pressurisation systems Flashcards
OXYGEN REQUIREMENTS
at sea level, the atmospheric pressure is __.7psi (__.29Nscm) the partial pressure of the oxygen in the air is psi (.1Nscm)
OXYGEN REQUIREMENTS
at sea level, the atmospheric pressure is 14.7psi (10.29Nscm) the partial pressure of the oxygen in the air is 3psi (2.1Nscm)
ANOXIA
is the ________ absence of oxygen in the blood
ANOXIA
is the COMPLETE absence of oxygen in the blood
HYPOXIA
hypoxia in which there is complete deprivation of oxygen supply is referred to as ________
HYPOXIA
hypoxia in which there is complete deprivation of oxygen supply is referred to as ANOXIA
ALTITUDE SICKNESS
passengers may experience fati___, nau___, head_____, sleep________, and (on extended flights) pulmonary ______
ALTITUDE SICKNESS
passengers may experience fatiGUE, nauSEA, headACHES, sleepLESSNESS, and (on extended flights) pulmonary OEDEMA
BAROTRAUMA
the most common problems occur with air trapped in the ______ ear (aerotitus) or __________ sinuses by a blocked _________ tube or sinuses
BAROTRAUMA
the most common problems occur with air trapped in the MIDDLE ear (aerotitus) or PARANASAL sinuses by a blocked EUSTACHIAN tube or sinuses
RATE OF CHANGE OF CABIN ALTITUDE
it has been established that a rate of change of altitude of ___ feet per minute (1.1nN/sqm per minute in terms of pressure change) is an acceptable limit for pressurised passenger aircraft
experience has shown that the vast majority of people suffer no discomfort due to anoxia at altitudes up to _____ ft, and this is a generally accepted safe figure which has been widely adopted as the cabin _______ limit for use in pressurised passenger aircraft
RATE OF CHANGE OF CABIN ALTITUDE
it has been established that a rate of change of altitude of 300 feet per minute (1.1nN/sqm per minute in terms of pressure change) is an acceptable limit for pressurised passenger aircraft
experience has shown that the vast majority of people suffer no discomfort due to anoxia at altitudes up to 8000 ft, and this is a generally accepted safe figure which has been widely adopted as the cabin ALTITUDE limit for use in pressurised passenger aircraft
AIR SUPPLY AND VENTILATION
when the human body is making its maximum oxygen demand, 0.__ cubic feet (0.025 cubic metres) of oxygen are required per minute.
this amount of oxygen is contained in 12.__ cubic feet (0.36 cubic meters) of air
since there are 13.2 cubic feet (0.37 cubic meters) of air in one pound of air at sea level, it is desirable for pressurised passenger aircraft, that the air conditioning should supply one pound (0.__kg) of air per _______ per ______ into the cabin
note: in an __________, a minimum of 0._ pounds per person per minute must apply
AIR SUPPLY AND VENTILATION
when the human body is making its maximum oxygen demand, 0.92 cubic feet (0.025 cubic metres) of oxygen are required per minute.
this amount of oxygen is contained in 12.85 cubic feet (0.36 cubic meters) of air
since there are 13.2 cubic feet (0.37 cubic meters) of air in one pound of air at sea level, it is desirable for pressurised passenger aircraft, that the air conditioning should supply one pound (0.45kg) of air per PERSON per MINUTE into the cabin
note: in an EMERGENCY, a minimum of 0.5 pounds per person per minute must apply
HUMIDITY
the humidity of the air in the cabin should be maintained at around __%
HUMIDITY
the humidity of the air in the cabin should be maintained at around 30%
PRESSURISATION CONTROL AND OPERATION. MASS FLOW CONTROL
the amount of air supplied for cabin ___________ requires to be _________ so that a constant mass flow passes to the cabin
this is to prevent pressure ______ and in order to maintain an adequate amount of air to meet normal _________, conditioning and pressurisation requirements
PRESSURISATION CONTROL AND OPERATION. MASS FLOW CONTROL
the amount of air supplied for cabin PRESSURISATION requires to be CONTROLLED so that a constant mass flow passes to the cabin
this is to prevent pressure SURGES and in order to maintain an adequate amount of air to meet normal VENTILATION, conditioning and pressurisation requirements
PRESSURISATION CONTROL
_______ of cabin pressure and rate of ______ of cabin pressure is obtained by regulating the rate at which this air _______ from the cabin to atmosphere
PRESSURISATION CONTROL
CONTROL of cabin pressure and rate of CHANGE of cabin pressure is obtained by regulating the rate at which this air ESCAPES from the cabin to atmosphere
POSITIVE DIFFERENTIAL PRESSURE
the condition in an aircraft where the pressure in the cabin is _______ than local atmospheric pressure is defined as a _______ pressure differential
positive differential pressure is normally controlled by the cabin pressure ________ in conjunction with the _______ valve
although the complete pressure control system is rarely duplicated on modern aircraft, the requirement is met by ________ certain ________ parts of the pressure control system, or by using a cabin ______ valve
POSITIVE DIFFERENTIAL PRESSURE
the condition in an aircraft where the pressure in the cabin is GREATER than local atmospheric pressure is defined as a POSITIVE pressure differential
