Hello,

how does the high pressure start work? I tried to start with engine 3 first, but no success...

It appears that using High Pressure to start the engines isn't working when on the ground. But you can use it to start the engines in flight. I tried it. ;)

This could also explain why GRD START is above the Low Pressure!

Mark

Low pressure start is for ground start  and high pressure start is for air start .

High Pressure starts on the ground work just fine for me?

1.  Battery On, Parking Brake on (CTRL + .)
2.  Make sure power and air are ON (shift 2 panel)
3.  Turn the switch to EXT POWER (not sure it's label, below the ground power switch on the FE's upper panel).  You should see air pressure rise and electric turn on.  Be sure the DC bus is on ESS.
4.  Open the cover switch and select HIGH PRESS (overhead between engine start switches).
5.  Switch engine 3 to GRD
6.  Watch for about 18% N2
7.  Introduce fuel
8.  Once engine starts and stabilizes, go and switch the switch in #3 to Gen 3, and then switch the switch in 4 to LOW press.
9.  Start eng 4, 1 and then 2....

Thats a quick one off the top of my head?!

There is very helpful KB entry on how to start all engines manually - check-in to Your Profile and use Customer Support > Search KB > KB# 6204.

Captain Sim 2 wrote on Oct 25^th, 2010 at 7:18am:

There is very helpful KB entry on how to start all engines manually - check-in to Your Profile and use Customer Support > Search KB > KB# 6204.

Hi Tanya.

Thank you for that. I'll check it out.

BTW. It's great to see a face to go with your Forum name as well as you adding your real name to your signature. Nice touch. Makes it more person to person! [smiley=thumbsup.gif]

Mark

Hey Mark...I agree, it is wonderful to see that smiling face.

BTW I have had no problems starting with the bottle or the ground start cart.

I've been on a cross country train trip through the Rocky Mountains for the last 12 days - it is good to get home.

Also, I up-graded to Windows 7U and switched to a solid state hard drive. Very fast!  :D

Lou

Quote:

BTW I have had no problems starting with the bottle or the ground start cart.

I must be missing something here. What do you mean "the bottle"?

Mark

Markoz wrote on Oct 25^th, 2010 at 11:31pm:

BTW. It's great to see a face to go with your Forum name as well as you adding your real name to your signature. Nice touch. Makes it more person to person! [smiley=thumbsup.gif] Mark

Thank you :)

Mark,
The start cart is the unit that provides start air to all engines. The cart is plugged into the aircraft and provides low pressure (high volume) start air. The high pressure (bottle) is only able to start # 3 engine - and you get only one shot.

On the overhead panel you select the start air you want with the switch in the middle of the start panel.

I'm on my way out the door, but I'll look for the procedure in the manual later.

Lou

Quote:

The high pressure (bottle) is only able to start # 3 engine - and you get only one shot.

Lou, you've made my day with this statement. Now I know why I get that "L. H. Bottle" warning, I've used up my one shot.

I'm just wondering why I used the "high press" setting all the time.

Quote:

The normal engine starting sequence is 3, 4, 2, 1.

and I think i didn't get the No.3 engine to move with the "low press" setting in the 1.0 release.
Might be I'm confused now and I have to check this in the simulator again.

Edited:
KB 6204 seemed wrong to me but now I came across the difference to the manuals.
The KB thing describes a start sequence without external sources (and therefor "high pressure" usage) while the manuals describe the far more common ground source based start, using external power and air together with "low pressure".

If you follow the KB 6204 list, you blow off that one shot of the L. H. Bottle and receive the warning, perfectly normal and correct.

Hi Lou.

So that means that the L.H. Bottle Inactive Light should come on (and stay on), once you have started engine #3 on High Pressure? That would certainly make a lot of sense. I just didn't know that that is what the bottle was used for.

I have another question. What are the circumstances that would require a High Pressure start? Or. Did they refill the bottle after the end of every flight (where the engines were shut down) so it was always available for the engine start?

I'm guessing, that part of the answer would be that a High Pressure start should/would almost guarantee a successful engine start compared to a Low Pressure start.

Why is the engine start 3, 4, 1, 2? And is it always in that order?

Mark

Hi Mark,

I believe that the bottle (containing high pressure air) is used to start the #3 engine when a ground power/air cart was not available or not working. Then, once #3 was running, you would use the blead air from #3 to start the remaining engines. The light would come on and remain on because you discharged the bottle and ground crew would have to recharge or replace the bottle again.
Normally, you would use low pressure (ground cart) to start #3. The bottle would not come into play then.

Maybe Lou are some one else can correct me if I"m wrong, as I'm not a real pilot.

