protection systems book 1 Flashcards
(49 cards)
during flight in certain conditions, ice may accumulate on all the forward facing areas of the aircraft. these accumulations have the following effects on an aircraft:
- a _________ in lift due to a change in aerofoil section and loss of ________ flow of air around leading edges and top surfaces
- an ________ in drag for the same reasons that cause a loss of lift. the rough surface increases skin friction
- _________ propeller efficiency because of the change in blade shape. there is the possibility of damage to the fuselage as a result of ice being thrown from he propellers
- there may be a loss of _______ due to ice restricting or preventing movement of _______ surfaces
- an _______ in weight causing loss of height. a change in the distribution of the weight can cause a change in the trim of the aircraft and possibly a loss of stability
- ________ of pitot static heads
- loss of ______ through the forward facing cabin windows or windshields
during flight in certain conditions, ice may accumulate on all the forward facing areas of the aircraft. these accumulations have the following effects on an aircraft:
- a DECREASE in lift due to a change in aerofoil section and loss of STREAMLINE flow of air around leading edges and top surfaces
- an INCREASE in drag for the same reasons that cause a loss of lift. the rough surface increases skin friction
- DECREASES propeller efficiency because of the change in blade shape. there is the possibility of damage to the fuselage as a result of ice being thrown from he propellers
- there may be a loss of CONTROL due to ice restricting or preventing movement of CONTROL surfaces
- an INCREASE in weight causing loss of height. a change in the distribution of the weight can cause a change in the trim of the aircraft and possibly a loss of stability
- BLOCKAGE of pitot static heads
- loss of VISION through the forward facing cabin windows or windshields
ice will only form on an aircraft when it is flying in cloud or precipitation where the water droplets are ___________
ice will only form on an aircraft when it is flying in cloud or precipitation where the water droplets are SUPERCOOLED
ice formation
an aerofoil with a relatively _____ radius leading edge, flying at slow or moderate airspeed creates a large pressure wave ahead of the leading edge. this forces the air around the aerofoil contour, carrying most of the moisture with it. some of the droplets are too heavy to make the tun and impact the leading edge. collection efficiencies are approximately __%
a _____ radius leading edge does not generate a large pressure wave and the ice collection efficiency can be as high as __%
on any aircraft the leading edge of the horizontal stabiliser has a _______ radius than that of the wing. the stabiliser therefore has a _______ collection efficiency than the wing. the stabiliser may accumulate a _____ amount of ice while there is little or no build up on the wing
ice formation
an aerofoil with a relatively LARGE radius leading edge, flying at slow or moderate airspeed creates a large pressure wave ahead of the leading edge. this forces the air around the aerofoil contour, carrying most of the moisture with it. some of the droplets are too heavy to make the tun and impact the leading edge. collection efficiencies are approximately 45%
a SMALL radius leading edge does not generate a large pressure wave and the ice collection efficiency can be as high as 95%
on any aircraft the leading edge of the horizontal stabiliser has a SMALLER radius than that of the wing. the stabiliser therefore has a HIGHER collection efficiency than the wing. the stabiliser may accumulate a LARGE amount of ice while there is little or no build up on the wing
glaze icing or runback icing (clear)
- MOST DANGEROUS as has much greater spoiling effect on airflow
- temp range from _- -__ celcius
- small portion of droplet freezes at stagnation point which releases _____ heat, delaying freezing of remainder of droplet which runs back over aerofoil and freezes
- droplets unite in liquid state and little or no ___ trapped between them
- transparent or translucent ice with ______ surface appearance
- accumulates _______ and can form beyond effective area of de-iced or anti-iced surfaces
glaze icing or runback icing (clear)
- MOST DANGEROUS as has much greater spoiling effect on airflow
- temp range from 2- -10 celcius
- small portion of droplet freezes at stagnation point which releases LATENT heat, delaying freezing of remainder of droplet which runs back over aerofoil and freezes
- droplets unite in liquid state and little or no AIR trapped between them
- transparent or translucent ice with GLOSSY surface appearance
- accumulates RAPIDLY and can form beyond effective area of de-iced or anti-iced surfaces
mixed ice (glime)
- when complete freezing of water droplets on impact takes longer than ____ ice
- _____ water particles, ___ pressure
- _______ appearance
- extends ______ back over leading edge and not as _____ as rime ice
mixed ice (glime)
- when complete freezing of water droplets on impact takes longer than RIME ice
- LARGE water particles, LOW pressure
- OPAQUE appearance
- extends FURTHER back over leading edge and not as ROUGH as rime ice
rime ice
- ________ freezing of water particles on impact
- _____ water particles, very ___ temperature