positive differential pressure is normally controlled by the cabin pressure CONTROLLER in conjunction with the OUTFLOW valve
although the complete pressure control system is rarely duplicated on modern aircraft, the requirement is met by DUPLICATING certain ESSENTIAL parts of the pressure control system, or by using a cabin SAFETY valve
NEGATIVE DIFFERENTIAL PRESSURE
owing to the tendency for the aircraft cabin to be ______, it is limited to maximum value of 0._psi (3.45KN/sqm) by means of duplicated _______ relief valves
NEGATIVE DIFFERENTIAL PRESSURE
owing to the tendency for the aircraft cabin to be CRUSHED, it is limited to maximum value of 0.5psi (3.45KN/sqm) by means of duplicated INWARD relief valves
TYPICAL PRESSURISATION SYSTEM USING PNEUMATIC CONTROL
in the event of one air conditioning pack _______, the remaining pack is usually ________ of maintaining pressured flight
TYPICAL PRESSURISATION SYSTEM USING PNEUMATIC CONTROL
in the event of one air conditioning pack FAILING, the remaining pack is usually CAPABLE of maintaining pressured flight
TYPICAL PRESSURISATION SYSTEM OPERATION
before take off, the desired cabin altitude is set on the pressure _________, the dial being graduated between minus _000ft and plus _000ft
the rate of ______ control is set to govern the speed at which the _____ altitude changes
the dial is graduated decrease - increase, the range being from _00 feet per minute to __00 feet per minute with the normal setting representing approximately _00 feet per minute rate of change
also, prior to the off, the dump valve is normally _____
the discharge valves at this stage are kept in the ____ position by ___ pressure provided by an ejector
each discharge valve is is normally provided with a ___________ solenoid
the solenoids are energised when the ___ switches are in the weight on position, opening the discharge valves
on take-off, the discharge valves _____ and the air conditioning packs are selected __
this will bring the pressurisation system into _________ and pressure within the cabin will be controlled to maintain the pre-set cabin altitude
TYPICAL PRESSURISATION SYSTEM OPERATION
before take off, the desired cabin altitude is set on the pressure CONTROLLER, the dial being graduated between minus 1000ft and plus 8000ft
the rate of CHANGE control is set to govern the speed at which the cabin altitude changes
the dial is graduated decrease - increase, the range being from 100 feet per minute to 1200 feet per minute with the normal setting representing approximately 300 feet per minute rate of change
also, prior to the off, the dump valve is normally CLOSED
the discharge valves at this stage are kept in the OPEN position by LOW pressure provided by an ejector
each discharge valve is is normally provided with a DEPRESSURISING solenoid
the solenoids are energised when the WOW switches are in the weight on position, opening the discharge valves
on take-off, the discharge valves CLOSE and the air conditioning packs are selected ON
this will bring the pressurisation system into OPERATION and pressure within the cabin will be controlled to maintain the pre-set cabin altitude
PRESSURISATION SYSTEM COMPONENTS\
typical pressurisation system components are:
- pressure _________
- discharge (_______ valve)
- cabin ______ valves
- cabin ____ out panels
PRESSURISATION SYSTEM COMPONENTS\
typical pressurisation system components are:
- pressure CONTROLLER
- discharge (OUTFLOW valve)
- cabin SAFETY valves
- cabin BLOW out panels
DISCHARGE (OUTFLOW) VALVE
the discharge valve may fulfil the multiple function of ________ valve, ______ valve and inwards ______ valve
DISCHARGE (OUTFLOW) VALVE
the discharge valve may fulfil the multiple function of DISCHARGE valve, SAFETY valve and inwards RELIEF valve
OPERATION OF INWARD RELIEF VALVE
should the ambient pressure ______ the cabin pressure, for example by 0._psi, this negative pressure differential, acting across the ______ diaphragm, causes the entire inner mechanism to lift
this allows _______ air to enter the cabin and ________ pressures
OPERATION OF INWARD RELIEF VALVE
should the ambient pressure EXCEED the cabin pressure, for example by 0.5psi, this negative pressure differential, acting across the LOWER diaphragm, causes the entire inner mechanism to lift
this allows AMBIENT air to enter the cabin and EQUALISE pressures
TYPICAL PRESSURISATION SYSTEM. CABIN PRESSURE CONTROLLER
before taking off the desired cabin altitude is set on the ________ controller
at the same time, the rate of ______ control is set to govern the speed of change of cabin altitude
during take off, the ________ valves will be open
after take off, these will be _____ and the cabin will tend to increase pressure relative to ambient pressures
the rate of ________ change will depend of the rate of change setting and to a degree on the ________ of the aircraft climb
normally the aircraft rate of _____ exceeds the controlled rate of ______ setting and the cabin altitude alters more ______ than the aircraft altitude
the ideal is when the aircraft rate of climb is adjusted to arrive at the selected flight altitude slightly _____ the cabin reaches the height selected on the pressure controller, thus giving a ______ pressure change with no abrupt pressure variations
