Air Conditioning Flashcards
There are 3 packs, what are they and where do they normally receive bleed air from?
Pack 1: Left pneumatic manifold
Pack 2: Center manifold
Pack 3: Right manifold
How many packs can the APU supply bleed air to? Ground and in-flight?
3 on the ground, 1 in flight up to 15000ft*
APU can not be started in flight
How many air zones are on the 747F
7
Pack Control Selector: what does it do?
Off:
closes the associated pack valve
resets pack fault protection system
extinguishes the sys fault light
displays EICAS memo message pack 1,2 or 3 OFF
—-
NORM
normal ops automatically alternate between pack temperature and controllers A and B
—
A: selects PTC A
—
B: Selects PTC B
Pack values are Blank controlled and Blank operated?
Electrically and pressure
If a pack is in HI FLOW how much will that increase the fuel consumption?
.3 % per pack
If Both PTC A and B fail what happens to the air conditioning packs?
They operate in backup mode and pack overheat protection system continues to operate normally. A pack overheat results in a shutdown
what does it do?: Pack RST switch
Resets pack fault protection system
restarts pack after automatic shutdown if fault no longer exists
Pack system FAULT Light
pack overheat or other system fault has occurred
may illuminate briefly when automatically or manually switching from pack temperature controller A to B or B to A
what does it do?: FLT Deck fan switch
On - with all packs off, recirculated cabin air supplied to flight deck
with at least one pack on, fan increases flow of conditioned air supplied to the flight deck, fan disabled in flight
FLT deck temperature selector
AUTO: auto control of flight deck temp, range from 65-85F 18-29C, in back up mode, range from C to W is set for the flight deck temp, cabin panel control is inhibited and automatic control of main deck zone temp is inhibited.
what does it do?: zone RST switch
resets zone temp controller if fault no longer exists
reopens master trim air valve if duct overheat no longer exists
reopens forward or aft lower lobe cargo trim air shut off valve if duct overheat no longer exists.
Zone system Fault Light
Illuminated (amber)
-temperature zone duct overheat or zone temperature controller fault has occurred
-master trim air valve failed closed
-trim air switch off
-master trim air valve closed and pack air continues to flow.
Main Deck temp selectors
auto: provides automatic control of main deck conditioned air temp
range c to w sets temp from 40C to 85C, in back up mode auto control of main deck temp is inhibited
what does it do?: Forward lower lobe temp selector
auto:
provides automatic control of forward lower lobe cargo conditioned air temperature when lower lobe cargo conditioned air flow rate selector in FWD HIGH, BOTH LOW and FWD LOW, range from 40-85c
Man: same as auto except its manual, resets forward lower lobe cargo conditioned air supply duct shutoff valve if valve closed by duct overheat
what does it do?: After lower lobe temp selector
Auto:
provides automatic control of aft lower lobe cargo conditioned air temperature when lower lobe cargo conditioned air flow rate selector in AFT HIGH, BOTH LOW and AFT LOW, range from 40-85c
Man: same as auto except its manual, resets after lower lobe cargo conditioned air supply duct shutoff valve is valve closed by duct overheat.
what does it do?: Trim Air switch
On:
automatic and manual selection of pack controller A or controller B enabled
mater trim air valve open and flight deck, upper deck, and main deck zone trim air valves operate automatically.
Off:
-master trim air valved closed
-pack output temperature in backup mode regulated to provide average flight deck temp from 65 to 85 as selected by flight deck temp selector in auto
-cabin temp panel control of 400f crew rest and upper deck zone temp inhibited
-pack controller A selected and both automatic and manual selection of controller b inhibited
-if pack controller A failed, pack controller b selected automatically
what does it do?: Equipment cooling selector
STBY:
ground exhaust valve closed
automatic control bypassed to configure system for flight: inboard exhaust valve open
with a single internal fault, equipment in board exhaust valve closes and cooling system reconfigures to allow internal closed loop recirculation of cooling air.
Norm:
Ground operation based on ambient temperature, position of lower lobe conditioned air flow rate selector and temp selected by the forward lower lobe cargo temp selector; equipment cooling air exhausted overboard or exhausted into forward cargo compartment.
2 or more engines running, lower lobe cargo conditioned air flow rate selector in OFF, AFT LOW, or aft HIGH, cooling air exhausted into forward cargo compartment and ground exhaust valve closed.
