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sdwranglers
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Removal Of Windows On Freighter Conversions

Thu Mar 30, 2006 2:37 am

I've been wondering why it is that when a former passenger a/c is converted to a freighter, the windows are often removed and "filled in" with "skin". Is it a weight factor and if so, do those windows really weigh enough to make a difference? It wouldn't seem that leaving the windows in place would pose a safety risk since everything in a freighter is on rollers, tracks and locked in place. I'm sure there is a reason since it is done,I searched the site for an answer, but was unable to find any thing relating specifically to my question.
 
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Starlionblue
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RE: Removal Of Windows On Freighter Conversions

Thu Mar 30, 2006 2:47 am

It's not so much weight as maintenance. Windows sometimes crack and must be periodically checked. A bolted on aluminum plate will pretty much last as long as the skin around it.

Also, if you want to revert back, it's not that hard to install windows again.

Incidentally, most of the early 747-100s and -200s had 10 window holes per side on the upper deck, but many had only 3 windows. The rest were plates.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
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HAWK21M
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RE: Removal Of Windows On Freighter Conversions

Thu Mar 30, 2006 2:51 am

The Plugs can withstand more Environmental induced damage compared to Windows.
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
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litz
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RE: Removal Of Windows On Freighter Conversions

Thu Mar 30, 2006 6:57 am

Is there a weight difference between a window plug and a normal window?

I would think the metal would be far lighter for the same strength ...

(multiplied down both sides of a larger airliner, I imagine that could add up quick)

- litz
 
greasespot
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RE: Removal Of Windows On Freighter Conversions

Thu Mar 30, 2006 10:50 am

Actually the metal plugs, that i have come accross on the B727, Weigh more than the plastic windows....I was suprised and how beefy they were.

GS
Sometimes all you can do is look them in the eye and ask " how much did your mom drink when she was pregnant with you?"
 
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HAWK21M
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RE: Removal Of Windows On Freighter Conversions

Fri Mar 31, 2006 12:35 am

And to Mention....Three panes [2panes + 1 plastic liner] replaced by One plug.
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
broke
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RE: Removal Of Windows On Freighter Conversions

Fri Mar 31, 2006 4:23 am

The main reason for replacing the acrylic window panes with metal plugs is the cost of maintenance. Even if the acrylic window pane is painted, it will deterioriate due to the sun's ultraviolet light and exposure to air pollution. You will get cracks where the window fits into the fuselage and crazing in the window pane which can also develop into cracks.
There have been Airworthiness Directives (AD's) against window panes, while I don't know of any against the metal plugs.
 
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HAWK21M
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RE: Removal Of Windows On Freighter Conversions

Wed Apr 12, 2006 9:48 pm

Quoting Broke (Reply 6):
There have been Airworthiness Directives (AD's) against window panes, while I don't know of any against the metal plugs

Are there any removal checks on these ever.
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
SkydrolBoy
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RE: Removal Of Windows On Freighter Conversions

Thu Apr 13, 2006 12:40 am

Last year there was an AD that came out (at least i think it was an AD), that required us to pull all the windows in our 727-100F's and replace them with plugs. The plugs we installed weighed a little more than the windows we pulled out. On our 727-200F's the windows are replaced with a different style plug that requires you to drill the window frame to install it, Once you have put this stle plug in you can never go back to a window with out replacing the window frame aswell. These plugs are actually fairly light compared to the window.
 
FredT
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RE: Removal Of Windows On Freighter Conversions

Thu Apr 13, 2006 3:07 am

Quoting Litz (Reply 3):
Is there a weight difference between a window plug and a normal window?

Our plugs are 100-200 grams lighter than the windows they replace. A bit more if the windows have a third inner pane. They could be cheaper if they were heavier, I'd say, so I'm not surprised that there are other plugs which are indeed heavier than the windows.

As for things being strapped down in place in cargo aircraft, that may be true when taking off but not while loading them. Cargo aircraft interiors take a beating, and not having to worry about windows is nice.

