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A-10's APU
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Author:  cover72 [ 08 Dec 2010, 11:35 ]
Post subject:  A-10's APU
Hi, I'm writing a monograph on A-10 (something like this [google-translated to English]) and have some trouble getting exact information on it's systems. Right now, I've finished a chapter on APU. However, more than few questions which I couldn't answer by myself or available literature emerged during that work:
a) what is the maximal EGT (I mean, what is the EGT which forces APU control system to shut it down due to overheat?)
b) who is maker of the system - is it partly COST like Honeywell's GTP 36-155 on AH-64, or is it something proprietary, used only on A-10?
c) would somebody know the unit's (peak) power output in kW?
d) finally, searching for the exhaust and so on, I've learned that inlet is on the starboard side and exhaust is on the port side. However, some confusion breaks in:
d1: some sources claim that the cap on the exhaust is there to send hot exhaust gases away from the engine; others, however, claim it appeared in 1990's in order to protect the new, gray paint from soot. Which of those explanations would be true and why was the cap installed in 1990's, after 30 yrs of service?
d2: some hoby-modelers claim that APU inlet is the rectangular hole in the bottom aft fuselage - and others add there are more than just the two APU-related inlets/exhausts. Does anybody know if that's true and what are these?

I know it's lot of questions, but it'll really help me to get at least some of them answered. So thanks in advance for any help I'll get.
(And please excuse my English, I'm way more accustomed to reading than talking/writing)
Author:  jackb [ 09 Dec 2010, 09:45 ]
Post subject: 
If Dice, Lil Hilter or anyone else with better judgment than me says it's ok, I can answer all that (except d1) for you.
Author:  cover72 [ 09 Dec 2010, 11:48 ]
Post subject: 
Excelent; thanks a lot. I'm looking forward for their clearance.
Author:  Dice-man [ 09 Dec 2010, 19:08 ]
Post subject: 
I don't have a problem with all but a and c, they are a little in-depth and deal with the operation of the unit.
Author:  sgtgoose1 [ 12 Dec 2010, 16:03 ]
Post subject: 
I agree with you Dice,

Smith., Logan's, the Walk Around, TECH Book's all have the Information that is Out there on the A-10 even the APU.
Plus on Amazon there is a NEW on on the A-10C Conversion and gives what I can tell all the \"Need to know \" Info.

So there's plenty of stuff out there on the APU, and if it is Published
\"a\"
Then You don't need to know unless you plan on \"Cranking one Up\".

\"c\" how many KW's it puts out?' I never heard that question asked or saw that answer in any check list or in Engine Run School. I just turned them on or Fixed them which meant most of the time you Took them out , put a New one in , .

I guess we could Jerry rigged one back in the early Days of the
Gulf War to run an A/C unit with a Frig .? If we had enough KW's :wink: Why didn't one of you guys think of that? Almost 30 days without A/C was not fun, or something Cold
But the GroundPounders and Grunts had it worse then us


Goose
Author:  cover72 [ 13 Dec 2010, 13:19 ]
Post subject: 
sgtgoose1: thanks, but could you be more specific on the book title (as I understand your post, I believe it should be a single book?) Googling it up didn't bring up anything usable.
Also, I'm more interested in the \"hard info\" - as I am writing my own book (if I could call it that way), I don't want to rip off someone else's (because that would, to lesser or higher extent, happen if I searched for inspiration in books. After all, the first commercial book's author must have gotten his info on Hog somewhere else, too...). So I got myself the \"1A-10A-1\" manual and whatever I could get my hands on; still, it isn't as easy as SuperHornet, which has it's part numbers all around in aviation catalogs and on manufacturer's websites.

