Airbus Dual Eng Fail procedure question
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Yurich
Dual Eng Fail with APU available if the windmill is insufficient for hydraulics ECAM will ask for PTU OFF and Y electric pump on. You can recover flaps to land in CONF3. Each start attempt I think reduces battery life by 3mts.
Dual Eng Fail with APU available if the windmill is insufficient for hydraulics ECAM will ask for PTU OFF and Y electric pump on. You can recover flaps to land in CONF3. Each start attempt I think reduces battery life by 3mts.
Last edited by vilas; 17th Oct 2013 at 11:59.
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vilas
You are right! In case of
HYD Y ENG 2 PUMP LO PR (PTU INOPERATIVE)
YELLOW ENG 2 PUMP........................................................ ...................OFF
ASSOCIATED PROCEDURES
Y SYS LO PR
Note: If yellow system is affected, the yellow electrical pump may be used.
So, if we lost Y HYD SYS and fluids are available we can turn on Y ELEC PUMP but PTU should be OFF (INOP).
You are right! In case of
HYD Y ENG 2 PUMP LO PR (PTU INOPERATIVE)
YELLOW ENG 2 PUMP........................................................ ...................OFF
ASSOCIATED PROCEDURES
Y SYS LO PR
Note: If yellow system is affected, the yellow electrical pump may be used.
So, if we lost Y HYD SYS and fluids are available we can turn on Y ELEC PUMP but PTU should be OFF (INOP).
Seems to make a lot of sense to delay APU start attempt until below FL250. That's about 10 - 15 mins before landing, depending on terrain? So, with the Blue RAT Pump and the Yellow AC pump, you can get the slats and flaps out without depending on engines windmilling.
With no PTU, Green SYS press will depend on No 1 ED Pump windmilling. If no runway available, and landing rather than ditching, is extension of L/G recommended? Or is it simply pilot's discretion? Might need to be free-fallen...
Bon courage!
With no PTU, Green SYS press will depend on No 1 ED Pump windmilling. If no runway available, and landing rather than ditching, is extension of L/G recommended? Or is it simply pilot's discretion? Might need to be free-fallen...
Bon courage!
Last edited by Jetdriver; 17th Oct 2013 at 19:33.
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Chris Scot
On ELEC EMER Config APU start is limited to FL 250 and bleed below 200. It is not an option. Also landing gear is to be selected before 3000feet. It is also not an option. Gear can withstand hard impact. Landing on fuselage is likely to break it up
On ELEC EMER Config APU start is limited to FL 250 and bleed below 200. It is not an option. Also landing gear is to be selected before 3000feet. It is also not an option. Gear can withstand hard impact. Landing on fuselage is likely to break it up
Last edited by vilas; 18th Oct 2013 at 08:32.
Quote:
On ELEC EMER Config APU start is limited to FL 250 and bleed below 200. It is not an option. Also landing gear is to be selected before 3000feet. It is also not an option. Gear can withstand hard impact. Landing on fuselage is likely to break it up
WILCO vilas!
On ELEC EMER Config APU start is limited to FL 250 and bleed below 200. It is not an option. Also landing gear is to be selected before 3000feet. It is also not an option. Gear can withstand hard impact. Landing on fuselage is likely to break it up
WILCO vilas!
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Villas
If I was attempting a landing with dual engine failure and I was a bit lower than ideal around 3,000 ft - I would probably delay lowering the very draggy gear until I was certain I could make the runway.
However, if you must do it by the numbers - then fill your boots.
Also landing gear is to be selected before 3000feet. It is also not an option.
However, if you must do it by the numbers - then fill your boots.
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RRR
No option was between gear down and belly landing. If undershootin can be fatal you lower it later but lower it. Even collapsing gear is better than belly landing.
No option was between gear down and belly landing. If undershootin can be fatal you lower it later but lower it. Even collapsing gear is better than belly landing.
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@ fruitloop
[quoteI think that the reasoning of "ONLY" 1 start attempt is to maintain the 30 minutes duration of the Batteries ...][/quote]
I believe you are right . . .
I am looking at why [ if that is indeed the case] the RAT cannot give enough juice in the Hyd genny to power APU start attempts
- am trying to balance this off against "a successful APU start from the batt is unlikely" . . back to the books, I guess. . .
I believe you are right . . .
I am looking at why [ if that is indeed the case] the RAT cannot give enough juice in the Hyd genny to power APU start attempts
- am trying to balance this off against "a successful APU start from the batt is unlikely" . . back to the books, I guess. . .
