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What is the reason for turning off fuel pumps after shutdown.(a320)

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What is the reason for turning off fuel pumps after shutdown.(a320)

Old 12th Jun 2020, 11:13
  #41 (permalink)  

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Depends on the routes. CDG-FRA-CDG-AMS-CDG-MAN (or similar) those extra 5 minutes on the ground do make a lot of difference. For SOF-STR-SOF-KBP-SOF, hell yes why not keep one engine running.
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Old 12th Jun 2020, 12:44
  #42 (permalink)  
 
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Re cockpit preparation; we used to do everything else, but we would leave the fuel pumps off.

Just before PF called for the Before Start checklist, they would double check the overhead panel for any white lights and put the pumps on then. And start the APU as well, if it had not been started already.

Can't remember if this was our Airline SOPs or just something we did.
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Old 12th Jun 2020, 13:30
  #43 (permalink)  
 
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Originally Posted by AerocatS2A View Post
To each, their own. Personally I'd much rather do a four sector day with minimum turn times rather than have a five to ten minute lull each time. Get to work, bang out the sectors, go home, that's my ideal work schedule.
Absolutely, i rather do four short domestic sectors than a 5 hour out and back day. Even better if they switch to just two short domestic sectors

Re cockpit preparation; we used to do everything else, but we would leave the fuel pumps off.

Just before PF called for the Before Start checklist, they would double check the overhead panel for any white lights and put the pumps on then. And start the APU as well, if it had not been started already.

Can't remember if this was our Airline SOPs or just something we did.


Sounds sensible.
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Old 12th Jun 2020, 14:46
  #44 (permalink)  
 
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Thanks guys. Really eye opening. Very different operating culture on this side of the Atlantic. We’re not usually as concerned about departure time- then again the cockpit crew isn’t usually the time limiting factor in our turns.
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Old 12th Jun 2020, 16:27
  #45 (permalink)  

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Originally Posted by Check Airman View Post
Really eye opening. Very different operating culture on this side of the Atlantic.
I'd bet you won't find an aspect of the job we did not manage to make less rewarding or more demanding.
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Old 13th Jun 2020, 06:35
  #46 (permalink)  
 
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Originally Posted by FlightDetent View Post
I'd bet you won't find an aspect of the job we did not manage to make less rewarding or more demanding.
I wouldn't say that. It's my understanding that you guys don't usually do overnights on narrowbodies. I find that very appealing. At most airlines in the US, that kind of flying is very senior. Many people will bypass upgrading to captain or larger airplane in order to enjoy being home every night.

I also think commuting is less prevalent across the ocean. That's immensely stressful.
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Old 13th Jun 2020, 07:09
  #47 (permalink)  
 
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Originally Posted by Check Airman View Post
I wouldn't say that. It's my understanding that you guys don't usually do overnights on narrowbodies. I find that very appealing. At most airlines in the US, that kind of flying is very senior. Many people will bypass upgrading to captain or larger airplane in order to enjoy being home every night.

I also think commuting is less prevalent across the ocean. That's immensely stressful.
We do at Legacies ; rosters are pretty much always 3 to 5 days trips on short - medium haul and the same (obviously) on long haul. LCC's have a different business model with a multi base scheme, that is why they rarely go on layover.
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Old 13th Jun 2020, 09:23
  #48 (permalink)  
 
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Originally Posted by Check Airman View Post
I wouldn't say that. It's my understanding that you guys don't usually do overnights on narrowbodies. I find that very appealing. At most airlines in the US, that kind of flying is very senior. Many people will bypass upgrading to captain or larger airplane in order to enjoy being home every night.

I also think commuting is less prevalent across the ocean. That's immensely stressful.
It depends. As sonicbum has mentioned it is quite common in legacy carriers to be on the road for a few days, between 2 and 6 on narrowbodies and up to 15 days on widebodies. But yes, LCCs usually have a multibase strategy and try to plan without layovers as much as possible. And i honestly didn't know the difference until i switched from legacy to lcc. Now i jump on my bike, cycle to the airport, fly a few hours, cycle back and enjoy my own life at home. Whereas before i always had to pack my suitcase, get it to the airport, sleep in horrible hotels if sleeping is possible at all and usually do a shift pattern change during every rotation (early to late or late to early). Of course a fixed roster pattern, which is quite common in LCCs, does help a lot too for quality of life. The difference is of course hub based traffic vs pure point to point connections.

