effedia41
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Boeing KC-135R A/C Generators

Mon Feb 11, 2008 3:20 pm

Looking at the overhead panel of the KC-135R (with CFM-56 turbofan) I noticed that there are only three A/C generators. Which engine lacks it?
 
DeltaGuy
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RE: Boeing KC-135R A/C Generators

Mon Feb 11, 2008 3:31 pm

It's the #1 engine. The 707 has always had 3, and the #1 motor has always lacked that extra fairing. Take a look back at some old JT3 equipped frames, especially the FE panel, and you'll see it as well.

DeltaGuy
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Jetlagged
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RE: Boeing KC-135R A/C Generators

Mon Feb 11, 2008 7:53 pm



Quoting DeltaGuy (Reply 1):
It's the #1 engine. The 707 has always had 3, and the #1 motor has always lacked that extra fairing. Take a look back at some old JT3 equipped frames, especially the FE panel, and you'll see it as well.

I think the question maybe referring to AC electrical generators rather than air conditioning turbo-compressors. From the way the panel is laid out, most likely the answer is the same though (engine 1).
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boeingfixer
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RE: Boeing KC-135R A/C Generators

Mon Feb 11, 2008 10:39 pm



Quoting DeltaGuy (Reply 1):
It's the #1 engine. The 707 has always had 3, and the #1 motor has always lacked that extra fairing. Take a look back at some old JT3 equipped frames, especially the FE panel, and you'll see it as well.

DeltaGuy

Actually, the B707 always had 4 AC Generators. Generator control panel at top left has controls for 4 AC generators


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Also remember that the KC-135 and B707 are very different aircraft. The KC-135 has more in common with the Boeing Dash 80 than the B707.

As for only three AC generators on the KC-135, I can only guess that the power consumption is less on the KC-135 than the B707(galleys etc...) and thus it only requires 3 generators.

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John
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ex52tech
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RE: Boeing KC-135R A/C Generators

Wed Feb 13, 2008 4:25 am

Ahhh....... the KC135A did not have a generator on #4 engine. So my guess is that they would have had to accomplish a major modification of the electrical system on the R model to have more than three, and with the removal of the water injection system, there would be less demand on the electrical system. As far as I know all of the R models are converted A models.

Quoting DeltaGuy (Reply 1):
It's the #1 engine. The 707 has always had 3, and the #1 motor has always lacked that extra fairing.

I wonder if you are thinking about the turbo compressor inlets on the pylon above the engine inlet. If that is what you are talking about, remember that some of the 720s had only two turbo compressors on the #2 and #3 engines.
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DeltaGuy
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RE: Boeing KC-135R A/C Generators

Wed Feb 13, 2008 9:56 pm



Quoting Ex52tech (Reply 4):
I wonder if you are thinking about the turbo compressor inlets on the pylon above the engine inlet. If that is what you are talking about, remember that some of the 720s had only two turbo compressors on the #2 and #3 engines.

That was it!! It's been a long time since I jumpseated on that Omega Tanker, but I did remember seeing how there was only 3 of certain things...only 3 TR's as well.

Good thread! This is the kind of tech/ops questions that we need more of!

DeltaGuy
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ex52tech
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RE: Boeing KC-135R A/C Generators

Fri Feb 15, 2008 3:08 am

Another little bit of trivia.....The KC135A did not have turbo compressors at all. The aircraft employed freon airconditioning pacs..

All that smoke in water injection, and all the holes in the ozone.  Wow!
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Moose135
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RE: Boeing KC-135R A/C Generators

Sun Feb 17, 2008 9:09 pm

All this talk about AC generators got me to thinking...the A-model had another generator, powered by a pump on the right-hand hydraulic system, that powered the copilot's flight instruments. I got out just as the R-models were coming on board and never got to fly them, but I'm assuming was this retained with the R-model conversion. Am I correct in that assumption?
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rsbj
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RE: Boeing KC-135R A/C Generators

Thu Feb 21, 2008 4:21 am

Not just the R's retained the Co-pilot

Quoting Moose135 (Reply 7):
All this talk about AC generators got me to thinking...the A-model had another generator, powered by a pump on the right-hand hydraulic system, that powered the copilot's flight instruments. I got out just as the R-models were coming on board and never got to fly them, but I'm assuming was this retained with the R-model conversion. Am I correct in that assumption?

