Single engine taxi, yellow electric pump

[applecrumble]

Hey guys,

My operator recently changed its procedure on recommendation from Airbus. We now have to wait until we are in a straight line to operate the yellow electric pump. Anyone know as to why?
Cheers

[Amadis of Gaul]

You may be misreading the procedure. Ours says there have to be four conditions met before shutting down engine #2 after landing. These 4 being:

1. After landing check complete;
2. Cooldown period complied with (if necessary);
3. APU AVAIL light is on (because our birds don't have that much-discussed mod);
4. Aircraft moving in a straight line.

Once all those are met, THEN you go into the Engine 2 shutdown flow, which is Y pump on, engine A/I off, master off.

The reason we were given for #4 is that during power transfer it is possible for the BSCU to momentarily lose power, thus rendering you brakeless (again, momentarily) which would be a bad thing in a turn. Whether that's a legitimate concern I know not.

[FlightDetent]

Same as Amadis, except that the problem with electrical transient is a momentary discontinuity of NWS control. It is not in the FCOM, so my memory may be wrong.

[Escape Path]

Add "not braking" to those conditions. The wording in our FCOM says a "slight jerk may be felt if pressing the brake pedals while shutting down eng 2". Nothing slight about it! After being used to operating A320s with the enhanced hydraulic system, one day I had one with the old system, requested to shut down eng 2 while braking slightly in a straight line and it was quite a jolt! On the next flight back to base on that same day we happened to be taxiing to the same parking position on the same route as the "slight jerk" incident and there were tire skid marks where it had happened. Feet off the brakes ever since that!

Agree with Amadis and FD; be taxiing in a straight line before shutting down the engine, not to turn on the Y pump (me thinks something related to BSCU power supply/hydraulic pressure management during electrical transient while shutting #2?)

[Speedwinner]

Question: you arrive at the gate single engine taxi in. When to switch off the elec pump? After Peking brake set or when the engines are shut down? How’s about the ptu?

[AerocatS2A]

Originally Posted by Speedwinner

Question: you arrive at the gate single engine taxi in. When to switch off the elec pump? After Peking brake set or when the engines are shut down? How’s about the ptu?

Immediately prior to shutting down engine 1.

FCOM PRO-NOR-SUP-ENG-09 One Engine Taxi - At Arrival

[Bumblebee]

Originally Posted by AerocatS2A

Immediately prior to shutting down engine 1.

FCOM PRO-NOR-SUP-ENG-09 One Engine Taxi - At Arrival

Bearing in mind that switching off the Y Elec Pump is part of the PM flow - and shutting down ENG 1 is absolutely not dependent on it being done first. After all...ask yourself what happens when the Hold doors are opened..? (Answer: Y Elec Pump activates!)

Strong argument that the engine is shut down without delay once the Parking Brake set and Accumulator Pressure gauge and ECAM checked by PF.

[AerocatS2A]

Originally Posted by Bumblebee

Bearing in mind that switching off the Y Elec Pump is part of the PM flow - and shutting down ENG 1 is absolutely not dependent on it being done first. After all...ask yourself what happens when the Hold doors are opened..? (Answer: Y Elec Pump activates!)

Strong argument that the engine is shut down without delay once the Parking Brake set and Accumulator Pressure gauge and ECAM checked by PF.

Yes quite correct. The QRH is a better reference for the normal order of actions.

[Black Pudding]

Originally Posted by Amadis of Gaul

You may be misreading the procedure. Ours says there have to be four conditions met before shutting down engine #2 after landing. These 4 being:

1. After landing check complete;
2. Cooldown period complied with (if necessary);
3. APU AVAIL light is on (because our birds don't have that much-discussed mod);
4. Aircraft moving in a straight line.

Once all those are met, THEN you go into the Engine 2 shutdown flow, which is Y pump on, engine A/I off, master off.

The reason we were given for #4 is that during power transfer it is possible for the BSCU to momentarily lose power, thus rendering you brakeless (again, momentarily) which would be a bad thing in a turn. Whether that's a legitimate concern I know not.

Is it not ENG 2……SHUT DOWN then Y ELEC PUMP…..ON

[Black Pudding]

Originally Posted by Speedwinner

Question: you arrive at the gate single engine taxi in. When to switch off the elec pump? After Peking brake set or when the engines are shut down? How’s about the ptu?

