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Topic: Tech Question On The DC-8
Username: Vertigo
Posted 2002-06-13 07:31:48 and read 2930 times.

Hi, all.
I work for UPS at their DIA facility.

Two nights ago I was marshaling our DC-8 out and was about to give the all clear signal when two puffs of steam or pressurized air shot out from the right side of the fuselage just behind the cockpit. What is this? Does it have something to do with checking the pressurization of the fuselage before Takeoff? The odd thing is this is only the second time I've seen this and I marshal every night.

Thanks in advance

Topic: RE: Tech Question On The DC-8
Username: JETPILOT
Posted 2002-06-13 11:16:47 and read 2902 times.

I would have said they were the turbocompressors being tested, but UPS only has 70's and the TC's were removed. Was it subcontractor's plane or one of yours?

Were the engines running, or you were going to give the all clear to start?

JET

Topic: RE: Tech Question On The DC-8
Username: TechRep
Posted 2002-06-13 13:07:42 and read 2895 times.

I think your mistaken about where the origination of the puff came from, The puff of "steam" was the testing of the window bleed air. A handle located on the Capt's left above the briefcase area and F/O's right above the briefcase area can be locked in the on position and is loaded to the closed position. In cold or humid conditions this will look like a huge puff of steam that shoots back and sometimes depending on your position will appear to originate behind the windows.

This system is tied directly into the Main Bleed Line that extends below the "tunnel" and feed from the engines or ground pneumatic sources. Depending on the After Start checklist at UPS this may not have to be checked. If it is part of the checklist the reason why you never seen it tested is easy to explain. Crew members will only crack the valve and not turn it all the way, essentially testing the system but you will not get the puff.

TechRep
http://www.imageevent.com/techrep

Topic: RE: Tech Question On The DC-8
Username: Vertigo
Posted 2002-06-13 19:13:14 and read 2870 times.

I think TechRep answered my question JetPilot but thanks anyway.

If it still helps this was a Dc-8 73. N808UP to be exact. This occurred after all four engines were running and the plane was about to begin moving to the taxiway.

Just one more question TechRep. Is this handle visible in any of the following pictures? I visit the cockpit frequently and would be interested in where it is located.


View Large View Medium
Click here for bigger photo!

Photo © Erik Frikke



View Large View Medium
Click here for bigger photo!

Photo © Mike Bates



View Large View Medium
Click here for bigger photo!

Photo © Robert Hockemeijer

Topic: RE: Tech Question On The DC-8
Username: TechRep
Posted 2002-06-13 19:36:33 and read 2863 times.

It is under the sliding side windows and next to the foward display console tucked away in the corner. It is not displayed in any of the above photos.

TechRep

Topic: RE: Tech Question On The DC-8
Username: TechRep
Posted 2002-06-13 20:07:29 and read 2859 times.

You can see the handle displayed in this picture. It is located in front of the steering tiller, it has a little white ball attached to it.



TechRep

Topic: RE: Tech Question On The DC-8
Username: 737doctor
Posted 2002-06-13 23:27:19 and read 2836 times.

I spent 6+ years working on the DC-8 and I'm gonna have to agree with TechRep here. Sounds like window bleed air to me also.

Topic: RE: Tech Question On The DC-8
Username: TechRep
Posted 2002-06-15 13:19:17 and read 2781 times.

Any other DC-8 questions?

TechRep

Topic: RE: Tech Question On The DC-8
Username: Douglas DC 8
Posted 2002-06-15 16:35:20 and read 2774 times.

Yes, I had a question TechRep.
What exactly made the DC 8 technically better than the B707 in the early jet age or even today? I know f. e. the better turning radius because the two rear wheels of each bogie can be put in a free swiveling mode to assist in making sharp turns on the ground.

Topic: RE: Tech Question On The DC-8
Username: TechRep
Posted 2002-06-16 13:20:33 and read 2739 times.

As far as being technically better that's a tough one. They are both in the 40 Ton bracket with almost identical performance. I like the DC-8 there is no mystery and have written much about this previously, specifically why the DC-8 is the better aircraft. The B707 sold more than the DC-8 for sure but the winner is now ICAO Stage 3 compliant on a larger scale and the other not.

I worked both aircraft side by side in heavy check in the early 90's at Batch/Greenwich Air Services. I found the B707 much more prone to corrosion and the sub-frame, ribs, stringers, intercostals and floor supports were of like materials but thinner. Boeing products do not include floor boards as Primary Structure Items where Douglas products seemed to, there is a slight plus for the Boeing there.

I believe all aircraft should be rated by quality by what's underneath. As stated before Boeing does not support old aircraft they are in the business to sell new aircraft, where Douglas would. The commitment of Douglas to support it's older frames was the reason why the DC-8 was the winner.

TechRep

Topic: RE: Tech Question On The DC-8
Username: 737doctor
Posted 2002-06-17 01:59:20 and read 2712 times.

Once again, I concur with TechRep. While the 707 may have been more successful in its heyday, the DC-8 has proved itself to be superior by virtue of its construction. Those planes are built like tanks. When the airlines quit flying them after years of faithful service, the cargo airlines cut a hole in the side of them and have been flying the crap out of them ever since.


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