Rick

I have to correct two things. First, Mark, the sequence is 3,4,2,1 and second, I just read that high pressure start air really comes at values of 2.700 and more PSI.
So disregard my statements towards such high values being wrong. Maybe I'll edit my posts then.  :-[ (done)


I think you go for the inboards (3 and 2) first because of the shorter supply ways of the external air connected (which often has a central point of connecting to the plane) or even the high pressure bottle.
External stuff usually has one contact point and then gets distributed inside the planes structure so the delivery ways differ in length. Length causes a loss of air pressure, so the shortest way has to be preferred.

If they are running then, pressure can be supplied more stable and reliable to the outer engines being self-sustaining then.

Outboard first might work too but as you have to start the inboards anyway, use them first as their supply will usually get the required "N"-values faster, more stable and with the mentioned shorter air supply ways.

So whatever happens, start the inboard ones first, must not be the No.3 then. The side might depend on the placement of ground vehicles, carts and personnel.
Our 707 gets started on the ramp, so obstacles and people are quite close to it.
"Did anybody see the guy with the Chocks?" "Yeah, he's stuck in engine No. 3!".  ;D

If it was a special need to go for the right inboard on the 707 first (meaning No.3 then), this might be explained with the external air cart to connect nearer to the No.3 than to the No.2 engine. Same "shorter ways" theory to apply then.

I don't see any special equipment reason to start 3 before 2 as they are connected to similar systems.
Other planes might need a yellow hydraulic circuit first or such things and therefor prefer special engine numbers to be started before the others. The 707 has some special equipment (the Air Compressors) but this is spread across No. 2,3 and 4.

Maybe Lou can help here.

I stand corrected on the engine start sequence as it is 3,4,2,1. It's a bit like the firing sequence of a four cylinder engine, I always mix it up! :D

If it is inboard engines first, why do we go from 3 to 4 and not 3 to 2? This would make the engine start 3, 2, 4, 1, or even 3, 2, 1, 4. Now if we were to use an engine start example from the C-130, it is 3, 4, 1, 2 and the start cart is right near the #2 props. Not a good place to on an engine start, so the idea is that by the time engine 2 gets started the cart (and ground crew) is well away. The cart is always there because the external connectors are on that side of the fuselage. Perhaps this same type of situation applies to the 707. Food for thought!

Mark

Well, in my theory, the 4 after 3 makes sense. If 3 is running, the ways to supply 4 are short. Shorter than going for the 2.
"Inboards first" means "initially first" then.

I can't say anything about the C130, I don't own it.
But, as said, some aircraft require a certain sequence because of the equipment attached to certain engines only. I don't know about the C130 but there are other birds around that need their utility hydraulics stuff or brake circuits to be powered first, so the external crew can disconnect and the plane gets self-sustaining.

All APU driven ones are self-sustaining of course (if they use their APU), birds like this 707 or a Concorde are not and you don't want to have them on the ramp with all engines running for various reasons.
So you usually target for the self-sustaining aspect first and then push the thing off the ramp without the need to counteract the idle thrust of too much engines and without a too big danger for people and vehicles close to turning blades.

I could think of a Prop like the C130 being less "stable pressure" depended than the 707 and therefor the placement of the actual external air connector might no be as important as on the 707.

Hi Mark,

I believe that the bottle (containing high pressure air) is used to start the #3 engine when a ground power/air cart was not available or not working. Then, once #3 was running, you would use the blead air from #3 to start the remaining engines. The light would come on and remain on because you discharged the bottle and ground crew would have to recharge or replace the bottle again.
Normally, you would use low pressure (ground cart) to start #3. The bottle would not come into play then.

Maybe Lou are some one else can correct me if I"m wrong, as I'm not a real pilot.

Rick

Rick is correct. The high pressure bottle was used only as a last resort at some out station where start carts were not available. With the high pressure start you could start on only the battery for ignition. In all the years I flew the 707, the only time we used the bottle was in the simulator. If anything went wrong with the start ( hot, hung, no ignition etc.) you had no way to clear the engine. With the start cart air available, you could motor the engine to clear out the hot gases or raw fuel.

Now for the start sequence. Engine start was sometimes controlled by Jetway placement, bag loading, etc. If the front (L1) door was still opened we would not start 1 or 2 because of the noise. It did not matter which engine you start first, however only engine 1,2 & 3 had turbo compressors so you would rarely start 4 first in case the cart would die. Some (very few) 707 had 4 turbo compressors. Also, you would delay start on an engine that did not have a working generator for the same reason - in case the ground power would quit - which they did often.

Thanks for your answer, Lou. Always interesting readings.

Hi Lou.

Thank you. You have cleared that up for me. A Low Pressure engine start is normal.

Mark

Thanks for the clearup Lou :)