Yes, the R model has it. Also, our E model's had this neat, and very redundant, feature.
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Venus6971
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RE: Boeing KC-135R A/C Generators

Fri Feb 22, 2008 3:43 pm



Quoting Ex52tech (Reply 6):
Another little bit of trivia.....The KC135A did not have turbo compressors at all. The aircraft employed freon air conditioning packs..

The KC-135 uses bleed air or ram air for air conditioning, if you notice the ac pack is in the left keel beam, the USAF had some C-18's which were old American Airline 707-320s that used freon packs since these initially bought from Boeing for short haul routes and needed something to cool the acft down quick, in a KC-135 you are either freezing or roasting, there was temp controller in the cabin on the fwd bulkhead near the lavatory which I think was there just for looks. Also the C-18's only had 2 turbo-compressors which is the AA ordered them, the TC's gave you clean air to pressurize the cabin instead of using bleed air which sometimes gave the cabin an oily smell if you also had nose cowl anti ice turned on and the seal on the #1 bearing seal leaked especially on the TF-33(Jt-3D)
I remember coming back from Greenville Texas in my C-137B(707-153B) dead heading to ADW we had it up at 41,000 ft and had to supplement the TC's with engine bleed air to keep the acft pressurized at 8.6 psi due to the thin air. Plus also to insure the pax o2 masks would not drop.
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Viscount724
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RE: Boeing KC-135R A/C Generators

Fri Feb 22, 2008 11:28 pm



Quoting Ex52tech (Reply 4):
Quoting DeltaGuy (Reply 1):
It's the #1 engine. The 707 has always had 3, and the #1 motor has always lacked that extra fairing.

I wonder if you are thinking about the turbo compressor inlets on the pylon above the engine inlet. If that is what you are talking about, remember that some of the 720s had only two turbo compressors on the #2 and #3 engines.

Not all 707s had 3 turbocompressors. AA's (both -123/-123B and -323B/C) only had 2 turbocompressors on engines 2 and 3, like the 720/720B. Note the narrow engine pylon on #4 in photos below (same as #1). I recall reading that AA decided they only needed 2 since their routes were domestic only when they ordered their 707s and they would never be far from an alternate airport in the event of a pressurization failure.


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If memory correct a few other 707s, including Air India's early R-R Conway-powered 707-420s, also only had 2 turbocompressors although you can't see that visually on the AI -420s since their pylons are the same for all engines (as on JT3C and JT4A 707s), unlike those on JT3D-powered 707s (and 720s) where the pylons on engines without turbocompressors are much .
 
Venus6971
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RE: Boeing KC-135R A/C Generators

Sat Feb 23, 2008 1:05 am



Quoting Viscount724 (Reply 10):
Not all 707s had 3 turbocompressors. AA's (both -123/-123B and -323B/C) only had 2 turbocompressors on engines 2 and 3, like the 720/720B. Note the narrow engine pylon on #4 in photos below (same as #1). I recall reading that AA decided they only needed 2 since their routes were domestic only when they ordered their 707s and they would never be far from an alternate airport in the event of a pressurization failure.

in the event of a TC failure it you could select bleed air tto pressurize
I would help you but it is not in the contract
 
ex52tech
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RE: Boeing KC-135R A/C Generators

Sat Feb 23, 2008 3:56 am



Quoting Venus6971 (Reply 9):
clean air to pressurize the cabin instead of using bleed air which sometimes gave the cabin an oily smell if you also had nose cowl anti ice turned on and the seal on the #1 bearing seal leaked especially on the TF-33(Jt-3D)

The oily smell with anti-ice on with the J-57, and the TF-33, was because the hydraulic resevoirs were pressurized by a line that fed off the anti-ice duct. When the check valve stuck open in that line hydraulic fluid would drain back into that anti-ice duct, turn on the anti-ice and you got smoke or oily smell in the airplane.

I was standing just off of the inlet of a J57-59W one morning, a little closer than I should have been, the inlet was icing, and I told the guy running the engines to snap on the anti-ice. The engine injested a large quantity of hydraulic fluid that was in the duct. The engine had a massive compressor stall, which sent me heading for the hills, we figured that the fluid probably ignited in the compressor before it even got to the combustion chamber.

The J-57 was known for breathing anyway, and they would loose oil past the bearing carbon seals and smoke the cabin, so that was another way to get the oily smell in the cabin.
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