2 or more engines running, lower lobe cargo conditioned air flow rate selector in fwd low, both low or fwd high and forward lower lobe cargo temperature selected less tha 50, inboard exhaust valved closed and equipment colling air recirculated in a closed loop mode.
with a single internal fault equipment inboard exhaust valve closes and cooling system reconfigures to allow internal closed loop recirculation
OVRD:
inboard exhaust valve closed
ground exhaust valve closed
equipment supply valve closed: cooling air supplied through flight panels
smo0ke/override valve open; differential pressure exhaust cooling air overboard
what does it do?: Pack High Flow switch
on:
all operating packs configured to high flow
EICAS memo message PACKs high flow display
off:
LLCCAFR in high or both low - no effect on pack flow rates, all packs remain in high floow
LLCCAFR in fwd low, packs one and two controlled automatically, pack three remains in high flow
LLCCAFR in aft low - packs one and three controlled automatically. pack two remains in high flow
LLCCAFR in off - pack air flow controlled automatically.
what does it do?: AFT cargo Heat switch
On;
overheat shutoff valve opens to provide bleed air heat ot aft and bulk cargo compartments
temperature control valve closes and opens to maintain temperature
overheat shutoff valve closes and opens for overheat protection
Off;
shuts off aft cargo heat bleed air to compartment
AFT cargo temp light
illuminated amber;
compartment temperature excessive
overheat shutoff valve closes
what does it do?: Crew rest reset switch
Push:
opens and resets crew rest air supply valves if valves were closed by crew rest smoke detection system and smoke is no longer detected.
What is the LLCCAFR
low lobe cargo conditioned air flow rate selector
what does it do?: LLWWAFR selector
Off:
-Forward and aft lower lobe cargo air conditioning off
-resets lower lobe cargo conditioned air supply duct shutoff valves if valves closed by duct overheat.
FWD LOW: 2/3rds of pack three conditioned air disturbed to forward lower lobe cargo compartment.
AFT LOW: 2/3rds of pack two conditioned air disturbed to after lower lobe carbo compartment
BOTH LOW: 2/3rd of pack three and pack two conditioned air distributed to respectively to forward and aft lower lobe cargo compartments
FWD HIGH: All pack three conditioned air distributed to forwaed lower lobe cargo compartment
AFT High - all pack two conditioned air distributed to aft lower lobe cargo compartment
what does it do?: Landing Altitude switch
Push:
alternately changes landing altitude control between automatic and manual
manual
landing altitude set by rotating landing altitude selector
landing altitude followed by MAN displayed on primary EICAS
the EICAS advisory message LANDING ALITUDE is displayed
Automatic:
landing altitude set auto from FMC
landing altitude followed by auto displayed on primary EICAS
Outflow valve manual switch
ON:
outflow valve is controlled manually
bypasses automatic outflow valve control and cabin altitude limiter
OFF:
outflow valve controlled automatically bypasses automatic out
Cabin Altitude AUTO selector
NORM:
Cabin altitude controller A or B selected automatically on alternate flights
selected controller is the primary controller; selects secondary controller if primary controller fails
A - selects cabin altitde controller A as primary controller, selects B if A fails
B - selects cabin altitude controller B as primary controller, selects A if B fails
isolation valve light
Amber: isolation valve position disagrees with switch position
isolation valve switches
ON; valve open
off: valve closed
APU Bleed Air switch
On - valve commanded open when EICAS memo message APU running displayed
Off- valve closed
Engine bleed AIR system (SYS) FAult lights
amber:
bleed air overheat
bleed air overpressure or
HP Bleed valve open when commanded closed or
PRV open when commanded closed
Engine Bleed Air Switches
ON:
Engine bleed air valve opens for engine start
engine bleed air valve, PRV and HP bleed valve open by system logic when bleed air pressure available.
OFF
engine bleed air valve, PRV and HP bleed valve closed
PRV opens when nacelle anti-ice on, unless PRV closed by:
prior or present bleed air overheat, or
start valve not closed or
hp bleed valve failed open
engine bleed air off lights
amber: engine bled air valve closed
APU Bleed air valve light
APU Bleed air isolation valve position disagrees with switch position
When are Duct pressure, cabin altitude, rate, landing altitude, and differential pressure are displayed ?
Landing altitude man
cabin altitude in caution or warning range
cabin differential pressure in caution or warning range
ECS or ENG synoptic selected on secondary EICAS display
Bleed air duct pressure amb/white values
white = 12 psi and above
amber 11 psi or less
When is a TT (target temperature) displayed for a zone temp main deck and above?
at least one pack operating and
passenger temp selector in auto and
temperature control is not in backup mode
When is a TT (target temperature) displayed for a zone temp lower lobe?
FWD: displaced when LLCCAFR selector is FWD low, FWD high, both
AFT: Displayed when LLCCAFR selector is aft low, aft high or both
when is external air shown on the synoptic?
displayed if a pack is operating with APU and engines off, or bleed air ducts are pressurized with APU and engines off
What controls the packs?
two identical pack temp controllers (PTC) A and B.
how many channels does a PTC have to a pack?