So, I'm mostly interested in clarifying the manual and generally/publicly available info, plus getting as much in-depth information as I legally could. And because that, I chose to only write about the \"A\" model, hoping that 30yrs old airframe (or at least it's general characteristics and systems) would be mostly un-classified... Is that wrong assumption?
And as an technician, wouldn't you happen to know the actual manufacturer of the APU?
Author:  jackb [ 14 Dec 2010, 05:38 ]
Post subject: 
a) denied
b) I won't be at work for a few weeks, so I can't look this up now, I can later though.
c) denied
d1) I couldn't tell you why, but I can tell you that it does not prevent the nacelle from getting soot stained. And \"as a safety shield in case of an APU exhaust shellout\" is not the reason either, it doesnt work, I've seen it happen. It appears to be a solution to a problem that doesn't exist.
d2) The rectangular hole in the bottom aft fuselage is the APU intake, that is, the air that is intook there is used for the combustion operation of the engine. The doghouse (the long rectangle on top of the aft fuselage between the nacelles is the ECS (enviromental) intake, and operates when the APU is running. There is also a small circle on the right side of the aft fuselage under the #2 eng and that is part of the ECS sys also. But the bigger rectangle on the bottom of the aft fuselage is the only APU intake.
Author:  Old Chief [ 14 Dec 2010, 14:34 ]
Post subject: 
Waking some very old brain cells, I believe the manufactuer of the APU is Garrett Airesearch. You probably won't find a lot of information about them because it's one of those companies that has acquired/been acquired/absorbed/spun off/re-sold to other aviation companies.

As I recall, the cap (deflector) was installed to protect the #1 lower engine door skin from heat damage. I don't know why that sticks in my mind but I believe it's accurate. It certainly isn't there to protect the paint because as JackB already stated, it doesn't work that way.

Are you looking for KW output of the turbine? You probably won't find an easy answer to that one. In the U.S., turbine output is usually expressed as thrust or horsepower, depending on the application of the turbine.

That's all I got...

OC
Author:  cover72 [ 14 Dec 2010, 14:46 ]
Post subject: 
Many thanks to the both of you, it really helped me.
Btw, OldChief - horsepowers could be easily converted*, as 1HP==0.745kW; I apologize for using European units :oops:

Would you guys mind if I asked some more questions in order to clarify stuff I just can't imagine from textual description?
____
*Google provides nice service for this, if you write 1 HP -> kW as a search query; it also converts currencies and other units that way
Author:  prkiii [ 14 Dec 2010, 14:48 ]
Post subject: 
jackb wrote:
a)
d1) I couldn't tell you why, but I can tell you that it does not prevent the nacelle from getting soot stained. And "as a safety shield in case of an APU exhaust shellout" is not the reason either, it doesnt work, I've seen it happen. It appears to be a solution to a problem that doesn't exist.


Old Chief wrote:
As I recall, the cap (deflector) was installed to protect the #1 lower engine door skin from heat damage. I don't know why that sticks in my mind but I believe it's accurate. It certainly isn't there to protect the paint because as JackB already stated, it doesn't work that way.
OC


When we started to install the deflectors in the mid 90s we were told it was mainly to prevent the staining of the nacella's but like you both said it doesn't work.
Author:  jackb [ 14 Dec 2010, 15:31 ]
Post subject: 
cover72 wrote:
Many thanks to the both of you, it really helped me.
Btw, OldChief - horsepowers could be easily converted*, as 1HP==0.745kW; I apologize for using European units :oops:

Would you guys mind if I asked some more questions in order to clarify stuff I just can't imagine from textual description?
____
*Google provides nice service for this, if you write 1 HP -> kW as a search query; it also converts currencies and other units that way

Ask away...
Author:  sgtgoose1 [ 14 Dec 2010, 21:13 ]
Post subject: 
What shield are you talking about?

Goose
Author:  Ice Pirate [ 14 Dec 2010, 21:36 ]
Post subject: 
Hey Goose, that was my question too. I think this pic will show the deflector well enough.
http://www.aircraftresourcecenter.com/A ... er/apu.jpg

The big problem with deflectors like this is that they really only work well with low velocity air or liquid flows. The APU is moving the hot exhaust way too fast for a partial deflector to have much effect.
Author:  cover72 [ 15 Dec 2010, 16:29 ]
Post subject: 
jackb wrote:
Ask away...

Thanks. It'll be about fuselage fuel tanks. The flight manual claims "Fuel tank sump drains are provided for each tank (...) Fuel cavity tanks are provided in each main tank, and protrude through the aircraft skin to give an indication of fuel cell leaks."
How should I visualize that? Right now, I understand this as if there was one metal container (fuel tank shown in cutaway diagrams; black on the original picture), on the bottom of this was "sump drain tank" (red; physically fragmented for each bladder cell) and above it there would be some rubberized "balloons/bubbles" (called "bladder cells" in manual) as the real main fuel tanks (green); fuel leaking/draining from bladder cells would flow to the bottom of the container, which would look like some kind of bathtub:
Image
But that sounds a bit crazy to me.. On the other side, as an IT technician I have fairly limited knowledge of fuel tanks and non-electronic components of any airframe - until I red 1A-10A-1, I thought fuel tanks are just those containers shown on cutaway diagrams.