- air trapped causing _____ texture and white _________ appearance
rime ice
- COMPLETE freezing of water particles on impact
- SMALL water particles, very LOW temperature
- air trapped causing LIGHT texture and white CRYSTALINE appearance
dry icing
- icing does not occur above _____m (_____ feet)
- however if ice crystals are present in sufficient volume, they can accumulate in ________ cooling ducts and _____ air intakes causing blockage
dry icing
- icing does not occur above 12000m (40000 feet)
- however if ice crystals are present in sufficient volume, they can accumulate in AUXILLARY cooling ducts and ENGINE air intakes causing blockage
hoar frost
- surface below ________ point 0 celsius
- forms in clear air, water vapour being converted directly into ice crystals forming a _____ ________ coating
- sometimes occurs on surface of the wings where _______ fuel tanks are fitted
hoar frost
- surface below FREEZING point 0 celsius
- forms in clear air, water vapour being converted directly into ice crystals forming a WHITE FEATHERY coating
- sometimes occurs on surface of the wings where INTEGRAL fuel tanks are fitted
de-icing and anti-icing
there are two basic methods of solving icing problems in aircraft:
- __-icing
- ____-icing
de-icing and anti-icing
there are two basic methods of solving icing problems in aircraft:
- DE-icing
- ANTI-icing
aerofoil ice protection
there are four primary methods used for aerofoil ice protection
- _______ - by ducting hot air along the inner surface of the aerofoil leading edges
- __________ - by fitting heater elements to the aerofoil leading edges
- _________ - the fitting of compressed air operated overshoes to the aerofoil leading edges. these pulsate and remove ice after it has formed
- _____ - by pumping a fluid having a low freezing point, from distributors fitted to the aerofoil leading edges
aerofoil ice protection
there are four primary methods used for aerofoil ice protection
- THERMAL - by ducting hot air along the inner surface of the aerofoil leading edges
- ELECTRICAL - by fitting heater elements to the aerofoil leading edges
- PNEUMATIC - the fitting of compressed air operated overshoes to the aerofoil leading edges. these pulsate and remove ice after it has formed
- FLUID - by pumping a fluid having a low freezing point, from distributors fitted to the aerofoil leading edges
thermal systems general
thermal anti icing uses heated air flowing through passages in the leading edges of wings, stabilisers and engine cowlings to prevent formation of ice. in modern aircraft the heated air is obtained from the turbine engine _____ ___ system.
air is distributed using perforated air ducting called _______ or spray tubing
thermal systems general
thermal anti icing uses heated air flowing through passages in the leading edges of wings, stabilisers and engine cowlings to prevent formation of ice. in modern aircraft the heated air is obtained from the turbine engine BLEED AIR system.
air is distributed using perforated air ducting called PICCOLO or spray tubing
thermal ice protection systems
the wing shut off valve is sprung loaded ____. it remains open until the tail de-icing _____ is actuated
approximately . minutes later, the timer relay automatically releases and shuts off the current to both valves. this causes the wing shut off valve to ____ and the tail shut off valve to _____
thermal ice protection systems
the wing shut off valve is sprung loaded OPEN. it remains open until the tail de-icing RELAY is actuated
approximately 2.5 minutes later, the timer relay automatically releases and shuts off the current to both valves. this causes the wing shut off valve to OPEN and the tail shut off valve to CLOSE
thermal ice protection systems
overheat switches close the anti ice valves if the air temperature in the ducts exceeds __ degrees during ground testing. in ______, the overheat circuit is not used
thermal ice protection systems
overheat switches close the anti ice valves if the air temperature in the ducts exceeds 90 degrees during ground testing. in FLIGHT, the overheat circuit is not used
duct maintenance
adequate safety precautions must be taken when inspecting duct sections under ________
duct maintenance
adequate safety precautions must be taken when inspecting duct sections under PRESSURE
electrical ice protection systems. general.
spray mats, also known as heater mats are available for both anti icing and de icing. anti-icing mats are supplied _____________ with electricity whilst de-icing mats are ______________ heated.
electrical ice protection systems. general.
spray mats, also known as heater mats are available for both anti icing and de icing. anti-icing mats are supplied CONTINUOUSLY with electricity whilst de-icing mats are INTERMITTENTLY heated.
electrical ice protection systems. general.
on intermittently heated sections, ____________ heated breaker strips are fitted between the intermittently heated areas. this ensures that the small areas of ice removed are small enough not to cause a hazard to the aircraft.
the power supplies normally used are ___V to ___V variable frequency AC for heating, and ___V AC and __V DC for control
electrical ice protection systems. general.
on intermittently heated sections, CONTINUOUSLY heated breaker strips are fitted between the intermittently heated areas. this ensures that the small areas of ice removed are small enough not to cause a hazard to the aircraft.
