systems

• An illuminated BLEED light indicates the air temperature is high and the Bleed Air

Valve has closed. Is this situation re-settable by the crew?

• Yes, after the duct has cooled

Air Systems

• TRUE/FALSE: The APU bleed air valve automatically closes after engine start when

APU bleed air is no longer required.

• TRUE

Air Systems

• With the engine not running and its bleed air switch selected to ON, the OFF light in

the bleed air switch will?

• Be illuminated

Air Systems

• Will an Engine Bleed Air valve open when it is selected on but the engine is not

running?

• No.

Air Systems

• TRUE/FALSE: If an overpressure of the associated engine bleed air system occurs due to a failure of a HP valve to correctly modulate bleed air pressure, the HP valve

can only be reset by maintenance.

• TRUE

Air Systems

• What happens anytime the left recirculation fan shuts down?

• The overboard exhaust valve latches open.

Air Systems

• With the pack switch in AUTO, a pack off light indicates what condition?

• Loss of air to the pack valve.

Air Systems

• Under what condition will the overboard exhaust valve be closed?

• When cabin pressure differential is greater than 2.5psi.

Air Systems

• When does the AUX fan supply cooling air to the E/E compartment?

• When the HDG is the only source of AC power, or if both supply fans are

inoperative.

Air Systems

• When are the recirculation fans inhibited?

• Cargo fire armed, or E/E smoke.

Air Systems

• What is the normal flow of exhaust air from E/E equipment and cockpit avionics?

• Normally is blown into the air conditioning mix manifold by the left circulation fan. If the pressure differential is less than 2.5psi, the

overboard valve is open and the E/E air is vented overboard.

Air Systems

• What determines the temperature of the conditioned air from the packs?

• The temperature requiring the coolest air.

Air Systems

• What happens to the pack temperature if you turn the trim air switch off?

• The air conditioning packs provide air for an average cabin temperature, 75 degrees.

Air Systems

• What signals the packs to go to high flow?

• For ground operation whenever the APU or ground source is supplying air for air conditioning, and/or if one pack or

recirculation fan is inoperative.

Air Systems

• What will inhibit high flow?

• An inoperative engine.

Air Systems

• What is the cabin rate of climb and descent during automatic operation with the cabin

rate controller set on the index mark?

• Cabin climbs at 500 fpm, and descend at 300fpm.

Air Systems

• What does the illumination of the BLEED light indicate?

• Bleed air over temperature.

Air Systems

• When the BLEED light is extinguished can the bleed be reset?

• Yes.

Air Systems

• What does the illumination of the HI STAGE light indicate?

• An overpressure problem and the engine high pressure bleed air valve is

automatically locked closed and can only be reset by maintenance on the ground.

Air Systems

• What cabin pressure will the system seek after more than one minute in cruise?

• The higher of scheduled cabin altitude, or landing altitude.

Air Systems

• If pressurization switch AUTO 1 is selected, when will AUTO 2 be checked for

normal operation?

• During a self test after each landing.

Air Systems

• What turns on the cabin altitude light?

• Cabin pressure above 10,000’.

Air Systems

• What action resets the cabin altitude light?

• Cabin pressure descending below 8,500’.

Air Systems

• What turns on the pressurization INOP amber light?

• Both auto 1 and 2 inoperative, or the selector switch in the manual position.

Air Systems

• What is the power source of the “Manual” position for the outflow valve?

• DC motor

Air Systems

• With the pack switch in AUTO, the PACK OFF light and INOP light would indicate

what condition?

• The pack has shut down due to excessive compressor outlet temperature.

Air Systems

• Can you reset a Pack trip?

• Yes, when the pack cools to a temperature below overheat level.

Air Systems

• What does the illumination of the Trim Air Off light indicate?

• The trim air switch is off, or a fault with the trim air controller.

Air Systems

• What will cause illumination of the compartment temperature INOP light?

• The compartment temperature control is off, trim air switch is off, overtemp of

associated distribution duct, or fault with trim air controller.

