Regarding APU

[711Hancer]

Im currently confused with recent updates on most people's invaluable checklists regarding engine start procedures and follow-ups.

 

In some checklists they turn EGI and CDU after cranking the left engine.

They turn APU off after running on left engine..

 

some turn apu off after starting up the two engines etc.

 

following this picture;

 

http://farm5.static.flickr.com/4144/4996069258_b41d602b89_o.jpg

 

it is seen clearly that this guy did not shut the APU. He completed his INS alignment so nearly 5 mins passed after engine start-up. APU GEN warning light is lit.

 

I wonder when to shut APU and engage AC generators etc. Can someone clarify the process?

Also after the recent patch the master caution light is lit when APU GEN is ON when engines running and you engage AC generators. So our guy in this pic is must have this kind of warning tone?

 

 

 

anyways.. a great pic btw :)

[LostOblivion]

To my knowledge, you cannot start any engine on the ground without bleed air from the APU, meaning it'll have to remain on until both engines are running.

 

Picture taken at Martin State Airport.

 

http://maps.google.com/maps?q=N39+20.110+W076+25.255&hl=no&ll=39.337252,-76.420748&spn=0.007659,0.013078&sll=39.335714,-76.427082&sspn=0.007659,0.013078&vpsrc=0&t=h&z=17

Edited August 16, 2011 by LostOblivion

[EtherealN]

Actually, that light only means he didn't turn off the APU generator.

It will be lit whenever the generator is turned on - it doesn't need the APU itself to be on.

[711Hancer]

Yes but what Im asking here is why is he keeping his APU on?

I mean engines running AC generators on.. why APU itself and APU gen is remained ON? Even after completion of the alignment

[EtherealN]

My point is - we don't know that his APU is on. His APU Gen is on. This doesn't mean APU is on.

 

As for why - he might have forgotten it. Happens. :)

[711Hancer]

My point is - we don't know that his APU is on. His APU Gen is on. This doesn't mean APU is on.

 

As for why - he might have forgotten it. Happens. :)

 

 

Check engine instruments

 

his APU is ON.

 

This is what confuses me. Why? :) do we need to revise our checklists? :)

[EtherealN]

Nevermind, I'm blind - his APU is on (seen on the dials).

[nomdeplume]

Maybe he forgot? I'd guess he's not finished starting up though, e.g. the ejection seat is apparently not armed yet (I thought they were meant to do that first thing in case they have to make a rapid exit during the startup procedure).

 

May just be personal preference. Keeping the APU running and generator enabled gives you a backup power source if you suddenly need to shut down the engines. You're unlikely to encounter such a situation within the sim though, as far as I know... random engine fire at startup?

[Frostiken]

APU is running - look at the gauges.

 

And no, it doesn't mean 5 minutes have passed - in real life startup procedures tend to be a little slower than how fast you can blast through it in the sim - the crew chief has to check for various serving on the engines and such. So 4.1 minutes, minus the time for engines to spool up since you can power it all off the APU gen alone.

 

Regardless, there's a couple reasons real-life that this could've happened, most notably a redball for something that delayed the second engine start.

 

Mostly what I'm curious about is who's standing in front of running engines snapping pictures over the top rail of the A-10? It's not like it's low to the ground and you can just lean over.

 

Maybe he forgot? I'd guess he's not finished starting up though, e.g. the ejection seat is apparently not armed yet (I thought they were meant to do that first thing in case they have to make a rapid exit during the startup procedure).

IIRC the ejection seat is inoperative while the canopy is open. The canopy simply doesn't jettison right when it's open, not to mention there could be a canopy brace installed as well, so either way you're going to get your shit ruined by hitting the metal frame. Don't quote me on this though, just something I've heard (and it makes sense). Edited August 16, 2011 by Frostiken

[711Hancer]

Mostly what I'm curious about is who's standing in front of running engines snapping pictures over the top rail of the A-10? It's not like it's low to the ground and you can just lean over.

 

Yea a really weird pic :)

 

IIRC the ejection seat is inoperative while the canopy is open. The canopy simply doesn't jettison right when it's open, not to mention there could be a canopy brace installed as well, so either way you're going to get your shit ruined by hitting the metal frame. Don't quote me on this though, just something I've heard (and it makes sense).

 

So true.

