Chapter 2 Air systems Flashcards
What will cause a BLEED TRIP OFF Light?
If the engine bleed air temperature OR pressure has been exceeded.
(FCOM 2.20.1)
What will cause a ‘PACK TRIP OFF’ light to illuminate?
Respective pack has exceeded temperature limits and has tripped off
What does amber ‘EQUIPMENT COOLING OFF’ Light indicate?
Loss of airflow due to failure of an equipment cooling fan.
There is no airflow detected coming from the respective cooling exhaust
(FCOM 2.31.7)
How many packs are required to maintain pressurisation up to FL410 ?
A single pack IN HIGH flow is capable of maintaining pressurization up to the maximum certified ceiling.
When the aircraft is on the ground or the flaps are down with the packs in AUTO, will the packs still automatically change to high flow, if operating on one pack only?
No, automatic switching to high air flow is inhibited in this situation to ensure adequate engine power is available for single engine operations.
What is the purpose of operating the packs in AUTO during normal operations in flight?
Incase one pack stops supplying air, the remaining pack automatically switches to high air flow to increase ventilation.
What is is the purpose of the Ram Air System?
Provides cooling air for the heat exchangers.
How is the Ram Air System controlled and operated?
The system is automatically controlled by the packs through the operation of the ram inlet doors.
What are the four steps of the cooling cycle?
- Bleed air passes through heat exchanger for cooling.
- Air then flows to Air Cycle Machine for refrigeration and water separation.
- The cold air is then ‘conditioned’ and combined with hot air.
- The conditioned air is then distributed by the mix manifold.
What happens to the Air Mix valves if the pack valves close and why?
The air mix valves drive to full cold position in order to aid startup of the cooling cycle and prevent hot air trips when the packs are turned back on.
What is the purpose of the Recirculation fans?
To reduce engine bleed air demand and air conditioning system pack load.
What happens to the Equipment cooling exhaust fan if there is a Forward Cargo Fire warning?
The equipment cooling exhaust fan SHUTS OFF, and the ‘OFF’ light is inhibited.
How many automatic cabin pressure controllers are fitted to INU?
Two
How is the pressurisation controlled?
By modulating the outflow and overboard exhaust valve.
What is the purpose of the PRESSURE RELIEF VALVES?
To provide safety pressure relief incase the cabin differential pressure EXCEEDS 9.0 PSI.
What is the maximum cabin differential pressure?
9.1PSI
How many pressure relief valves are there and what are they called?
Two, a pressure relief and one negative relief valve.
Where do BOTH the Cabin Pressure controllers receive their altitude and pressure data from?
ADIRU’s, which receives barometric corrections from the BARO reference selectors (QNH)
Why does the outflow valve modulate towards ‘closed’ position when thrust is increased during the take off roll?
Ground pressurization of the cabin makes the transition to pressurized flight more gradual for the passengers, and also gives the system better response to ground effect pressure changes during takeoff.
What are the pressurisation controllers programmed to do if the amber ‘OFF SCHED DESCENT’ light illuminates?
The controller programs the cabin to land at the takeoff field elevation without further pilot inputs. (Assumes return 4 landing)
What happens if the FLT ALT indicator is changed, after an amber ‘OFF SCHED DESCENT’ light illuminates?
The automatic abort capability to the original takeoff field elevation is lost.
What happens if the FLT ALT indicator is changed, after an amber ‘OFF SCHED DESCENT! light illuminates?
The automatic abort capability to the original takeoff field elevation is lost.
What triggers pressurisation to change from climb, cruise or descend mode?
When the airplane climbs or descends to within/outside of 0.25 psi of the selected FLT ALT.
When is manual control of the cabin altitude required?
If both the AUTO and ALTN modes are inoperative or during a non-normal situation.
How is the pressurisation controlled when in Manual mode?
By manually positioning the outflow valve using the Outflow Valve switch.
DELETE
How should the outflow valves be treated when manually opening or closing the valve?
A very small movement of the outflow valve is recommended at one time.
A small movement of the outflow valve can cause a large change in cabin rate of climb or descent. Manual actuation of the outflow valve can produce large, rapid changes in cabin pressure which could result in passenger and crew discomfort and/or injury.
Is Pre conditioned air delivered directly to the LEFT, RIGHT or MIX manifold?
MIX MANIFOLD
With the Isolation valve in ‘AUTO’, what is the expected normal position of the valve and what will change this?
CLOSED, if any of the bleed or packs switches are placed ‘OFF’ (This action will open valve).
Note: The valve should normally be closed, however if one of the sides l
(FCOM 2.20.2)
If the ‘WING BODY OVER HEAT’ lights up, which side (L or R) indicates a bleed air duct leak from the APU?
LEFT (FCOM 2.10.3)
Note: The KEEL BEAM and APU BLEED DUCT has a sensor.