the power supplies normally used are 115V to 200V variable frequency AC for heating, and 115V AC and 28V DC for control
construction of heater mats
a typical heater mat consists of a ________ heater element sandwiched between layers of _____ _____ reinforced plastic
the outer layer of glass fibre is _______ than the inner layer
to protect the heater mat from rain or hail erosion and impact damage from runway debris, the heater mat is covered by an _______ _________ coating
construction of heater mats
a typical heater mat consists of a METALLIC heater element sandwiched between layers of GLASS FIBRE reinforced plastic
the outer layer of glass fibre is THINNER than the inner layer
to protect the heater mat from rain or hail erosion and impact damage from runway debris, the heater mat is covered by an EROSION RESISTANT coating
control and indication
the controller monitors a __________ sensor and keeps the leading edge and breaker strips at a _____________ temperature to prevent ice forming
the controllers monitor the system for proper _______ use, ___________ sensor function and minimum and maximum ____________. the system will switch off if an over temp is detected. the controller will illuminate an ____________ on the flight deck to alert the crew if there is a failure of the system
control and indication
the controller monitors a TEMPERATURE sensor and keeps the leading edge and breaker strips at a PREDETERMINED temperature to prevent ice forming
the controllers monitor the system for proper CURRENT use, TEMPERATURE sensor function and minimum and maximum TEMPERATURES. the system will switch off if an over temp is detected. the controller will illuminate an ANNUNCIATOR on the flight deck to alert the crew if there is a failure of the system
typical pneumatic de-icing system
- ______ tube inflates, cracking the ice
- _____ tubes inflate, lifting cracked ice, causing it to be blown off
typical pneumatic de-icing system
- CENTRE tube inflates, cracking the ice
- OUTER tubes inflate, lifting cracked ice, causing it to be blown off
pneumatic de icing system air supply
whenever the system is switched off, or at the end of an inflation stage, the de-icer boots are deflated by ______. the vacuum can be obtained from a ______ pump
in most _______ _______ types, vacuum is usually obtained from the venturi section of an _______ nozzle or ___ pump
pneumatic de icing system air supply
whenever the system is switched off, or at the end of an inflation stage, the de-icer boots are deflated by VACUUM. the vacuum can be obtained from a VACUUM pump
in most TURBINE POWERED types, vacuum is usually obtained from the venturi section of an EJECTOR nozzle or JET pump
deicer boot damage
irreparable damage is generally:
- cuts and tears longer than _.__” (19mm)
- cuts and tears which cross stitch lines or are within _.___” (3.2mm) of a stitch line
- ______ stitches
de-icer boots with irreparable damage must be _______
deicer boot damage
irreparable damage is generally:
- cuts and tears longer than 0.75” (19mm)
- cuts and tears which cross stitch lines or are within 0.125” (3.2mm) of a stitch line
- broken stitches
de-icer boots with irreparable damage must be REPLACED
testing a pneumatic de-icing system
- carried out at check periods specified in the ________ maintenance schedules
- carried out when a system ___________ occurs, major __________ is replaced or ______ to de-icer boot
- method of test depends on ___
testing a pneumatic de-icing system
- carried out at check periods specified in the APPROVED maintenance schedules
- carried out when a system MALFUNCTION occurs, major COMPONENT is replaced or REPAIR to de-icer boot
- method of test depends on AMM
testing a pneumatic de-icing system
depends on AMM but in general:
- tested using engine _____ ___ or using ______ ____ trolley
- ________ and ______ indicators should be checked to ensure that supplies are maintained at the specified values
- with system on, boots should _______ and _______ in correct _________ and for correct ____. pressure gauge should _________ accordingly
- if inflation or deflation is ________, may be caused by _________ in system or sticking ________ valves
- with system off, boots should _______ completely and lie flat against the leading edge of aerofoil
testing a pneumatic de-icing system
depends on AMM but in general:
- tested using engine BLEED AIR or using GROUND TEST trolley
- PRESSURE and VACUUM indicators should be checked to ensure that supplies are maintained at the specified values
- with system on, boots should INFLATE and DEFLATE in correct SEQUENCE and for correct TIME. pressure gauge should FLUCTUATE accordingly
- if inflation or deflation is SLUGGISH, may be caused by OBSTRUCTION in system or sticking SOLENOID valves
- with system off, boots should DEFLATE completely and lie flat against the leading edge of aerofoil
fluid ice protection systems. anti icing system
in the anti-icing mode a ___________ film of fluid is pumped continuously from the panels and prevents the formation of ice. this requires the aircraft to carry a large quantity of _____ which is _____ and could reduce the _______
fluid ice protection systems. anti icing system
in the anti-icing mode a PROTECTIVE film of fluid is pumped continuously from the panels and prevents the formation of ice. this requires the aircraft to carry a large quantity of FLUID which is HEAVY and could reduce the PAYLOAD