Commuting is not as easy on this side of the atlantic. That said, it is still done a lot. However, as many options include paying for the fun of it there is not only the loss in quality of life to consider, but also the financial implications that effectively reduce your take home pay, even if it is tax deductible.
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Old 15th Jun 2020, 04:54
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Originally Posted by jettison valve View Post
Dear tdracer,
As was pointed out already, on A330/A340s (I think A380 is the same) the ENG master switch closes also the LP valve on the front spar. Unless... it´s assembled wrongly, as a hidden failure.
This lesson was learned when during a maintenance activity (for whatever reason!) an engine was to be shut down using just the ENG Fire P/B (which interestingly only moves the LP valve, but does not trigger the HMU or anything else in ATA 73). The engine kept on running for many minutes, when the engineers finally killed the engine with the ENG master switch.
Side facts: The incident took place on an A340 whose "operator" at that time was, well, a big aircraft manufacturer in Seattle. Secondly, we replicated the same scenario (eng shutdown via fire P/B) on a different airplane, and it took more than 60sec before the EGT started decreasing after P/B activation; I still wonder why it takes so long...

J. V.

It takes about a minute of idle operation for the engine to flame out after closing the spar valve or LP fuel valve only (not the HP valve in the engine HMU) because that's how long it takes to suck the remaining fuel out of the fuel line between the LP valve on the rear spar and the fuel pump to the point where LP stage of the fuel pump receives excessive vapor and sends vapor to the HP pump. It takes a similar amount of time on the Boeing airplanes.
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Old 15th Jun 2020, 21:10
  #50 (permalink)  
 
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Originally Posted by Dave Therhino View Post
It takes about a minute of idle operation for the engine to flame out after closing the spar valve or LP fuel valve only (not the HP valve in the engine HMU) because that's how long it takes to suck the remaining fuel out of the fuel line between the LP valve on the rear spar and the fuel pump to the point where LP stage of the fuel pump receives excessive vapor and sends vapor to the HP pump. It takes a similar amount of time on the Boeing airplanes.
Hi Dave,
I agree as to where the fuel comes from - but my real question is: What "replaces" this fuel, in other words: what happens to the space where the fuel is taken from by the engine?
Assuming that the LP valve and the tubing between the LP valve and the HMU has no leaks, there would be a SIGNIFICANT vacuum in the lines...? Wouldn´t that trigger leaks afterwards as the tubes are designed for "outward" pressure, not an internal vacuum?
Regards, J. V.
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Old 15th Jun 2020, 21:35
  #51 (permalink)  
 
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Originally Posted by jettison valve View Post
Hi Dave,
I agree as to where the fuel comes from - but my real question is: What "replaces" this fuel, in other words: what happens to the space where the fuel is taken from by the engine?
Assuming that the LP valve and the tubing between the LP valve and the HMU has no leaks, there would be a SIGNIFICANT vacuum in the lines...? Wouldn´t that trigger leaks afterwards as the tubes are designed for "outward" pressure, not an internal vacuum?
Regards, J. V.
With the spar valve closed, the main engine fuel pump is basically doing a 'suction feed' of what's in the pipe downstream of the spar valve. So what's filling in the extra space is fuel vapor - in a sense the fuel in the line starts to boil due to the suction of the fuel pump. Eventually the fuel pump cavitates and can't provide sufficient fuel pressure to keep the engine running and it quits. A minute for that to happen is pretty average - although it can go anywhere from about 30 seconds to two minutes depending on the volume of the pipe and the idle fuel flow of the engine.
Oh, and thanks for the kind words.
BTW, I'm a bit surprised that no one has mentioned the possibility of running a fuel pump in an empty tank as a reason to shutdown the fuel pumps. If the fuel tank is nearly empty, and the fuel pumps are merrily running with no fuel actually being pumped, it's possible for the fuel pump to overheat. Now, the fuel pumps are designed not to overheat in that scenario, but just like anything else fuel pumps wear and deteriorate - and have been known to fail in such a way that they do overheat to the point that they become a potential ignition source.
No idea of that's part of the Airbus thinking, but I do know that's why - at least on Boeing's - you're instructed to turn off the center tank fuel pumps as soon as the tank is nearly empty and you get the low pump pressure indications.
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Old 16th Jun 2020, 00:39
  #52 (permalink)  

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Center tanks pumps switch off too on AB without fuel. more explicitly they won't engage in an empty tank.

