Systems Knowledge

Question 1

AIR SYSTEMS

Question 2

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.

Answer 2

2 packs deliver pressurised conditioned air to cabin
Outflow valve modulates letting air overboard to control cabin pressure

Question 3

Where is air taken from at the engine ?

Answer 3

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 *

Question 4

What may cause BLEED TRIP OFF LIGHT ?

Answer 4

Over temp 254 degrees

Over pressure 220psi

valve automatically closes to prevent damage to the duct

Question 5

What will cause a WING BODY OVERHEAT ?

Answer 5

A bleed air leak, which could cause damage to aircraft structures.

Needs 115V AC to operate this warning

DO NOT USE WING ANTI ICE

Question 6

How does the air conditioning process work?

Answer 6

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

Question 7

When will a PACK light illuminate ?

Answer 7

Trip off (overheat) or Failure of pack controller

Overheat conditions in -
- ACM COMP
- ACM TURBINE
- PACK DISCHARGE

Question 8

When will HIGH FLOW PACK occur when in AUTO?

Answer 8

Single pack operation with flaps up in flight

Single pack operation with APU bleed air on and both bleeds OFF

Question 9

Temp controls and TRIM AIR

Answer 9

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.

Question 10

Equipment Cooling

Answer 10

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

Question 11

Where is the pressurisation outflow valve located ?

Answer 11

Below right hand horizontal stab

Question 12

When there is a total loss of AC power, pressurisation has to be controlled manually.

Due to DC BUS 1 & 2 not been powered.

Answer 12

As above

Question 13

OFF SCHEDULE DESCENT

Answer 13

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

Question 14

Pressurisation MAN MODE

Answer 14

Operated at a faster rate than AUTO. Full valve deflection takes approx. 20 seconds.

MAN operation powered from BAT BUS

Question 15

As per BOEING BULLETIN what is considered Uncontrollable in terms of Pressurisation?

Answer 15

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)

Question 16

HYDRAULICS

A
B
STBY

Question 17

HYD PRESSURE - 2800 - 3500 (NORM - 3000)

ELEC - WHEEL WELL
ENGINE - GEAR BOX

Question 18

HYD A & B RES ARE PRESSURISED BY BLEED AIR TO ALLOW POSITIVE PRESSURE AND PREVENT CAVITATION AND FOAMING.

Question 19

STBY SYSTEM IS CONNECTED TO HYD B SYSTEM FOR PRESSURISATION AND SERVICING

Question 20

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

Question 21

EMDP is electrically driven from the opposite side for redundancy.

EMDP has 6 times lower output than EDP.

Answer 21

EMDP HYD A = XFR BUS #2

EMDP HYD B = XFR BUS #1

Question 22

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

Question 23

HYD A RES - has a standpipe up to first 20% of the reservoir.

Leak is more prone in the EDP.

Answer 23

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.

Question 24

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

Answer 24

STBY HYD systems is serviced through HYD B system

When a leak occurs in STBY SYS, HYD B QTY will drop to 70%

Question 25

SYS B HYD has larger QTY I’m guessing for STBY operations included

Question 26

PTU - allows HYD A pressure to power flaps, slats and leading edge devices in the case of HYD B failure without any fluid exchange.

Answer 26

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)

Question 27

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)

Answer 27

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

Question 28

STBY HYD SYS -

-STBY RUDDER
- STBY YAW DAMPER
- LE FLAPS AND SLATS (EXTENSION ONLY)
- THRUST REVERSERS

Answer 28

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%)

Question 29

FUEL SYSTEM

Question 30

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.

Question 31

Water scavenge pumps are suction operated and remove water from bottom of tanks.

Question 32

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.

Question 33

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)

Question 34

NGS - converts bleed air from left side to nitrogen enriched air to stop possible ignition of Vapor in centre tank.

Question 35

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

Question 36

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.

Question 37

L IGN -
R IGN -

Answer 37

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

Question 38

CONT VS FLT

Answer 38

CONT - provides ignition from selected igniter (until N2 less than idle with fuel in)

FLT - provides ignition from BOTH igniters regardless