3 channels 1 for each pack
What happens when a cargo fire arm switch is pushed?
Pack operation and air distribution is configured to starve the affected zone of fresh air, minimize air movement, purge smoke from the flight deck and passenger cabin, assure supply of fresh air to the flight deck
what happens when a pack overheats or PTC fault is detected?
the respective pack valve closes resulting in a pack shut down
pack flow rate is configured by?
the position of the LLCCAFR selector,
phase of flight and
number of operating air conditioning pack
–
in the event of pack shut down or failure the system reconfigures
Where does the forward lower lobe cargo conditioned air supplied from?
pack three
how is the volume of conditioned air supplied to the forward lower lobe carrgo?
LLCCAFR
with the LLCCAFR selector in FWD HI
all pack three air is distributed to the forward lower lobe cargo
all packs remain in high flow during cruise
with LLCCAFR selection in FWD LOW
2/3rds of pack three air is distributed to the forward lower lobe cargo compartment and one third is distributed to the cabin
pack 3 remains in high flow during cruise
with the LLCCAFR in both low
2/3rds of pack three air is distributed to the forward lower lobe cargo compartment and one third to the cabin
all pack remain in high flow during cruise
with the LLCCAFR selector in OFF or AFT what happens to the forward lower lobe cargo compartment? what happens to that air?
conditioned air to the forward lower lobe cargo compartment is shut off all pack three air is distributed to the cabin
the cargo exhaust system discharges the air to prevent odors from migrating into the cabin. the flight exhaust system discharges the air overboard through the overboard valve on the fuselage side skin
Where does the aft lower lobe cargo compartment get its air?
Pack 2
what controls the volume of air to the after lower lobe cargo compartment??
LLCCAFR selector
with the LLCCAFR selector in aft hi what happens?
all pack two air is distributed to aft lower lobe cargo
all packs Remian in high flow during cruise
with the LLCCAFR selector in aft low what happens
pack two air is distributed to both aft lower lobe cargo and the cabin
pack two remains in high flow during cruise
with the LLCCAFR selector in OFF or FWD what happens to the aft lower lobe cargo compartment? what happens to that air?
conditioned air to the aft lower lobe cargo compartment is shut off, all pack 2 air is distrusted to the cabin
with the LLCCAFR selector in both low what happens
pack two air is distributed to both after lower lobe cargo and the cabin
all packs remain in high flow during cruise
zone temps are controlled how?
zone temp controllers
with the LLCCAFR selector in off what zone controlls pack outlet temp?
the zone requiring the coolest temperature
If the LLCCAFR selector is in FWD HI what happens to the pack outlet temps
pack 3 outlet temp is controlled to maintain forward lower lobe temp.
the coolest of flight deck/upper deck/crew rest/ main deck requested temps control pack outlet temp for pack 1 and 2.
If the LLCCAFR selector is in AFT HI what happens to the pack outlet temps
pack 2 outlet temp is controlled to maintain aft lower lobe cargo compartment commanded temperature.
the coolest of flight deck/upper deck/crew rest/ main deck requested temps control pack outlet temp for pack 1 and 3.
if the LLCCAFR selector is in low what does the ZTC do regarding pack outlet temperature?
it limits pack outlet temperature of the pack supplying the selected lower lobe cargo compartment to be not higher than the pack outlet temp of the other two packs. the ZTC regulates the temp of the selected lower lobe cargo compartment by; closing the trim modulating valve and supplying cooler air from the pack supplying conditioned air to the compartment or modulating the cargo trim air valve to supply warmer conditioned air.
When is trim air not available to the flight deck upper deck crew rest main deck?
TEMP ZONE displayed on EICAS
the center section of the bleed duct is isolated
TRIM AIR OFF is displayed
or
MASTER Trim Air Switch is OFF
What happens if to the flight deck / upper deck / crew rest / main deck if trim air is not available?
if the flight deck temp selector setting is avilable to ptc, pack outlet temp of all packs is regulated to achieve an average between 65-85F. or
if flight deck temp selector setting is unavailable to the PTC, pack outlet temp is regulated to achieve the last flight deck temp set
or if the last flight temp is unavailable to the PTC, pack outlet temp is regulated to 75
when is trim air not available to the aft lower lobe cargo?
center section of the bleed duct is isolated or
EICAS temp zone due to lower aft zone duct overheat or
for ztc fault that causes that aft forward to trim air valve to close
when is trim air not available to the forward lower lobe cargo?