before landing, the air conditioning packs are selected ___. on landing, the discharge valves are opened as the de-pressurising solenoids are energised by the ___ switches. this relieves any residual differential pressure in the cabin. the ____ valve is then selected open
TYPICAL PRESSURISATION SYSTEM. CABIN PRESSURE CONTROLLER
before taking off the desired cabin altitude is set on the pressure controller
at the same time, the rate of change control is set to govern the speed of change of cabin altitude
during take off, the discharge valves will be open
after take off, these will be closed and the cabin will tend to increase pressure relative to ambient pressures
the rate of pressure change will depend of the rate of change setting and to a degree on the rapidity of the aircraft climb
normally the aircraft rate of climb exceeds the controlled rate of change setting and the cabin altitude alters more slowly than the aircraft altitude
the ideal is when the aircraft rate of climb is adjusted to arrive at the selected flight altitude slightly after the cabin reaches the height selected on the pressure controller, thus giving a smooth pressure change with no abrupt pressure variations
before landing, the air conditioning packs are selected off. on landing, the discharge valves are opened as the de-pressurising solenoids are energised by the WOW switches. this relieves any residual differential pressure in the cabin. the dump valve is then selected open
MAX PRESSURE DIFFERENTIAL
should the aircraft climb above the maximum pressure altitude as set on the ___________, then the system will no longer hold the set cabin altitude. this is because the maximum __________ pressure cannot be __________ and so the cabin altitude will _________ at the same rate as the aircraft altitude increases, once the max pressure differential is reached.
it is therefore desirable that the maximum flight altitude does not _______ the figure shown on the dial of the pressure _________ in order to preserve passenger comfort
during the climb, the ___ discharge valves will be opening and closing in response to signals from the pressure controller. cabin air is allowed to exhaust via the discharge valves a slightly ______ rate than it is being supplied by the blowers. this allows the pressure within the cabin to _________ relative to airfield pressure but to increase relative to the _______ pressure as the aircraft climbs. this condition will exist until the cabin altitude reaches the controller setting when conditions will stabilise and the discharge valves will open and close to maintain the pressure equivalent to that particular controller setting (_________ CONTROL)
MAX PRESSURE DIFFERENTIAL
should the aircraft climb above the maximum pressure altitude as set on the CONTROLLER, then the system will no longer hold the set cabin altitude. this is because the maximum DIFFERENTIAL pressure cannot be EXCEEDED and so the cabin altitude will INCREASE at the same rate as the aircraft altitude increases, once the max pressure differential is reached.
it is therefore desirable that the maximum flight altitude does not EXCEED the figure shown on the dial of the pressure CONTROLLER in order to preserve passenger comfort
during the climb, the TWO discharge valves will be opening and closing in response to signals from the pressure controller. cabin air is allowed to exhaust via the discharge valves a slightly HIGHER rate than it is being supplied by the blowers. this allows the pressure within the cabin to DECREASE relative to airfield pressure but to increase relative to the OUTSIDE pressure as the aircraft climbs. this condition will exist until the cabin altitude reaches the controller setting when conditions will stabilise and the discharge valves will open and close to maintain the pressure equivalent to that particular controller setting (ISOBARIC CONTROL)
PRESSURISATION SYSTEM PROTECTION
the differential _______ in the pressure __________ ensures that the max pressure differential is not exceeded
should the complete system fail, a cabin ______ valve on the rear pressure bulkhead will relieve at a slightly ______ pressure than the discharge valve protection
the discharge valves are set to inward vent at a negative differential pressure of 0._psi
PRESSURISATION SYSTEM PROTECTION
the differential CAPSULE in the pressure CONTROLLER ensures that the max pressure differential is not exceeded
should the complete system fail, a cabin SAFETY valve on the rear pressure bulkhead will relieve at a slightly HIGHER pressure than the discharge valve protection
the discharge valves are set to inward vent at a negative differential pressure of 0.5psi
CABIN INDICATIONS AND WARNINGS
a cabin altitude warning _____ is also fitted to the instrument panel to indicate when the cabin altitude reaches and exceeds __000ft
CABIN INDICATIONS AND WARNINGS
a cabin altitude warning LIGHT is also fitted to the instrument panel to indicate when the cabin altitude reaches and exceeds 10000ft
PRE PRESSURISATION
