A320 RAT
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A320 RAT
Hey,
is there a difference when I deploy the RAT manually from the EMER ELEC PWR panel or the hydraulic panel?
My captain told me that tgere is a difference but i didnt found an information in the FCOM.
Best regards
is there a difference when I deploy the RAT manually from the EMER ELEC PWR panel or the hydraulic panel?
My captain told me that tgere is a difference but i didnt found an information in the FCOM.
Best regards
Last edited by scheini111; 1st Sep 2014 at 20:59.
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A320 RAT
Hi, The difference is that from the HYD OVERHEAD PANEL you can deploy the RAT at any time and if you want to do it from the EMER ELEC PWR PANEL some condition must be met
-AC BUS 1 is not electrically supplied
-AC BIS 2 is not electrically supplied
-Aircraft speed is grater than 100kt
I hope this help
-AC BUS 1 is not electrically supplied
-AC BIS 2 is not electrically supplied
-Aircraft speed is grater than 100kt
I hope this help
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Thank you for your response!!!!
Last time I had electricity as topic and the Captain said when I deploy the RAT via the hydraulic panel, the RAT only generates hydraulic pressure and when the RAT will be deployed by the EMER ELEC PWR panel the RAT only generates electricity, but I did not found if it is true or not. In the FCOM is under controls and indicator (hydraulic) written refer to controls and indicator (electricity) and in my mind there is no difference. If I understand correctly, the RAT generates hydraulic pressure and this pressure drives the blue system and the emergency generator in all cases.
Best regards
Last time I had electricity as topic and the Captain said when I deploy the RAT via the hydraulic panel, the RAT only generates hydraulic pressure and when the RAT will be deployed by the EMER ELEC PWR panel the RAT only generates electricity, but I did not found if it is true or not. In the FCOM is under controls and indicator (hydraulic) written refer to controls and indicator (electricity) and in my mind there is no difference. If I understand correctly, the RAT generates hydraulic pressure and this pressure drives the blue system and the emergency generator in all cases.
Best regards
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If RAT is deployed manually from EMER ELEC PWR panel then it will pressurize the Blue Hyd system. Blue system will then power a hydraulic motor which runs the Emergency generator. There is a valve which opens and lets blue hydraulic to power the motor (Supply hydraulic power to CSM/G) if RAT is selected from EMER ELEC PWR panel. Also GCU will close the emergency generator line contactor if RAT is selected from EMER ELEC PWR panel (There is also AUTO logic for this). Selecting RAT Man ON on HYD panel will only deploy the RAT and pressurize the blue hyd system. It will not open the valve for the motor nor will the GCU close the line contactor. Hence on the HYD panel it says RAT MAN ON whereas on EMER ELEC PWR panel it says RAT & EMER GEN MAN ON (Auto).
Ref : FCOM DSC-24-10-30-30 EMER GEN Running.
Ref : FCOM DSC-24-10-30-30 EMER GEN Running.
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Hello scheini111,
I assume there is no fault with aircraft (ie AC 1+2 are powered and B HYD is powered as well) prior to pressing any RAT sw:
1. If U press the RAT sw on the HYD panel: nothing will happen other than the extension of the RAT. In this case the RAT will not power the B sys because it is already powered.
2. If U press the RAT sw on the ELEC panel: Again the RAT will extend but it will do nothing. However, the EMER GEN will be powered and coupled to the network (powered by the already running B sys). Auto decoupling of EMER GEN occurs at L/G extension or during landing roll at low speed (depends on how old is the aircraft)
Thanks
I assume there is no fault with aircraft (ie AC 1+2 are powered and B HYD is powered as well) prior to pressing any RAT sw:
1. If U press the RAT sw on the HYD panel: nothing will happen other than the extension of the RAT. In this case the RAT will not power the B sys because it is already powered.
2. If U press the RAT sw on the ELEC panel: Again the RAT will extend but it will do nothing. However, the EMER GEN will be powered and coupled to the network (powered by the already running B sys). Auto decoupling of EMER GEN occurs at L/G extension or during landing roll at low speed (depends on how old is the aircraft)
Thanks
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A320 RAT deployment: What, When, Why
I hope that some A320 series drivers have read this original post, noted the responses and gone back to their books and then their tech ops folks. That some active drivers do not understand the sequence and What-ifs of the RAT system - and exactly what it will - and will not do, troubles me. As I read the details, dropping the RAT in a crunch is a great move; but if one does not take the secondary steps to direct the RAT's energy to the proper systems, hydraulic and/or electrical, the the device is essentially worthless.. That a couple of very honest folks do NOT know how to apply the RAT's energy capture to their systems is, at the least, commendable - and troublesome. Especially on the Bus, where nearly everything can be assigned to high-level automation, can they fly a limited airplane with only basic functions? Not INSTANTLY knowing how to apply the RAT's energy to needed services troubles me. Who direct's a faulted airplane's functions? Is it the crew, the faulty system, or nothing? That such event are exceedingly rare is just not quite good enough. Who is driving?
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If I recall correctly from my engineer's course, pressing either button simply activates a (different) solenoid to drop the RAT. Each release solenoid is supplied from a different hot bus. The reason there are two buttons is to make it simpler for you folks in an emergency; loss of electrics, press the ELEC button, loss of hydraulics, press the HYD button. Both buttons will give you the same thing though.
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As an additional, I have come across issues in the past where the FCOM does not reflect the reality of the aircraft. The FCOM is written to help you folks deal with an emergency, it doesn't necessarily reflect how the aircraft systems work or are actually laid out.