Y ELEC PUMP…OFF then ENG 1…. SHUT DOWN

[sonicbum]

Originally Posted by applecrumble

Hey guys,

My operator recently changed its procedure on recommendation from Airbus. We now have to wait until we are in a straight line to operate the yellow electric pump. Anyone know as to why?
Cheers

Hi,

the aircraft should be taxied in a straight line in case NWS were to be lost during transfer of hydraulic pressure sources. You should maintain the straight line for at least 5 seconds after selecting ENG 2 master switch on to ensure PTU self test is completed.

[Bumblebee]

Originally Posted by Black Pudding

Y ELEC PUMP…OFF then ENG 1…. SHUT DOWN

Yes... but not so black and white. That is how it appears in the FCOM, however... what we often see is the PF setting the parking brake and then looking up and staring at the overhead panel waiting for the Y Elec pump to be switched off before returning their attention to shutting down Eng No1.
There should be no delay in shutting down the engine, in order to minimise risk of a roll forwards in the event of a brake failure, or to ground crew approaching the aircraft - both high risk, and not without fatal precedent.
Point being.. it doesn't really matter if the Y Elec pump is switched off before, simultaneously or after PF has shut down ENG 1, but many think that the order it's presented in the FCOM Normal Procedures means it has to be done before the Engine is shut down. May be better to consider the PF setting the parking brake is a trigger point for the PM to begin their shutdown flow..
Take a look at the Task Sharing: PRO-NOR-TSK 00024929.0004001 "At parking position:"

[sonicbum]

Originally Posted by Bumblebee

There should be no delay in shutting down the engine, in order to minimise risk of a roll forwards in the event of a brake failure, or to ground crew approaching the aircraft - both high risk, and not without fatal precedent.
Point being.. it doesn't really matter if the Y Elec pump is switched off before, simultaneously or after PF has shut down ENG 1, but many think that the order it's presented in the FCOM Normal Procedures means it has to be done before the Engine is shut down. May be better to consider the PF setting the parking brake is a trigger point for the PM to begin their shutdown flow..
Take a look at the Task Sharing: PRO-NOR-TSK 00024929.0004001 "At parking position:"

Hi,

beg to differ on the above.

The OETA is a supplementary procedure even though nowadays it is often embedded in normal SOPs within the airlines (including mine) but the actuation logic remains the one of a supp procedure.
There is no reason why You would want to shut down engine N1 "immediately" once at parking position. The risk or roll forward is mitigated by the the proper application of the parking brake (Safe aircraft parking) and the ground staff is trained not to approach the aircraft till the beacon light is switched off. Furthermore, if operating with APU inop you would have to wait till ground power is connected to shut down Engine 1 (on a side note some airports do require the port engine to be off for the ground crew to connect the external power so OETA would not be possibile if operating without APU). Bottom line is, many occasions where you could find yourself at the gate with one engine running for a handful of seconds in completely normal operations.
On the other hand, not respecting the sequence Y ELEC PUMP OFF then ENG 1 Shutdown is an incorrect application of a supplementary procedure.

[Bumblebee]

That's a fair comment, and a great example of contradiction or ambiguity in the FCOM, where the Task Sharing table clearly shows the two respective actions as simultaneous, as opposed to sequentially in PRO-NOR-SUP-ENG.
On the other hand, the two actions are not interdependent from a technical point of view, and the order in which they are carried out is entirely inconsequential. Whereas the consequences of unnecessarily delaying Engine shutdown is an increased risk factor.
There are lots of procedures where the order they are shown matters, but this isn't one of them.
I'm quite comfortable from an Airmanship point of view, of minimising risk factors when 90% of arrivals are OETA against the rare occasions that shut-down *needs* to be delayed for FEGP to be plugged in.
There is no reason to *wait* for your colleague to switch off the Y ELEC pump before shutting the engine down.

In fact, one has to ask whether it's even relevant when I'd assume that (without any specific guidance) even with the SETWA mod, OET is prohibited when:

• GEN 1 or IDG1 or APU or APU BLEED or APU GEN inoperative.
  