Quote from Natstrackalpha:
I am looking at why [ if that is indeed the case] the RAT cannot give enough juice in the Hyd genny to power APU start attempts
- am trying to balance this off against "a successful APU start from the batt is unlikely" . . back to the books, I guess. . .
No manuals or QRH to hand, but if and when you have a chance try selecting the ELEC page on ECAM during a routine APU start on AC EXT PWR. Naturally, the 28V DC has to be produced by the TRs. (I emphasise the plural because, in the early days, TR1 had to do it alone.)
You'll see that both TR1 and TR2 quickly achieve 300 amps, which is top-of-scale on the read-out. Additionally, the two BATS register considerable current draws. That situation lasts for some seconds until the generator effect kicks in as the APU starter motor (and the APU itself) accelerate.
Having said that, the BATs always achieved reliable APU starts at sea-level in my experience, even on a cold morning.
I am looking at why [ if that is indeed the case] the RAT cannot give enough juice in the Hyd genny to power APU start attempts
- am trying to balance this off against "a successful APU start from the batt is unlikely" . . back to the books, I guess. . .
No manuals or QRH to hand, but if and when you have a chance try selecting the ELEC page on ECAM during a routine APU start on AC EXT PWR. Naturally, the 28V DC has to be produced by the TRs. (I emphasise the plural because, in the early days, TR1 had to do it alone.)
You'll see that both TR1 and TR2 quickly achieve 300 amps, which is top-of-scale on the read-out. Additionally, the two BATS register considerable current draws. That situation lasts for some seconds until the generator effect kicks in as the APU starter motor (and the APU itself) accelerate.
Having said that, the BATs always achieved reliable APU starts at sea-level in my experience, even on a cold morning.
Last edited by Chris Scott; 21st Oct 2013 at 17:07.
I see that vilas has done a much better job of addressing Natstrackalpha's question than I did!
What I meant to go on to say was that, if you use the ECAM ELEC page to estimate the peak 28VDC load demanded by the APU starter motor during a routine sea-level start, it may be in excess of 800A (a bit like the engine starter motor of a very large family car, but at a higher voltage). I would suggest that the AC power involved to produce that would be beyond the capability of the RAT emergency generator - hence the Emergency TR is not given that task.
In any case, that noisey little RAT has the far more important task of pressurising the Blue hydraulic system, which sustains the primary flying controls in the double-engine failure case. (Any Green and/or Yellow hydraulic pressure from windmilling engines is simply an unreliable bonus.)
What I meant to go on to say was that, if you use the ECAM ELEC page to estimate the peak 28VDC load demanded by the APU starter motor during a routine sea-level start, it may be in excess of 800A (a bit like the engine starter motor of a very large family car, but at a higher voltage). I would suggest that the AC power involved to produce that would be beyond the capability of the RAT emergency generator - hence the Emergency TR is not given that task.
In any case, that noisey little RAT has the far more important task of pressurising the Blue hydraulic system, which sustains the primary flying controls in the double-engine failure case. (Any Green and/or Yellow hydraulic pressure from windmilling engines is simply an unreliable bonus.)
Last edited by Chris Scott; 21st Oct 2013 at 19:53. Reason: Minor improvements...
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The A320 APU ALWAYS starts from battery power, even with fully powered electrical system.
Guys! That was really good, thank you everyone.
I would probably delay lowering the very draggy gear until I was certain I could make the runway.
wind - it drops?
I love the dual eng fail ex`s
- especially the loss of 2500` in a 180 turn!
And, don`t forget girls and biys - 280kts!
(gives PFL a whole new meaning!)
Isn't everyone going to die anyway?
circumstances, coupled with the age old notion of "ALWAYS LAND THE AIRCRAFT!" and NOBODY ON MY FLIGHT IS GOING TO GET HURT LEAST OF ALL THE PAX, NO!. Just for a piddly loss of both engines? You `re gonna be far, far too busy to die 
baby!
Last edited by Natstrackalpha; 28th Oct 2013 at 12:14.
APU Start
Quote from TyroPicard:
The A320 APU ALWAYS starts from battery power, even with fully powered electrical system.
I think it depends on what is meant by "battery power". But, putting that point to one side, as a statement it's a little unhelpful in that it could be inferred as meaning that the BATs will incur the same discharge whether or not normal AC power is available. Such an inference would be incorrect, as illustrated in my earlier post. That post can also be misinterpreted, however, so I'll try to clarify what I was describing.