 

So what Im saying here is that maybe we should revise our checklists and keep APU on after engine startup and turn it off when we are sure that engines operate smoothly.

 

Im against the checklists where people even shut down the APU after successfully cranking the left engine.

[Kaiza]

Check engine instruments

 

his APU is ON.

 

This is what confuses me. Why? :) do we need to revise our checklists? :)

 

Not sure what checklists you are refereing to but check out Paulrkiiis checklists. The APU is secured well after engine start in these, (which are based on real A-10C checklists).

 

http://forums.eagle.ru/attachment.php?attachmentid=54622&stc=1&d=1312206111

 

I know very little about the A-10, however in aircraft types I am familiar with the APU is generally one of the last things to be secured before taxi as it minimises bus power transfers while other equipment is running BITs and being powered up. Having a quick look at the electrical diagram in the manual supplements on page 658, it suggests that some of the DC buses are powered when the APU is on (right DC Bus) even when the engine driven generators are online. So if you secure the APU then power to this bus will be transferred from the APU to the right engine causing a momentary spike . This is something you do not want to do until everything is powered up and stable.

 

Pretty minor though I am sure there are a thousand things that are done differently in the sim vs RL.

Edited August 16, 2011 by Kaiza

[JCav]

While at Cheyenne Frontier Days Air Show on July 27th, I was standing near the A-10C East Demo team while they started both aircraft. The APU was definitely on for a long while after both engines were running (it was a much louder sound than the engines so I could tell when it started and ended).

 

They also did not lower their canopy until after proceeding a bit down the taxiway.

[711Hancer]

Hmm thank you for the checklist.

 

I agree with your opinions regarding the APU.

 

I also like to note that in RL generally canopy remains open as well, whereas in some sim operations ppl immediately close the canopy even before apu and engine start.

 

Being an old fox PMDG 737 simmer, sometimes we all want to do things like real pilots do and eager to search for any additional little detail that we might miss in our sim operations. Its always nice to learn and by looking at this picture, this sim is surely GREAT!

Edited August 16, 2011 by 711Hancer

[Kaiza]

Being an old fox PMDG 737 simmer, sometimes we all want to do things like real pilots do and eager to search for any additional little detail that we might miss in our sim operations. Its always nice to learn and by looking at this picture, this sim is surely GREAT!

 

Sweet man. If that's the case check out the rest of Paulrkiiis guides then (if you havent already), they all stem from real SOPs.

 

http://forums.eagle.ru/showthread.php?t=77053

[Frostiken]

They also did not lower their canopy until after proceeding a bit down the taxiway.

 

The reason for this is that the ECS system in the A-10 doesn't generate shit for bleed air when the engines are operating at low power, so little that they don't even get airflow to the cockpit. The reason they taxi with the canopy open, and crack it open right after they land is because it gets hot as hell in there with it closed.

 

sometimes we all want to do things like real pilots do and eager to search for any additional little detail that we might miss in our sim operations

Well my stance on this is that not everything pilots do is right, not all checklists are always the best thing to follow*, and like all pilots, you should have your own way of doing things. Some people seem to be under the impression that a startup checklist is some sort of Biblical text and must be adhered to, when real life pilots do all kinds of their own shit.

 

Really, these are pilots we're talking about - You shouldn't always think that what you see a pilot do is the correct way to do things, or that they always know exactly what's going on. Case in point, I just got back from a TDY and had a few beers with the guy who turned this into this. PS: Check out the ICMS system - the Band 3 C/O standing upright, completely beat to crap, and the Band 1.5 C/O ballast, totally unscathed next to it :D

 

* By this I mean you can infer a lot from the steps a checklist is ordered in, but it's not always correct to assume. Many times steps are simply placed ambiguously. As a more trivial example, you can uncage your SADI the second you get in the cockpit, it really doesn't matter when you do it.

Edited August 16, 2011 by Frostiken

[Snoopy]

Yes but what Im asking here is why is he keeping his APU on?

I mean engines running AC generators on.. why APU itself and APU gen is remained ON? Even after completion of the alignment

 

 

Once both engines are up and stable you don't need the APU on. The only reason pilots leave it on is for heating or air conditioning. Believe it or not the APU produces more bleed air there for heating/air conditioning is stronger with the APU running.