  Or if you're going somewhere that requires ENG 1 shutdown first for either for FEGP to be plugged in, or because of proximity to the Air-Bridge: it's definitely irrelevant because you're not going to be doing the OETA Supplementary Procedure anyway..?
  I suppose the scenario is only going to occur if you've decided to SETWA and then the APU subsequently fails to start ! (And of course....that never ever happens ...)

[sonicbum]

Originally Posted by Bumblebee

That's a fair comment, and a great example of contradiction or ambiguity in the FCOM, where the Task Sharing table clearly shows the two respective actions as simultaneous, as opposed to sequentially in PRO-NOR-SUP-ENG.

Hi,

Tasksharing does not related to supplementary procedures. You must have a specifically tailored OM-B embedding the OETA and associated actions.

Originally Posted by Bumblebee

On the other hand, the two actions are not interdependent from a technical point of view, and the order in which they are carried out is entirely inconsequential. Whereas the consequences of unnecessarily delaying Engine shutdown is an increased risk factor.
There are lots of procedures where the order they are shown matters, but this isn't one of them.
I'm quite comfortable from an Airmanship point of view, of minimising risk factors when 90% of arrivals are OETA against the rare occasions that shut-down *needs* to be delayed for FEGP to be plugged in.
There is no reason to *wait* for your colleague to switch off the Y ELEC pump before shutting the engine down.

Sorry but disagree.

You can't arbitrarily change the order of a supplementary because you believe it does not make any difference . If this is due to the fact that your tasksharing displays the actions on the same line, I suggest you drop a mail to your tech pilot and ask for a clarification. Often those issues arise at the customization phase of the document and or when converting formats to fit the different EFBs.
.

[Bumblebee]

I'd argue that in this case, tasksharing is appropriate, because it's embedded into a series of Normal Procedures - and whilst supplementary, it is not overriding.

"The FCOM also contains normal procedures that are non-routine procedures in the Supplementary Procedures chapter and in the Special Operations chapter."


Do you actually get the EFB out and 'Read and Do' the OETA Supplementary procedure, further delaying engine shutdown and placing below wing operatives at greater risk?


There is no specific tasksharing published for this procedure, so defaulting to Normal Procedures tasksharing would be quite sensible.


OM-B has nothing to do it - I don't work for a single-type Operator. Do you mean the FCTM? The AIRBUS FCTM just refers back to the FCOM Supplementary procedure....


What do you disagree with?

Do you disagree that in these circumstances, shutting the engine down and switching off the Y ELEC pump are not technically dependent on each other?

Do you disagree that the order the two actions are carried out is technically inconsequential.

Do you really disagree that delaying an engine shutdown is an increased risk factor?


You state:

The risk or roll forward is mitigated by the the proper application of the parking brake (Safe aircraft parking) and the ground staff is trained not to approach the aircraft till the beacon light is switched off.

Despite being trained not to do so, ground crew still unfortunately manage to get themselves ingested into engines, and procedural errors and technical failures still occur..

There's nothing arbitrary about it - maybe it's a considered decision I'm entitled to make as a commander, varying an SOP where safety considerations override?

Whatever order it's written down - in this circumstance it just doesn't matter...the PTU will still be barking away down the back whichever side the residual system pressure comes from.
There are probably far more important things for us to be losing sleep over....

[sonicbum]

Originally Posted by Bumblebee

I'd argue that in this case, tasksharing is appropriate, because it's embedded into a series of Normal Procedures - and whilst supplementary, it is not overriding.

"The FCOM also contains normal procedures that are non-routine procedures in the Supplementary Procedures chapter and in the Special Operations chapter."


Do you actually get the EFB out and 'Read and Do' the OETA Supplementary procedure, further delaying engine shutdown and placing below wing operatives at greater risk?


There is no specific tasksharing published for this procedure, so defaulting to Normal Procedures tasksharing would be quite sensible.


OM-B has nothing to do it - I don't work for a single-type Operator. Do you mean the FCTM? The AIRBUS FCTM just refers back to the FCOM Supplementary procedure....


What do you disagree with?

Do you disagree that in these circumstances, shutting the engine down and switching off the Y ELEC pump are not technically dependent on each other?

