Anti/de icing systems
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Anti/de icing systems
Hello,
I've got some troubles answering those following questions about anti/de icing.
May someone in here please help me?
Here are the questions :
1) Rain repellent :
a- prevents rain hitting the windscreen
b- increases the ability of the water to run off the windscreen
I would say b), the idea of rain droplets not getting in contact with the windscreen sounds a bit weird for me.
2) Prior to take-off in a twin jet aircarft the OAT is +8°C, there is standing water on the runway and the RVR is 900 metres :
a- the igniters must be on for the take off
b- the engine anti-icing must be on and precautionarry use oft he igniters may be required
c- the engine and airframe anti-icing must be on
d- the engine anti-icing and igniters must be off and precautionnary use of the airframe ani-icing may be required
I'd say a).
3) With respect to frost forming on the aircraft prior to flight :
a) all deposits of frost must be removed from the wings before flight
b) frost on the lower surface of the wing during take-off is acceptable
I'm hesitating on this question because it is mentionned in my atpl book that many large aircrafts are allowed to take off with small ammounts of frost over "fuel tank areas of wing undersurfaces".
4) A typical turbofan aircraft hot air anti-icing system uses compressor bleed air, when this type of system is activated it will cause :
a- a reduction of EPR, an increase in EGT and an increase in SFC.
b- a reduction of EGT, an increase in EPR and an increase in SFC
c) a reduction of SFC, an increase in EGT and an increase in EPR
d) a reduction of EPR, an increase in EGT and no effect on SFC
Thank you for your help guys!
I've got some troubles answering those following questions about anti/de icing.
May someone in here please help me?
Here are the questions :
1) Rain repellent :
a- prevents rain hitting the windscreen
b- increases the ability of the water to run off the windscreen
I would say b), the idea of rain droplets not getting in contact with the windscreen sounds a bit weird for me.
2) Prior to take-off in a twin jet aircarft the OAT is +8°C, there is standing water on the runway and the RVR is 900 metres :
a- the igniters must be on for the take off
b- the engine anti-icing must be on and precautionarry use oft he igniters may be required
c- the engine and airframe anti-icing must be on
d- the engine anti-icing and igniters must be off and precautionnary use of the airframe ani-icing may be required
I'd say a).
3) With respect to frost forming on the aircraft prior to flight :
a) all deposits of frost must be removed from the wings before flight
b) frost on the lower surface of the wing during take-off is acceptable
I'm hesitating on this question because it is mentionned in my atpl book that many large aircrafts are allowed to take off with small ammounts of frost over "fuel tank areas of wing undersurfaces".
4) A typical turbofan aircraft hot air anti-icing system uses compressor bleed air, when this type of system is activated it will cause :
a- a reduction of EPR, an increase in EGT and an increase in SFC.
b- a reduction of EGT, an increase in EPR and an increase in SFC
c) a reduction of SFC, an increase in EGT and an increase in EPR
d) a reduction of EPR, an increase in EGT and no effect on SFC
Thank you for your help guys!
I'll try!
1) b is correct. Although Rain Repellent does put a film between the windscreen and the rain, it does (drastically!) aid the water to run off.
2)a. I don't know of any aircraft that is allowed to take off with de/anti ice selected on, although no doubt someone will come along and prove me wrong.
3) Depends on the a/c and SOP's, but I think you can generally say b is correct. Out aircraft is permitted to take off with frost on the underside of the wing, on the fuselage and nacelles, providing it is thin enough so detail can be made out beneath it. I.e. if you can still read the warning stickers, see rivets etc, you can go. But not with frost on the top of the wing.
4)Not sure, but would go with a.
Good Luck!
1) b is correct. Although Rain Repellent does put a film between the windscreen and the rain, it does (drastically!) aid the water to run off.
2)a. I don't know of any aircraft that is allowed to take off with de/anti ice selected on, although no doubt someone will come along and prove me wrong.
3) Depends on the a/c and SOP's, but I think you can generally say b is correct. Out aircraft is permitted to take off with frost on the underside of the wing, on the fuselage and nacelles, providing it is thin enough so detail can be made out beneath it. I.e. if you can still read the warning stickers, see rivets etc, you can go. But not with frost on the top of the wing.
4)Not sure, but would go with a.
Good Luck!
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Regarding 2;
In most jet aircraft (having operated Boeing and Airbus), the definition for the need for ENGINE anti-ice is +10oC or less, visible moisture or vis less than 1500m. It's also common practise to switch on the ignitors for take-off and whenever ENGINE anti-ice is selected because of the reduced flow/increased risk of flame-out.
In my experience, AIRFRAME anti-ice is a no-no whenever on the ground unless you wish to melt the wings. (I'm sure it says in the MEL that melted wings are a no go item.)
So I think the closest is B
Regarding 4;
SFC is will increase (i.e. get worse)
EGT will increase as their is less flow through the combustion chamber
EPR will decrease because airflow is lost via the bleed system.