The FCOM at first glance looks to be a handy little guide for us line engineers, but I know from experience that we engineers can't trust them to give us the whole story
The FCOM at first glance looks to be a handy little guide for us line engineers, but I know from experience that we engineers can't trust them to give us the whole story
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No, no both buttons do not give the same thing. RAT MAN ON on the HYD section of the the overhead panel will deploy the RAT and give you BLUE hydraulic pressure only. It will NOT connect the EMER GEN when pushed. If you had a G and B HYD system failure (not loss of fluid) you may use the MAN ON switch to make it just a G HYD failure.
RAT MAN ON on the EMER ELEC CONTROL PANEL will deploy the RAT, pressurising the BLUE hydraulic system AND connect the EMER GEN. It was a question in type rating.
The initial responder's answer was not terribly clear or correct either. The RAT auto extends if both AC 1 and 2 are unpowered and the speed is above 100 kts. It's not a requirement in order for you to push the button - the switches are always powered - push them and the RAT will deploy.
RAT MAN ON on the EMER ELEC CONTROL PANEL will deploy the RAT, pressurising the BLUE hydraulic system AND connect the EMER GEN. It was a question in type rating.
The initial responder's answer was not terribly clear or correct either. The RAT auto extends if both AC 1 and 2 are unpowered and the speed is above 100 kts. It's not a requirement in order for you to push the button - the switches are always powered - push them and the RAT will deploy.
Last edited by WhyByFlier; 4th Sep 2014 at 09:24.
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Well, I've just had a look at the wiring manual; both buttons just operate the DEPLOY solenoids.
BUT, like I say, the reality of the aircraft doesn't always reflect the FCOM. I'd imagine there's a good reason you get taught to follow the FCOM and not the AMM
BUT, like I say, the reality of the aircraft doesn't always reflect the FCOM. I'd imagine there's a good reason you get taught to follow the FCOM and not the AMM
Last edited by itsresidualmate; 4th Sep 2014 at 08:09.
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After a bit of digging in the wiring manual; looks like pressing the HYD button unlocks one solenoid and pops the RAT out giving Blue HYDS.
Pressing the ELEC button operates the second solenoid also popping the RAT out, but this switch also sends an input into the Constant Speed Gen.
So either switch will pop the RAT out, but only the ELEC will force the RAT Gen to power its respective systems. It looks like this is the reason for two switches; the RAT Gen takes priority over the systems it feeds.
So, having a HYD failure, pressing the HYD button will get the RAT out without force powering the RAT AC Gen. If you had a HYD failure and still had serviceable engine generators, but pressed the ELEC switch, you'd pop the RAT, still get hydraulics but you'd also force off the good engine generators (only on those bus bars the CSM/G supplies of course).
With HYDS taking priority over ELECS, the system logic would auto shut down the CSM/G if Blue HYDS reached a low pressure.
Clear as mud?!
Pressing the ELEC button operates the second solenoid also popping the RAT out, but this switch also sends an input into the Constant Speed Gen.
So either switch will pop the RAT out, but only the ELEC will force the RAT Gen to power its respective systems. It looks like this is the reason for two switches; the RAT Gen takes priority over the systems it feeds.
So, having a HYD failure, pressing the HYD button will get the RAT out without force powering the RAT AC Gen. If you had a HYD failure and still had serviceable engine generators, but pressed the ELEC switch, you'd pop the RAT, still get hydraulics but you'd also force off the good engine generators (only on those bus bars the CSM/G supplies of course).
With HYDS taking priority over ELECS, the system logic would auto shut down the CSM/G if Blue HYDS reached a low pressure.
Clear as mud?!
Last edited by itsresidualmate; 4th Sep 2014 at 08:53.
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Sure!
I would certainly not call it a "complaint!!"
Some drivers simply do not know/understand enough detail about their systems to use them effectively if/when some component breaks. Virtually all drivers do just fine with routine operations or limited MELs. When stuff breaks, and without a detailed understanding of systems and their interactions, sometimes that QRH is just not enough. Different folks understand their airplanes at different levels. It was not meant as a complaint and I do not think most read it that way. Just sayin'... the top of the pack thoroughly understands the system's interactions - and well before a given button gets pushed. Regards,
Some drivers simply do not know/understand enough detail about their systems to use them effectively if/when some component breaks. Virtually all drivers do just fine with routine operations or limited MELs. When stuff breaks, and without a detailed understanding of systems and their interactions, sometimes that QRH is just not enough. Different folks understand their airplanes at different levels. It was not meant as a complaint and I do not think most read it that way. Just sayin'... the top of the pack thoroughly understands the system's interactions - and well before a given button gets pushed. Regards,
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vilas,
my answer came in response to scheini111 query which, as I interpreted it, was about what happens if any RAT SWs is pressed and I assumed he meant that the A/C has no fault prior to pressing the SWs.
1. If the RAT EMER GEN SW is pressed, RAT will drop and EMER GEN will activate and powers AC ESS until L/G is down then EMER GEN will deactivate.
2. If the HYD RAT SW is pressed, the RAT will extend and it will do nothing except rotating. It will not power the B HYD SYS because B sys is already powered by its own electrical pump. in this case, just assume the B ELEC pump PB is selected OFF then RAT will immediately power the B SYS.
Thanks
my answer came in response to scheini111 query which, as I interpreted it, was about what happens if any RAT SWs is pressed and I assumed he meant that the A/C has no fault prior to pressing the SWs.
1. If the RAT EMER GEN SW is pressed, RAT will drop and EMER GEN will activate and powers AC ESS until L/G is down then EMER GEN will deactivate.
2. If the HYD RAT SW is pressed, the RAT will extend and it will do nothing except rotating. It will not power the B HYD SYS because B sys is already powered by its own electrical pump. in this case, just assume the B ELEC pump PB is selected OFF then RAT will immediately power the B SYS.
Thanks