Do you disagree that the order the two actions are carried out is technically inconsequential.

Do you really disagree that delaying an engine shutdown is an increased risk factor?


You state:




Despite being trained not to do so, ground crew still unfortunately manage to get themselves ingested into engines, and procedural errors and technical failures still occur..

There's nothing arbitrary about it - maybe it's a considered decision I'm entitled to make as a commander, varying an SOP where safety considerations override?

Whatever order it's written down - in this circumstance it just doesn't matter...the PTU will still be barking away down the back whichever side the residual system pressure comes from.
There are probably far more important things for us to be losing sleep over....

Hi,

I will rephrase it.

If you apply the Airbus standard, not airline specific, the OETD/OETA is a supplementary procedure and will be treated as such, as described in the FCTM AOP->Tasksharing rules and communication. Read and Do Principle, no actions from memory.
You will not find those actions within the FCOM -> Normal Procedures -> Tasksharing as this section deals with SOPs flows and as we said the above is a read and do.
So you will have to read and do and follow the Supplementary Procedure in order to comply.

Having said that, many operators customize their procedures to different extents. The most common one is probably embedding the OETD/OETA supplementary into the SOPs flows, so that the crew will apply the actions from memory without treating it as a supplementary procedure. Usually a risk assessment is conducted depending on the airline familiarity with the type and the number of sectors flown daily to assess if it is worth it or not. Where I work, OETD/OETA is applied as a normal SOP flow but this is reflected in a document called "OM-B", that is under the EASA nomenclature "Airplane operating matters". It is basically how the airline adjusts the normal, supplementary, special, limitations etc.. according to the Operator's needs and will often differ from what is written in the Airbus "pure" FCOM.

Bottom line is: how you will execute a certain type of procedure mainly depends on what is written in your books. I have the "luxury" of starting Engine 2 during taxi from memory and shutting it down as well because this is how it is coded in our lot. Our checklists are modified as well to make sure we do not forget some stuff on the way...
But if this was not the case we would read and do the procedure every single time, 4 times a day, like we used to till about 10 years ago (if memory serves, maybe more) when we treated the OETD/OETA as a pure supplementary procedure.

Hope this helps.

[sonicbum]

Originally Posted by Bumblebee

I'd argue that in this case, tasksharing is appropriate, because it's embedded into a series of Normal Procedures - and whilst supplementary, it is not overriding.

"The FCOM also contains normal procedures that are non-routine procedures in the Supplementary Procedures chapter and in the Special Operations chapter."


Do you actually get the EFB out and 'Read and Do' the OETA Supplementary procedure, further delaying engine shutdown and placing below wing operatives at greater risk?


There is no specific tasksharing published for this procedure, so defaulting to Normal Procedures tasksharing would be quite sensible.


OM-B has nothing to do it - I don't work for a single-type Operator. Do you mean the FCTM? The AIRBUS FCTM just refers back to the FCOM Supplementary procedure....


What do you disagree with?

Do you disagree that in these circumstances, shutting the engine down and switching off the Y ELEC pump are not technically dependent on each other?

Do you disagree that the order the two actions are carried out is technically inconsequential.

Do you really disagree that delaying an engine shutdown is an increased risk factor?


You state:




Despite being trained not to do so, ground crew still unfortunately manage to get themselves ingested into engines, and procedural errors and technical failures still occur..

There's nothing arbitrary about it - maybe it's a considered decision I'm entitled to make as a commander, varying an SOP where safety considerations override?

Whatever order it's written down - in this circumstance it just doesn't matter...the PTU will still be barking away down the back whichever side the residual system pressure comes from.
There are probably far more important things for us to be losing sleep over....

Hi,

I will rephrase it.

If you apply the Airbus standard, not airline specific, the OETD/OETA is a supplementary procedure and will be treated as such, as described in the FCTM AOP->Tasksharing rules and communication. Read and Do Principle, no actions from memory.
You will not find those actions within the FCOM -> Normal Procedures -> Tasksharing as this section deals with SOPs flows and as we said the above is a read and do.
So you will have to read and do and follow the Supplementary Procedure in order to comply.

