Maximum Brake Energy Limit A320/321
Thread Starter
Joined: Aug 2005
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From: Malaysia
Maximum Brake Energy Limit A320/321
Could any expert kindly point me to the reference where I can find the Maximum Brake Energy limit for A320/321?
I have searched through the thread here and someone pointed out that it's 150C on brake temperature and it's in the "Getting grips with ..." . I have looked through each & everyone of the "Getting grips with ..." documents but could not find it. Also, I believe it's not a straight forward figure of 150C as brake energy limit varies with pressure alt, OAT, runway slope, wind, TOW, etc.
It should come in a chart or a graph format.
Thanks.
I have searched through the thread here and someone pointed out that it's 150C on brake temperature and it's in the "Getting grips with ..." . I have looked through each & everyone of the "Getting grips with ..." documents but could not find it. Also, I believe it's not a straight forward figure of 150C as brake energy limit varies with pressure alt, OAT, runway slope, wind, TOW, etc.
It should come in a chart or a graph format.
Thanks.
Only half a speed-brake
Joined: Apr 2003
Posts: 4,459
Likes: 136
From: Commuting not home
While I do not have the graphs / data you ask for, maybe little clarification would help.
Kinetic energy is simply calculated E=1/2*mass*velocity^2. V is de facto GS so wind, T, p, play a role. In an RTO case all this energy is converted to heat that needs to be soaked by brakes without increasing their temperature above a limit. The cooler the brakes at the begining, the higher the energy reserve.
There is a 300 deg limit, tied to hyd fluid flash point.
If your AC is equipped with brake fans, they should be running as per manufacturer SOP if Temp indication is above 100 deg. Once fans are on, they channel cooler air over temp sensors, so the indication may not be in agreement with the actual brake temperature. Hence the guidance that with brake fans on the maximum indicated temperature is 150 deg, in order to observe the 300 limit of actual brake temperature.
FD (the un-real)
Kinetic energy is simply calculated E=1/2*mass*velocity^2. V is de facto GS so wind, T, p, play a role. In an RTO case all this energy is converted to heat that needs to be soaked by brakes without increasing their temperature above a limit. The cooler the brakes at the begining, the higher the energy reserve.
There is a 300 deg limit, tied to hyd fluid flash point.
If your AC is equipped with brake fans, they should be running as per manufacturer SOP if Temp indication is above 100 deg. Once fans are on, they channel cooler air over temp sensors, so the indication may not be in agreement with the actual brake temperature. Hence the guidance that with brake fans on the maximum indicated temperature is 150 deg, in order to observe the 300 limit of actual brake temperature.
FD (the un-real)
Joined: Jul 2008
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From: south pacific vagrant
I have the same query as Aikon. FCOM (in our company atleast) has scant information on it.
Really, the only place I've come across it is in company printed Take Off Performance charts where brake energy is given as the limiting factor for some RTOWs. Clearly then, the software takes it into account.
Really, the only place I've come across it is in company printed Take Off Performance charts where brake energy is given as the limiting factor for some RTOWs. Clearly then, the software takes it into account.
Joined: Dec 2006
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From: N33 24.7 E36 30.8 E 36 30.8
Hi Gentlemen
If You Could Tell Me The Aircraft Version / Engine Of Your Aircraft I Will Get Yoy The Vmbe Value
I Have A Book In Pdf Format..the Name Is A320 Family Instructor Support..issued By The Training And Flight Operations Support Division..and It Has The Vmbe Value For Several A320/321 Aircraft Versions With Both Cfm-56 And Iae V2500 Engines Among Other Things
Another Option Is To Provide Me With An E-mail And I Will Happily Send It To You All..the Size Is Approx. 8.96 Mb
Regards
Bf
If You Could Tell Me The Aircraft Version / Engine Of Your Aircraft I Will Get Yoy The Vmbe Value
I Have A Book In Pdf Format..the Name Is A320 Family Instructor Support..issued By The Training And Flight Operations Support Division..and It Has The Vmbe Value For Several A320/321 Aircraft Versions With Both Cfm-56 And Iae V2500 Engines Among Other Things
Another Option Is To Provide Me With An E-mail And I Will Happily Send It To You All..the Size Is Approx. 8.96 Mb
Regards
Bf
Joined: Jul 2002
Posts: 148
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From: Europe
At the risk of teaching granny...
Ensure that the brake (manufacturer, cooling fans, brake material and type) you seek is the one in the paperwork... More than one has been fitted during the life of these aircraft.
Ensure that the brake (manufacturer, cooling fans, brake material and type) you seek is the one in the paperwork... More than one has been fitted during the life of these aircraft.
Only half a speed-brake
Joined: Apr 2003
Posts: 4,459
Likes: 136
From: Commuting not home
To decipher FCOM info, it is necessary to destingush which limit is sought.
rotation speed ... tire limit GS 195 kt
hyd flash point ... 300 deg before takeoff with fans off
energy resrve ..... cool at beginning .... 300/150
...... max V1 to stop without burning brakes away .... weight dependent in MegaJoules according to brake installed; normally included in RTOW / PC perf software.
rotation speed ... tire limit GS 195 kt
hyd flash point ... 300 deg before takeoff with fans off
energy resrve ..... cool at beginning .... 300/150
...... max V1 to stop without burning brakes away .... weight dependent in MegaJoules according to brake installed; normally included in RTOW / PC perf software.
Thread Starter
Joined: Aug 2005
Posts: 37
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From: Malaysia
Thanks guys. Checked the brake cooling schedule info in MEL. Great info.
By the way, am I right to say that as long as the aborted TO is done within the V1 calculated by the TO performance chart (Octopus Chart), it is safe to say that the maximum brake energy limit will not be reached if your brake temp. is below 300C without brake fan & 150C with brake fan?
But if that is so, why is it that in FCOM 3 stated that the brake fan should be on when an green arc appears on the brake temp. indication (above 100C)?
By the way, am I right to say that as long as the aborted TO is done within the V1 calculated by the TO performance chart (Octopus Chart), it is safe to say that the maximum brake energy limit will not be reached if your brake temp. is below 300C without brake fan & 150C with brake fan?
But if that is so, why is it that in FCOM 3 stated that the brake fan should be on when an green arc appears on the brake temp. indication (above 100C)?