Regarding 3;
The previous poster is correct, 'small' amounts of frost in the vicinity of the fuel tanks are allowed BUT the question doesn't say that so I'd be cautious and say A.
In most jet aircraft (having operated Boeing and Airbus), the definition for the need for ENGINE anti-ice is +10oC or less, visible moisture or vis less than 1500m. It's also common practise to switch on the ignitors for take-off and whenever ENGINE anti-ice is selected because of the reduced flow/increased risk of flame-out.
In my experience, AIRFRAME anti-ice is a no-no whenever on the ground unless you wish to melt the wings. (I'm sure it says in the MEL that melted wings are a no go item.)
So I think the closest is B
Regarding 4;
SFC is will increase (i.e. get worse)
EGT will increase as their is less flow through the combustion chamber
EPR will decrease because airflow is lost via the bleed system.
Regarding 3;
The previous poster is correct, 'small' amounts of frost in the vicinity of the fuel tanks are allowed BUT the question doesn't say that so I'd be cautious and say A.
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Regarding 3;
The previous poster is correct, 'small' amounts of frost in the vicinity of the fuel tanks are allowed BUT the question doesn't say that so I'd be cautious and say A.
The previous poster is correct, 'small' amounts of frost in the vicinity of the fuel tanks are allowed BUT the question doesn't say that so I'd be cautious and say A.
In the question regarding frost on wings, answer A says "all deposits of frost must be removed from the wings before flight", so i assume that it means that even small ammounts must be removed and are not acceptable in any way.
Now, it is said in my book that many aircraft maintenance book allow thin layers of frost to build up over the lower part of the wings, but it's not necessarily approved by the CAA or any other administration : it depends on the manufatcurer.
That's why i definitely don't know what's the right answer.
What do you think about this?
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1. B
2. It depends on the manufacturer. Fokker 70/100 says that this isn't icing conditions, Embraer 190 says it is and Engine only required. In both cases, iginition is recommended to be left in "Auto" rather than "On", so tell the examiner to KFO. I'm sure every other manufacturer will have a different answer.
3. B - Three millimeters of ice allowed under the wings on the above types.
4. A - You don't get owt for nowt!
PM
2. It depends on the manufacturer. Fokker 70/100 says that this isn't icing conditions, Embraer 190 says it is and Engine only required. In both cases, iginition is recommended to be left in "Auto" rather than "On", so tell the examiner to KFO. I'm sure every other manufacturer will have a different answer.
3. B - Three millimeters of ice allowed under the wings on the above types.
4. A - You don't get owt for nowt!
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Re: Q2.
Most jet aircraft will require ignition ON for take-off, regardless of flight conditions (e.g B737) as this provides a measure of flame-out protection. If there is standing water it will always (in my experience of jet ops) be ON.
Engine Anti Ice will be required below a certain OAT if moisture is present - again, for B737 I think this figure is usually +10C (certainly on the -200) although as stated by other posters this may vary by type. Given that the B737 seems to be the "aeroplane of choice" for the JAA, I would say ON with +8C and that RVR/standing water.
Airframe Anti/De-Ice must be treated as a separate issue from Engine Anti-Ice. Bleed air type airframe anti-ice systems are usually used to DE-ICE and so are not used unless ice has already built up on the airframe.
Prior to take-off, airframe de-icing will be carried out using chemical de-icer and the crew will plan to be airborne before the end of the holdover time (which varies according to met conditions and type of fluid used). If such chemical de-ice is not availanble, the aeroplanes airframe de-icing system may (depending upon type) be used but the effect on performance will have to be calculated. For example, using airframe de-ice on a B737-200 will typically reduce MTOW by about 3,500kg!
Hope that helps.
Most jet aircraft will require ignition ON for take-off, regardless of flight conditions (e.g B737) as this provides a measure of flame-out protection. If there is standing water it will always (in my experience of jet ops) be ON.
Engine Anti Ice will be required below a certain OAT if moisture is present - again, for B737 I think this figure is usually +10C (certainly on the -200) although as stated by other posters this may vary by type. Given that the B737 seems to be the "aeroplane of choice" for the JAA, I would say ON with +8C and that RVR/standing water.
Airframe Anti/De-Ice must be treated as a separate issue from Engine Anti-Ice. Bleed air type airframe anti-ice systems are usually used to DE-ICE and so are not used unless ice has already built up on the airframe.
Prior to take-off, airframe de-icing will be carried out using chemical de-icer and the crew will plan to be airborne before the end of the holdover time (which varies according to met conditions and type of fluid used). If such chemical de-ice is not availanble, the aeroplanes airframe de-icing system may (depending upon type) be used but the effect on performance will have to be calculated. For example, using airframe de-ice on a B737-200 will typically reduce MTOW by about 3,500kg!
Hope that helps.