And about that "protruding" fuel - that means there is some kind of glass pipe, through which it could be visually checked whether there is or is'nt fuel in the sump/cavity tank, or does the fuel just physically leak through the aircraft's surface?
Author:  jackb [ 15 Dec 2010, 17:41 ]
Post subject: 
Your original understanding was correct. There are 2 tanks in the center fuselage and 1 in each wing, for 4 total, like the cutaway shows. The tanks in the fuselage are each in a bladder, the ones in the wings is fuel directly behind the metal.

So... There is a SUMP drain for each tank, you could empty all fuel out of each tank by opening its respective SUMP drain.

The tanks in the fuselage are the only ones that have a CAVITY drain. If the bladder was leaking, it would fill up the fuselage if the drain wasn't there.

Imagine a water balloon in a box and the box has a small hole on the bottom. If the balloon (fuel tank) was leaking, how would you know from outside the box (the plane)? By seeing the water (fuel) leaking out the small hole in the bottom (the CAVITY drain).

I hope that's clear.
Author:  cover72 [ 15 Dec 2010, 18:24 ]
Post subject: 
I see. So the two fuselage tanks have sump tanks under them, into which you could release the fuel (remotely from the cockpit? Why would anyone do that?) and which serve as some kind of back-up for the case of \"fuel bladder\" leak. Is that normal on other aircraft as well, or is it Hog-specific redundancy? And if it's Hog-specific, what's the purpose of it? I mean, if the bladder was shot through beyond the possibilities of self-sealing rubber, wouldn't it be probable the sump tank would be shot through as well, given the direction of shooting would most probably come from underneath of the aircraft? That doesn't seem too redundant to me..

And about the cavity drain - wouldn't there be a real possibility the fuel will be dumped over board through it when the jet banks? Or are fuel losses during maneuvering due to cavity drains just so small they're ignorable?

Other than that, some aviation page claims following:
\"Even in the event of all four main tanks being penetrated and all contents lost, sufficient fuel is carried in two self-sealing sump tanks to allow flight for 230 miles (370 km)\" - I suppose that applies to the same two sump tanks described above, right?

Thanks for your answers.
Author:  sgtgoose1 [ 16 Dec 2010, 01:48 ]
Post subject: 
How did they come up with the \"230 miles\" on Shot out Tanks?

Goose
\"
Author:  cover72 [ 16 Dec 2010, 08:06 ]
Post subject: 
sgtgoose1 wrote:
How did they come up with the "230 miles" on Shot out Tanks?"

Well, sources for that claim appear to be Stephens World Air Power Journal, Spring 1994, p. 42 and Air International, June 1979, p. 270. But that apparently reckons with only fuel bladders being shot through, not the sump tanks.
Author:  sgtgoose1 [ 16 Dec 2010, 22:22 ]
Post subject: 
Ok,

Where's Pat? Which Hog flew 230 miles back with all the tanks shot out , and made it back home? I don't remember any fuel cells being replaced ?
I remember a Few wings being \"Shot to Hell, and 9186, Then the Cajun bird and a few others at KFIA, and You Guys at KKMC had a Couple Belly land and then the Crash due to BD.

I'd like to know which Jet did the 230 miles on sumps? I still find that :?
1 tank , maybe 2 , if it had that much damage he would have engine problems, or be battling the M/R.

She can take alot of Damage, and come home, we saw it first hand, but I want to know where these guys got there \"Facts\", and really in 1979?

Goose
Author:  Hawg166 [ 17 Dec 2010, 01:11 ]
Post subject: 
Wow, I'm outa practice, however........................the shield on the APU also came about in part because there had been instances with the turbine blade (the one you see when you look in the exhaust) failing and shooting out clear across the flightline. I remember reading the email. I believe it happened twice within weeks of each instance. The cap, while deflecting the exhaust, also would direct the blade directly to the ground in case of turbine failure.
Author:  Coach [ 17 Dec 2010, 04:30 ]
Post subject: 
I believe the reason for the APU deflector was to lower the possibility of post shutdown fire from residual fuel in the left engine when restarting the APU. Could be wrong...it also may have been purely cosmetic when they switched to the gray paint.

In other words...I don't know.