As soon as APU start is initiated, and its starter motor starts drawing current (initially in excess of 800A), the resulting drop of voltage of the BATs is detected. TR1 and TR2 quickly provide over 300A each (exceeding top-of-scale on the ECAM ammeter displays). The combination of current from the two TRs results in the BATs only having to discharge at a (net) rate of about 100A each. That quickly falls as the APU accelerates, reducing the load from the starter motor.
When the rough figures here and in my first post are combined, they provide an indication of the sort of loads that BAT1 and BAT2 have to share if they are starting the APU unassisted on the ramp (in which case ECAM ELEC page will not be available). That is how my estimate of "initially in excess of 800A" is derived.
Airborne, in the case of dual engine-failure (or whatever reason both engine gennies are lost **), and consequential loss of TR1 and TR2, any APU start will equally depend entirely on the batteries. If the RAT is deployed and serviceable, the emergency generator should be powering the ESS TR. However, AFAIK (in the absence of a current FCOM or QRH) the ESS TR can only supply the DC ESS bus (and hence DC ESS SHED). Unlike TR1 and TR2, it cannot supply current for battery charging.
vilas, as one current on type, can you comment on any or all of the above?
** N.B.
Loss of both engine gennies with one or both engines running represents a completely different scenario from the dual engine-fail case, because the maximisation of battery life becomes a top priority.
The A320 APU ALWAYS starts from battery power, even with fully powered electrical system.
I think it depends on what is meant by "battery power". But, putting that point to one side, as a statement it's a little unhelpful in that it could be inferred as meaning that the BATs will incur the same discharge whether or not normal AC power is available. Such an inference would be incorrect, as illustrated in my earlier post. That post can also be misinterpreted, however, so I'll try to clarify what I was describing.
As soon as APU start is initiated, and its starter motor starts drawing current (initially in excess of 800A), the resulting drop of voltage of the BATs is detected. TR1 and TR2 quickly provide over 300A each (exceeding top-of-scale on the ECAM ammeter displays). The combination of current from the two TRs results in the BATs only having to discharge at a (net) rate of about 100A each. That quickly falls as the APU accelerates, reducing the load from the starter motor.
When the rough figures here and in my first post are combined, they provide an indication of the sort of loads that BAT1 and BAT2 have to share if they are starting the APU unassisted on the ramp (in which case ECAM ELEC page will not be available). That is how my estimate of "initially in excess of 800A" is derived.
Airborne, in the case of dual engine-failure (or whatever reason both engine gennies are lost **), and consequential loss of TR1 and TR2, any APU start will equally depend entirely on the batteries. If the RAT is deployed and serviceable, the emergency generator should be powering the ESS TR. However, AFAIK (in the absence of a current FCOM or QRH) the ESS TR can only supply the DC ESS bus (and hence DC ESS SHED). Unlike TR1 and TR2, it cannot supply current for battery charging.
vilas, as one current on type, can you comment on any or all of the above?
** N.B.
Loss of both engine gennies with one or both engines running represents a completely different scenario from the dual engine-fail case, because the maximisation of battery life becomes a top priority.
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the ESS TR can only supply the DC ESS bus (and hence DC ESS SHED)
ELEC page when EMER GEN running
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Chris Scott
All I can say about the Electrical system is
1. Batteries normally remain disconnected from DC BAT bus.
2. They get connected to DC BAT bus when they need charging.
3. They are also connected when APU master is ON. This is restricted to 3 mts. when in Emergency generator is running.
4. APU starting requires Batteries ON, merely power on DC BAT Bus is not enough. When ground power is supplying the power, DC BAT bus is supplied through DC bus1 but if batteries are OFF APU does not start.
6. In EMER ELEC only Essential buses DC and AC are powered. So batteries do not get charged. They get charged only through DC BAT Bus.
Loss of generators is not a problem because APU GEN can power the AC buses. But without APU it will remain in EMER ELEC.
All I can say about the Electrical system is
1. Batteries normally remain disconnected from DC BAT bus.
2. They get connected to DC BAT bus when they need charging.
3. They are also connected when APU master is ON. This is restricted to 3 mts. when in Emergency generator is running.
4. APU starting requires Batteries ON, merely power on DC BAT Bus is not enough. When ground power is supplying the power, DC BAT bus is supplied through DC bus1 but if batteries are OFF APU does not start.
6. In EMER ELEC only Essential buses DC and AC are powered. So batteries do not get charged. They get charged only through DC BAT Bus.
Loss of generators is not a problem because APU GEN can power the AC buses. But without APU it will remain in EMER ELEC.
Last edited by vilas; 29th Oct 2013 at 14:02.