where ___ pressurisation of the cabin prior to take off is part of the pressurisation schedule, the pressure controller will require inputs from the:
- _______ gear (wow)
- engine ___ pressure
- forward ________ position
- ____ warning system
the cabin pressure within this part of the schedule is normally only marginally _____ the ambient pressure (i.e. cabin altitude slightly _____ airfield)
if the outflow valve moved to the closed position at ____ off, (as in the ____________ controlled system) the aircraft would be well into the climb before the cabin pressurisation system was __________ and the correct rate of _____ established
this would cause ___________ to the passengers
pre pressurisation ensures that the cabin pressure controller and the outflow valve have stabilised and can enter the cabin into the predetermined climb rate ___________ after the aircraft takes off
PRE PRESSURISATION
where PRE pressurisation of the cabin prior to take off is part of the pressurisation schedule, the pressure controller will require inputs from the:
- LANDING gear (wow)
- engine OIL pressure
- forward THROTTLE position
- DOOR warning system
the cabin pressure within this part of the schedule is normally only marginally ABOVE the ambient pressure (i.e. cabin altitude slightly BELOW airfield)
if the outflow valve moved to the closed position at TAKE off, (as in the PNEUMATICALLY controlled system) the aircraft would be well into the climb before the cabin pressurisation system was STABILISED and the correct rate of CLIMB established
this would cause DISCOMFORT to the passengers
pre pressurisation ensures that the cabin pressure controller and the outflow valve have stabilised and can enter the cabin into the predetermined climb rate IMMEDIATELY after the aircraft takes off
LANDING
for those aircraft which are designed to land in a pressurised condition, the cabin altitude controller will normally ____________ lower the selected landing field by approximately ___ft landing height
LANDING
for those aircraft which are designed to land in a pressurised condition, the cabin altitude controller will normally AUTOMATICALLY lower the selected landing field by approximately 100ft landing height
TESTING OF PRESSURISATION SYSTEMS. TEST PREP
- all persons in the cabin must be _________ fit
- a minimum of ___ test operators should be inside the pressurised area during any pressure test where an ________ ground test unit is used as the air supply source. when using _______ for the air supply a _____ operator to run the engines is required
TESTING OF PRESSURISATION SYSTEMS. TEST PREP
- all persons in the cabin must be MEDICALLY fit
- a minimum of TWO test operators should be inside the pressurised area during any pressure test where an EXTERNAL ground test unit is used as the air supply source. when using ENGINES for the air supply a THIRD operator to run the engines is required
TESTING OF PRESSURISATION SYSTEMS. FUNCTIONAL TESTS
cabin pressurisation tests can be carried out by:
- running the _______
- connecting a _______ supply unit
- using bleed air from the ___
TESTING OF PRESSURISATION SYSTEMS. FUNCTIONAL TESTS
cabin pressurisation tests can be carried out by:
- running the ENGINES
- connecting a GROUND supply unit
- using bleed air from the APU
TESTING OF PRESSURISATION SYSTEMS. LEAK RATE TEST
leak rate tests are necessary at specified periods to ensure that no marked __________ in the sealing standard of the aircraft fuselage has occurred
the tests should also be carried out whenever a COMPONENT affecting the pressurised area is renewed, refitted or modified, and also after _____ pressure test
TESTING OF PRESSURISATION SYSTEMS. LEAK RATE TEST
leak rate tests are necessary at specified periods to ensure that no marked DETERIORATION in the sealing standard of the aircraft fuselage has occurred
the tests should also be carried out whenever a COMPONENT affecting the pressurised area is renewed, refitted or modified, and also after PROOF pressure test
TESTING OF PRESSURISATION SYSTEMS. PROOF PRESSURE CHECK
this is carried out during __________
a proof pressure test is carried out at 1.__ times the maximum operating ___________ pressure
major ________ or alterations to structural design may require a proof test only if the ___ and manufacturer require it; smaller structural repairs are tested up to ______ valve pressure
note: when ground testing a pressure cabin, as the differential pressure __________ the cabin rate of change indicator will show a rate of ________. ensure all controls are reset from _______ test to the correct position required for _______
TESTING OF PRESSURISATION SYSTEMS. PROOF PRESSURE CHECK
this is carried out during MANUFACTURE
a proof pressure test is carried out at 1.33 times the maximum operating DIFFERENTIAL pressure
major REPAIRS or alterations to structural design may require a proof test only if the CAA and manufacturer require it; smaller structural repairs are tested up to SAFETY valve pressure
note: when ground testing a pressure cabin, as the differential pressure INCREASES the cabin rate of change indicator will show a rate of DESCENT. ensure all controls are reset from GROUND test to the correct position required for FLIGHT