Coach
Author:  Weasel Keeper [ 18 Dec 2010, 08:06 ]
Post subject: 
Coach wrote:
I believe the reason for the APU deflector was to lower the possibility of post shutdown fire from residual fuel in the left engine when restarting the APU. Could be wrong...it also may have been purely cosmetic when they switched to the gray paint.

In other words...I don't know.

Coach


Not too sure how a small lip deflector would minimize post shut down fires. Not even sure the small deflector would shoot the APU guts to the ground if it grenaded. I'm sticking with the other explanations...to keep soot off the cowl/cosmetics. :) At Hill AFB when I launched one out Thursday in 0F weather, it didn't seem to deflect much of anything. I stood about 15 feet from it to keep warm and it seemed the exhaust hit me just fine to keep me warm as if it didn't even have a deflector. ;)
Author:  jackb [ 18 Dec 2010, 18:28 ]
Post subject: 
Weasel Keeper wrote:
Not too sure how a small lip deflector would minimize post shut down fires. Not even sure the small deflector would shoot the APU guts to the ground if it grenaded. I'm sticking with the other explanations...to keep soot off the cowl/cosmetics. :) At Hill AFB when I launched one out Thursday in 0F weather, it didn't seem to deflect much of anything. I stood about 15 feet from it to keep warm and it seemed the exhaust hit me just fine to keep me warm as if it didn't even have a deflector. ;)

Hawg166 wrote:
Wow, I'm outa practice, however........................the shield on the APU also came about in part because there had been instances with the turbine blade (the one you see when you look in the exhaust) failing and shooting out clear across the flightline. I remember reading the email. I believe it happened twice within weeks of each instance. The cap, while deflecting the exhaust, also would direct the blade directly to the ground in case of turbine failure.

I didn't realize that that was the intended role of the deflector, but it does work. I've seen it happen- an APU shelling out and the blade flying out, digging itself into the cement. I never thought about what it could do if it flew straight out unchecked until now.
Author:  jackb [ 18 Dec 2010, 19:05 ]
Post subject: 
cover72 wrote:
I see. So the two fuselage tanks have sump tanks under them, into which you could release the fuel (remotely from the cockpit? Why would anyone do that?) and which serve as some kind of back-up for the case of "fuel bladder" leak. Is that normal on other aircraft as well, or is it Hog-specific redundancy? And if it's Hog-specific, what's the purpose of it? I mean, if the bladder was shot through beyond the possibilities of self-sealing rubber, wouldn't it be probable the sump tank would be shot through as well, given the direction of shooting would most probably come from underneath of the aircraft? That doesn't seem too redundant to me..

And about the cavity drain - wouldn't there be a real possibility the fuel will be dumped over board through it when the jet banks? Or are fuel losses during maneuvering due to cavity drains just so small they're ignorable?

Other than that, some aviation page claims following:
"Even in the event of all four main tanks being penetrated and all contents lost, sufficient fuel is carried in two self-sealing sump tanks to allow flight for 230 miles (370 km)" - I suppose that applies to the same two sump tanks described above, right?

Thanks for your answers.

There is no sump TANK, just sump DRAIN. replace the word sump with tank and it's easier to understand.
The tanks are bladders, there is no opening for fuel to "spill out" of. If the bladder leaks, then the fuel comes out of the cavity drain. It does not leak under normal circumstances.
Author:  Weasel Keeper [ 18 Dec 2010, 19:45 ]
Post subject: 
jackb wrote:
Weasel Keeper wrote:
Not too sure how a small lip deflector would minimize post shut down fires. Not even sure the small deflector would shoot the APU guts to the ground if it grenaded. I'm sticking with the other explanations...to keep soot off the cowl/cosmetics. :) At Hill AFB when I launched one out Thursday in 0F weather, it didn't seem to deflect much of anything. I stood about 15 feet from it to keep warm and it seemed the exhaust hit me just fine to keep me warm as if it didn't even have a deflector. ;)

Hawg166 wrote:
Wow, I'm outa practice, however........................the shield on the APU also came about in part because there had been instances with the turbine blade (the one you see when you look in the exhaust) failing and shooting out clear across the flightline. I remember reading the email. I believe it happened twice within weeks of each instance. The cap, while deflecting the exhaust, also would direct the blade directly to the ground in case of turbine failure.

I didn't realize that that was the intended role of the deflector, but it does work. I've seen it happen- an APU shelling out and the blade flying out, digging itself into the cement. I never thought about what it could do if it flew straight out unchecked until now.


I'll take your word for it...and hope I never see it happen! ;)
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