center section of the bleed duct is isolated or
EICAS temp zone due to lower forward zone duct overheat or
for ztc fault that causes that lower forward to trim air valve to close
if trim air is not available to the lower forward or aft how does the back up mode control temperature?
if the forward or aft lower temp setting is available to the PTV pack 3 (pack 2 for aft) is regulated to the achieve the temperature set by the selector or
if the forward or aft lower temp setting is not aviable to the PTC, pack 3 (pack 2 for aft) is regulated to achieve the cargo temp sensed at the time backup mode was initiated or
if forward or aft lower lobe cargo temp is unavailable to the PTC, pack 3 (pack 2 if aft) is controlled to the pack outlet temp senses at the time back up mode was intiated.
if a system fault or overheat occurs in the flight deck, upper deck, crew rest, or main deck, what happens to the trim air?
master trim air closes and backup ,mode controls cabin temp
if a system fault or overheat occurs in lower cargo what happens?
cargo zone trim air shutoff valve closes and a back up mode controls temperature.
how would you reset the cargo air trim shutoff valve?
position the cargo temp selector from auto to man or from man to auto, positioning LLCCAFR selctor to off does the same thing.
What heats the forward Cargo?
exhaust from the E/E
what heats the aft cargo?
bleed air from the center section of the bleed air duct. a thermal switch in the compartment opens and closes the temp control valve. an overheat thermal switch provides overheat protection
What are 3 possibilities for the E/E exhaust air?
Forward cargo, closed loop (cool temps), overboard (hot temps)
When does the E/E configure for flight?
no engines running on the ground when its cold. 1 or more engines on the ground running. position the selector to stby
What is flight configuration for E/E (freighter)
dependent on the LLCCAFR selector and forward LLcargo temp selector; colder than 50 degrees LLCCAFR in FWD low/high or both low, inboard exhuast valve is closed, goes to closed loop. warmer than 50 and the inboard exhaust valve is open
when is conditioned air from the packs directed into te lfight deck electrical equipment?
when two or 3 packs operating
how is cabin pressurization controlled?
2 outflow valves located near the rear of the cabin, they operate in Parrell
how many cabin altitude controllers?
2, A and B, each controller controls both outflow valves
what protects the aircraft against excessive pressure differential?
positive and negative relief vales
how do the cabin altitude controllers calculate a pressurization schedule?
FMC flight plan data and ambient pressure
how many positive pressure relief valves are there?
two mechanical prevent over pressurization
if cruise altitude is unavailable from the FMC in AUTO what does the cabin altitude controller assume for ALT?
FL390
where are the negative pressure relief valves located?
side cargo door
In the event of over pressurization what happens?
pThe positive pressure relief valves open and pack 2 will shuts down to assist in relieving excess pressure
where is engine bleed air supplied from?
from either the IP or HP engine sections. IP section during high power settings, HP for lower power settings.
What limits bleed air pressure?
the PRV
What regulates bleed air temperature?
fan air Precooler
when does a engine bleed air valve close?
when a ground cart is supply air
if a bleed air over temperature occurs
if a bleed air over pressure occurs
if a bleed source loss occurs
if a blee air duct leak occurs
when an engine fire switch is pulled
if the engine start valve fails to close what happens?
the respective engine nacelle anti ice is not available
what happens if the engine bleed air switch is off?
the respective engine bleed air valve and prv and HO bleed valved are closed/
if a bleed air overheat is detected what happens?
the PRV and and HP blled vavles close.
bleed air is available for nacelle anti ice operation with the engine bleed air switch on except when?
start valve is not closed
PRV has failed closed
PRV has been closed due to a bleed air overheat
bleed air is not available for nacelle anti ice operation with the engine bleed air switch off except when?
start valve is not closed
PRV has failed closed
PRV has been closed due to a bleed air overheat
the HP bleed valve is failed open
bleed air is available for thrust reverser operation with the engine bleed air switch either on or off except when
prv has failed closed or prv has been closed due a bleed air overheat or start valve is not closed.
where is apu bleed air supplied to?
the center section of the bleed air dct.
what prevents reverse flow of bleed air to the apu?
a check valve
if the apu shuts down for an overheat can it be restarted?
no
how is a duct leak or overheat detected?>
by the bleed duct overheat system, if detected it can be isolated by closing the respective isolation and engine bleed air valves.
if the center duct is isolated, what does pushing the AFT cargo heat switch off do?
closes the electrically operated aft cargo heat valves to prevent cabin air flowing in reverse through the aft cargo heat supply duct and into the leaking center duct. all temp zones operate in back up mode since trim air wouldn’t be available. potatable water pressurization and cargo smoke detection are not available.
if the left or right duct is isolated what happens?
the respective leading-edge flaps operate in secondary mode