Having said that, many operators customize their procedures to different extents. The most common one is probably embedding the OETD/OETA supplementary into the SOPs flows, so that the crew will apply the actions from memory without treating it as a supplementary procedure. Usually a risk assessment is conducted depending on the airline familiarity with the type and the number of sectors flown daily to assess if it is worth it or not. Where I work, OETD/OETA is applied as a normal SOP flow but this is reflected in a document called "OM-B", that is under the EASA nomenclature "Airplane operating matters". It is basically how the airline adjusts the normal, supplementary, special, limitations etc.. according to the Operator's needs and will often differ from what is written in the Airbus "pure" FCOM.

Bottom line is: how you will execute a certain type of procedure mainly depends on what is written in your books. I have the "luxury" of starting Engine 2 during taxi from memory and shutting it down as well because this is how it is coded in our lot. Our checklists are modified as well to make sure we do not forget some stuff on the way...
But if this was not the case we would read and do the procedure every single time, 4 times a day, like we used to till about 10 years ago (if memory serves, maybe more) when we treated the OETD/OETA as a pure supplementary procedure.

Hope this helps.

[sonicbum]

Originally Posted by Bumblebee

I'd argue that in this case, tasksharing is appropriate, because it's embedded into a series of Normal Procedures - and whilst supplementary, it is not overriding.

"The FCOM also contains normal procedures that are non-routine procedures in the Supplementary Procedures chapter and in the Special Operations chapter."


Do you actually get the EFB out and 'Read and Do' the OETA Supplementary procedure, further delaying engine shutdown and placing below wing operatives at greater risk?


There is no specific tasksharing published for this procedure, so defaulting to Normal Procedures tasksharing would be quite sensible.


OM-B has nothing to do it - I don't work for a single-type Operator. Do you mean the FCTM? The AIRBUS FCTM just refers back to the FCOM Supplementary procedure....


What do you disagree with?

Do you disagree that in these circumstances, shutting the engine down and switching off the Y ELEC pump are not technically dependent on each other?

Do you disagree that the order the two actions are carried out is technically inconsequential.

Do you really disagree that delaying an engine shutdown is an increased risk factor?


You state:




Despite being trained not to do so, ground crew still unfortunately manage to get themselves ingested into engines, and procedural errors and technical failures still occur..

There's nothing arbitrary about it - maybe it's a considered decision I'm entitled to make as a commander, varying an SOP where safety considerations override?

Whatever order it's written down - in this circumstance it just doesn't matter...the PTU will still be barking away down the back whichever side the residual system pressure comes from.
There are probably far more important things for us to be losing sleep over....

Hi,

I will rephrase it.

If you apply the Airbus standard, not airline specific, the OETD/OETA is a supplementary procedure and will be treated as such, as described in the FCTM AOP->Tasksharing rules and communication. Read and Do Principle, no actions from memory.
You will not find those actions within the FCOM -> Normal Procedures -> Tasksharing as this section deals with SOPs flows and as we said the above is a read and do supp.
So you will have to read and do and follow the Supplementary Procedure in order to comply.

Having said that, many operators customize their procedures to different extents. The most common one is probably embedding the OETD/OETA supplementary into the SOPs flows, so that the crew will apply the actions from memory without treating it as a supplementary procedure. Usually a risk assessment is conducted depending on the airline familiarity with the type and the number of sectors flown daily to assess if it is worth it or not. Where I work, OETD/OETA is applied as a normal SOP flow but this is reflected in a document called "OM-B", that is under the EASA nomenclature "Airplane operating matters". It is basically how the airline adjusts the normal, supplementary, special, limitations etc.. according to the Operator's needs and will often differ from what is written in the Airbus "pure" FCOM.

Bottom line is: how you will execute a certain type of procedure mainly depends on what is written in your books. I have the "luxury" of starting Engine 2 during taxi from memory and shutting it down as well because this is how it is coded in our lot. Our checklists are modified as well to make sure we do not forget some stuff on the way...
But if this was not the case we would read and do the procedure every single time, 4 times a day, like we used to till about 10 years ago (if memory serves, maybe more) when we treated the OETD/OETA as a pure supplementary procedure.

Hope this helps.

[Zar_1]

Originally Posted by Amadis of Gaul

3. APU AVAIL light is on (because our birds don't have that much-discussed mod);

Which modification is that?