Air Systems

• When does the DUCT LEAK light illuminate?

• When there is a leak in the pneumatic supply ducting.

Air Systems

• Will a bleed over temperature close the engine bleed valve and if so can it be reset?

• Yes, it will close the engine bleed and it can be reset once the bleed is cooled.

Air Systems

• What could cause a pack INOP light to come on without a PACK OFF light?

• High pack outlet temperature or a fault in the automatic controller.

Air Systems

• What happens if you get a smoke light?

• Smoke in exhaust duct - Overboard exhaust duct is latched opened left recirculation fan is turned off in flight. Left air conditioning pack goes to high

flow.Smoke in supply duct - Overboard exhaust duct is

latched opened left recirculation fan is turned off in flight. Both air conditioning packs go to high

flow, right recirculation fan is turned off, overheat light is inhibited for 5 minutes.

Air Systems

• What are the engine bleed air valves controlled and activated by?

• Electrically controlled and pneumatically activated.

Air Systems

• When could you get an OVHT light?

• Insufficient airflow on the ground, selected supply fan not operating, left recirculation

fan not operating and overboard valve closed, both aft exhaust fans inoperative.

Air Systems

• Overboard exhaust valve is normally open when?

• When differential pressure is low, below 2.5psi

Air Systems

• If an automatic switchover to the alternate automatic controller occurs, how is the crew

alerted?

• STATUS prompt on the lower EICAS screen and a status message of CABIN ALT

AUTO 1 or 2

Air Systems

• The _____ bus provides electrical power for the DC motor when the selector is held in

the CLIMB or DESCEND position.

• Standby DC Bus

Air Systems

• TRUE/FALSE: When the throttles are advanced for takeoff, the outflow valve closes a small amount causing the cabin

altitude to descend slightly below the takeoff airport elevation.

• TRUE

Air Systems

• The landing field altitude can be set between ?

• -1,000 and 14,000 feet

Air Systems

• The MANUAL selector/control is spring loaded to center activates the actuator __motor to operate the outflow valve.

• DC

Air Systems

• For normal landings, the cabin altitude decreases to ___ below the selected landing altitude to ensure the cabin is pressurized on

landing.

• 100’

Air Systems

• The _____ altimeter provides the barometric correction to the landing altitude

setting

• Captains

Air Systems

• Concerning the pressurization system, each automatic pressurization controller operates the outflow valve actuator through' it's own

___ motor.

• AC

Air Systems

• Is an EICAS alert (advisory, caution, or warning) provided when failure of a single automatic pressurization controller occurs?

• No

Air Systems

• Condition: The Pack outlet temperature is excessive. The crew has selected Standby to acquire manual control of the pack output

temperature. The INOP light has extinguished. What is the system fault?

• Automatic Temperature Controller

Air Systems

• If the Pack outlet temperature becomes excessive, will the pack automatically shut

down?

• No

Air Systems

• Since the packs operate to maintain the temperature of the cabin zone requiring the lowest temperature, how are the other zones

maintained at their desired temperature?

• Trim air is added to the air delivered to the other zones

Air Systems

• What is indicated by an illuminated PACK OFF light in a Pack Reset switch

• There is a loss of supply air to the pack, the Pack Control Selector is OFF, or a Pack Trip has occurred

Air Systems

• If the Pack outlet temperature becomes excessive, the pack will operate in full cold.

How can the crew immediately acquire manual temperature control of this pack?

• Select Standby Mode

Air Systems

• When there is a failure of the automatic pack temperature controller, the

temperature control valve

• Remains in the existing position

Air Systems

• When is the Pack Outlet set to high flow?

• On the ground with the APU or Ground air as the only pneumatic source, in flight for

the respective Pack with its recirculation fan off or inoperative, or In flight when one

pack is off or inoperative

Air Systems

• If the Pack outlet temperature becomes excessive, what automatically happens?

• The Pack is set to full cold