The issue of the thread is reading the AB FCOM which instructs pilots to turn the fuel pumps on, during cockpit prep, without telling them this is only to be done after the refuelling.
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Old 26th Aug 2020, 15:20
  #53 (permalink)  
 
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walkaround

Dear mates,
Just a quick chat, please, do you know if the Red Beacon Lights are required to be turned ON during walkaround procedures?
My question is that this light could halt ground personal around aircraft safe area.
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Old 26th Aug 2020, 15:45
  #54 (permalink)  
 
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Never noticed any operator employ this SOP. At my old airline, they wouldn’t approach the plane until the beacon was off. (current airline- they’ll have the cargo door open before you even get a chance to reach for the beacon )
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Old 26th Aug 2020, 19:49
  #55 (permalink)  

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Originally Posted by Connie Wings View Post
Dear mates,
Just a quick chat, please, do you know if the Red Beacon Lights are required to be turned ON during walkaround procedures?
My question is that this light could halt ground personal around aircraft safe area.
More worryingly, this could teach the ground personnel to ignore the beacon light.

The logical question how do we check the beacon has a simple answer: the engineers would on a daily basis. Should it break mid-day, the redcap is sure to tell you and MMEL relief is available.

That itself is a good marker if you really need to verify its operation as a pilot before each flight. Items dispatchable i.a.w. MMEL are those, where another independent failure on the same system won't directly jeopardise the safe outcome. I.e. systems you can afford to lose with 2 levels of protection then remaining.

Simply put, for MMELable items it is OK to wait until they fail, no need to verify beforehand. As a general concept.

​​​​


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Old 26th Aug 2020, 20:43
  #56 (permalink)  
 
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Originally Posted by FlightDetent View Post
More worryingly, this could teach the ground personnel to ignore the beacon light.

The logical question how do we check the beacon has a simple answer: the engineers would on a daily basis. Should it break mid-day, the redcap is sure to tell you and MMEL relief is available.

That itself is a good marker if you really need to verify its operation as a pilot before each flight. Items dispatchable i.a.w. MMEL are those, where another independent failure on the same system won't directly jeopardise the safe outcome. I.e. systems you can afford to lose with 2 levels of protection then remaining.

Simply put, for MMELable items it is OK to wait until they fail, no need to verify beforehand. As a general concept.

​​​​
Thanks, FlightDetent. My question was not so clear.
What I was trying to bring to chat is just that: - If Red Beacon lights need to be "ON" during external lights check.
I agree to your answer.
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Old 27th Aug 2020, 14:13
  #57 (permalink)  
 
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Originally Posted by Connie Wings View Post
Thanks, FlightDetent. My question was not so clear.
What I was trying to bring to chat is just that: - If Red Beacon lights need to be "ON" during external lights check.
I agree to your answer.
No, it is a maintenance task to check both upper and lower beacon lights. During the external walkaround You check on the lower center fuselage that the beacon light is in place and not damaged.
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Old 28th Aug 2020, 16:42
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Originally Posted by sonicbum View Post
No, it is a maintenance task to check both upper and lower beacon lights. During the external walkaround You check on the lower center fuselage that the beacon light is in place and not damaged.
Appreciate chat, Sonicbum.
My conclusion is that, even though some commercial airlines require external lights check during walk around, totally agree that red beacon and strobe lights should be checked by maintenance or, red cap shall tell us if it's not working.

Many Thanks
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Old 11th Sep 2020, 14:46
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Originally Posted by Jwscud View Post
There is nothing in our SOPs either.

There is howver plenty of “wise man’s guidance” from our training dept. My lot have a number of EIS1 old MSNs in the 1xxx range and I was strongly advised not to switch the pumps on until:
(a) refuelling was complete and
(b) the APU was running and the external power had been disconnected.

The reasoning behind the latter was experience showed most “challenging” problems (random ECAMs, CIDS issues requiring resets &c happened when switching power supplies with a high load. Not SOP or in the manuals but wise experience nonetheless!
Probably applicable to very old MSNs. However, the reasons for doing this are no longer applicable
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Old 11th Sep 2020, 14:52
  #60 (permalink)  
 
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Originally Posted by Uplinker View Post
Re cockpit preparation; we used to do everything else, but we would leave the fuel pumps off.

Just before PF called for the Before Start checklist, they would double check the overhead panel for any white lights and put the pumps on then. And start the APU as well, if it had not been started already.

Can't remember if this was our Airline SOPs or just something we did.
Big Airways pilots did a combination of both. It was clarified a few years ago. White lights out on preparation.
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