Systems Knowledge Flashcards
AIR SYSTEMS
Outside air pressurised by engines or APU, and then used for pressurisation and air conditioning. This air must be cooled by the packs before entering the cabin via mic manifold.
2 packs deliver pressurised conditioned air to cabin
Outflow valve modulates letting air overboard to control cabin pressure
Where is air taken from at the engine ?
Low power conditions = 9th stage (27% - 47% N1)
High power conditions 5th stage (> 47% N1)
*high stage bleed valve fail to close at high power settings may result in BLEED TRIP OFF *
What may cause BLEED TRIP OFF LIGHT ?
Over temp 254 degrees
Over pressure 220psi
valve automatically closes to prevent damage to the duct
What will cause a WING BODY OVERHEAT ?
A bleed air leak, which could cause damage to aircraft structures.
Needs 115V AC to operate this warning
DO NOT USE WING ANTI ICE
How does the air conditioning process work?
Bleed air received from engine
Divided into COOLING CYCLE OR COOLING BYPASS
COOLING CYCLE - enters Primary Heat exchanger - cooled then sent to Air Cycle Machine (ACM) which compresses the air (therefore heating up again) then heads to Secondary Heat Exchanger - cooled again then ACM turbine where the air is cooled further due expansion.
ON GROUND RAM AIR PROVIDES COOLING TO HEAT EXCHANGER. In flight bypassed
When will a PACK light illuminate ?
Trip off (overheat) or Failure of pack controller
Overheat conditions in -
- ACM COMP
- ACM TURBINE
- PACK DISCHARGE
When will HIGH FLOW PACK occur when in AUTO?
Single pack operation with flaps up in flight
Single pack operation with APU bleed air on and both bleeds OFF
Temp controls and TRIM AIR
18 - 30 degrees
TRIM AIR - Will regulate the temp if needed higher than the actual output of the Pack temp for each zone as required.
Equipment Cooling
Cooling provided for Avionics. Cool air drawn through and dumped overboard or the warm exhaust air is used to warm FWD cargo compartment.
NORM/ALT
OFF light indicated insufficient airflow, and can signal impending pressurisation issues.
OFF light should extinguish within 5 seconds of selecting ALT
Where is the pressurisation outflow valve located ?
Below right hand horizontal stab
When there is a total loss of AC power, pressurisation has to be controlled manually.
Due to DC BUS 1 & 2 not been powered.
As above
OFF SCHEDULE DESCENT
This will illuminated if descent is commenced prior to reaching set CRZ ALT. This will discreetly amend Landing ALT to departure port in the idea of an air return.
Extinguish if - CRZ ALT changed to current
- ACFT Climbs
- MAN Mode
- ACFT lands
Pressurisation MAN MODE
Operated at a faster rate than AUTO. Full valve deflection takes approx. 20 seconds.
MAN operation powered from BAT BUS
As per BOEING BULLETIN what is considered Uncontrollable in terms of Pressurisation?
Cabin Rate exceeds 750fpm in AUTO or ALTN mode
Cabin Rate can not be controlled manually (Rate of change)
CABIN ALT exceeds 15,000ft (too long to get back to 10,000ft)
HYDRAULICS
A
B
STBY
HYD PRESSURE - 2800 - 3500 (NORM - 3000)
ELEC - WHEEL WELL
ENGINE - GEAR BOX
HYD A & B RES ARE PRESSURISED BY BLEED AIR TO ALLOW POSITIVE PRESSURE AND PREVENT CAVITATION AND FOAMING.
STBY SYSTEM IS CONNECTED TO HYD B SYSTEM FOR PRESSURISATION AND SERVICING
HYD LOW PRESS LIGHT - DROPS BELOW 1300PSI
EDP LOW PRESS light is deactivated if fire switch is pulled
STBY LOW PRESS is only armed if the stby system is manually or automatically activated
EMDP is electrically driven from the opposite side for redundancy.
EMDP has 6 times lower output than EDP.
EMDP HYD A = XFR BUS #2
EMDP HYD B = XFR BUS #1
Fuel provided cooling to the heat exchangers for HYD fluid.
MIN 760kg in each respective main tank on ground for cooling.
Main tank no.1 = SYS A
Main tank no.2 = SYS B
HYD A RES - has a standpipe up to first 20% of the reservoir.
Leak is more prone in the EDP.
EDP line - Res QTY will decrease to 20% if leak - EMDP will provide pressure with remaining 20%
EMDP - Res QTY will decrease to 0% if leak.
HYD B RES - Has common standpipe between EDP and EMDP
If leak occurs 5L will remain in reservoir which can be used for PTU operations
STBY HYD systems is serviced through HYD B system
When a leak occurs in STBY SYS, HYD B QTY will drop to 70%
SYS B HYD has larger QTY I’m guessing for STBY operations included
PTU - allows HYD A pressure to power flaps, slats and leading edge devices in the case of HYD B failure without any fluid exchange.
AUTO operations occurs when -
- Airborne
- B EDP pressure drops below 2350psi
- Flaps are not UP (SFP)
- Flaps are less than 15 but not up (non SFP)
LGTU ( LDG GEAR TFR UNIT)
System designed to raise the gear at a normal rate after EDP A volume is lost (ENGINE NO.1 FAIL)
HYD B is used to retract the LDG GEAR when the following is true -
- Airborne
- LDG GEAR HDNLE UP POS
- No. 1 engine RPM drops below limit (N2 < 50%)
- Either main gear is not up and locked
STBY HYD SYS -
-STBY RUDDER
- STBY YAW DAMPER
- LE FLAPS AND SLATS (EXTENSION ONLY)
- THRUST REVERSERS
MAN OPERATION - FLT CONTR switches to STBY RUDDER
AUTO OPERATION - occurs when HYD A & B pressure are lost together and:
- Airborne
- Flaps extended
- FLT CONTR switches are in ON position.
LOW QTY light - always armed (illuminated QTY less than 50%)
FUEL SYSTEM
Main tanks are split via wing ribs. There is a valve that lets fuel flow toward centre of ACFT but not the other way.
Main tanks have one SURGE PUMP where overflow fuel is collected and returned to main tank when able. However if surge tank is full it will dispose of this fuel overboard through wing fuel vent.
Water scavenge pumps are suction operated and remove water from bottom of tanks.
Centre tank pumps have higher output (23psi) so all pumps on, centre fuel used first. Main tank pumps = (10psi).
When AC transfer bus loses PWR, fuel from centre tank cannot be used.
Centre tank fuel pumps have auto shutoff after 15 secs of LOW PRESS lights illuminating.
FUEL LOW - @453kg will stay illuminated until above 567kg
FUEL CONFIG - illuminates to tell crew useable fuel in centre tank not been used. (>726kg)
NGS - converts bleed air from left side to nitrogen enriched air to stop possible ignition of Vapor in centre tank.
Suction feed - from each main tank is available, but degraded fuel flow above FL130 is possible. Maintain low ROC nose up pitch and action QRH.
At high altitude, suction will be low
Centre tank Scavenge pump -
Operate when Tank 1 FWD pump is on and Tank 1 is half full. Flow rate from centre tank to Tank 1 is 100-200kg per hour.
L IGN -
R IGN -
L IGN - powered from Onside TFS BUS (ENG 1 = XFR#1)
R IGN - powered from AC standby BUS
for cold temp first start of day above 2000’AGL consider selecting BOTH
CONT VS FLT
CONT - provides ignition from selected igniter (until N2 less than idle with fuel in)
FLT - provides ignition from BOTH igniters regardless