Cheers,
Fred
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Ferret
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RE: Removal Of Windows On Freighter Conversions

Mon Jun 11, 2007 10:35 am

So this is an old topic, but I'm hoping my post gets it some attention...I had been wondering about this topic myself and was glad to see someone had asked and it had been so well answered.

A follow-on question: When the plugs are installed, are all the panes removed or just covered? Or does it vary?
Thanks in advance!  Smile
Murphy lives here.
 
Buzz
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RE: Removal Of Windows On Freighter Conversions

Mon Jun 11, 2007 11:35 am

Hi Ferret, Buzz here. The acrylic window panes are removed. The inner and outer sort of come out as a set, held in place by a rubber seal. The 3rd inner pane is a non-structural part of the cabin sidewall to keep little kids from drawing on them with crayons (grin).
So it's all removed and a piece of aluminum takes the place.

g'day
 
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HAWK21M
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RE: Removal Of Windows On Freighter Conversions

Mon Jun 11, 2007 4:35 pm

Quoting Ferret (Reply 10):
When the plugs are installed, are all the panes removed or just covered

The Windows are normally middle & outer pane held by a seal & an Acrylic Plastic window on the inside which is only decorative.On the Freighters the Inner is not present & the Outer & Middle pane set is replaced by a Metal plug,which like the panes are held by clips screwed into the surrounding frame area.
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
N231YE
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RE: Removal Of Windows On Freighter Conversions

Mon Jun 11, 2007 7:39 pm

Quoting SDWranglers (Thread starter):
the windows are often removed and "filled in" with "skin".



Quoting Buzz (Reply 11):



Quoting HAWK21M (Reply 12):

I recall that the windows are not removed, but "plugged." (?) With TWA Flight 800, the upper deck fell on its side against the water, thus knocking out all of the plugs (TWA's last 2 747-100s came with the later-standardized 10 windows on the upper deck, while TWA tried to keep the fleet uniform with its older 747s, and plugged up all but 3).
 
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HAWK21M
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RE: Removal Of Windows On Freighter Conversions

Mon Jun 11, 2007 8:03 pm

Quoting N231YE (Reply 13):
I recall that the windows are not removed, but "plugged."

Freighters conversions either Metal Plug or retain the Windows.I don't get your sentence.
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
aeroweanie
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RE: Removal Of Windows On Freighter Conversions

Mon Jun 11, 2007 11:12 pm

Quoting Litz (Reply 3):
Is there a weight difference between a window plug and a normal window?

The plugs are lighter - over 500 lbs for a 747-400. For more info see Liteair's website: http://www.liteair.com/
 
Ferret
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RE: Removal Of Windows On Freighter Conversions

Tue Jun 12, 2007 4:36 am

Quoting AeroWeanie (Reply 15):
The plugs are lighter - over 500 lbs for a 747-400

I assume by this statement, you mean that the OVERALL weight savings is 500 pounds. Otherwise, those are some heavy windows!!!!  duck 
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N231YE
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RE: Removal Of Windows On Freighter Conversions

Tue Jun 12, 2007 5:49 am

Quoting HAWK21M (Reply 14):
Freighters conversions either Metal Plug or retain the Windows.I don't get your sentence.

I was talking about leaving the windows in-place, with a metal plug being mounted on top. Maybe the window is totally removed with Freighter conversions, and the window left in place on passenger variants in the advent of an aircraft sale to an operator that want the aircraft (and aircraft window use) configured differently...I don't know.
 
aeroweanie
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RE: Removal Of Windows On Freighter Conversions

Tue Jun 12, 2007 8:59 am

Quoting N231YE (Reply 17):
I was talking about leaving the windows in-place, with a metal plug being mounted on top. Maybe the window is totally removed with Freighter conversions, and the window left in place on passenger variants in the advent of an aircraft sale to an operator that want the aircraft (and aircraft window use) configured differently...I don't know.

Look at the Liteair website - the transparencies and their frames are removed completely.
 
N231YE
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RE: Removal Of Windows On Freighter Conversions

Tue Jun 12, 2007 9:24 am

Quoting AeroWeanie (Reply 18):
Look at the Liteair website - the transparencies and their frames are removed completely.

Thanks, for whatever reason, I was always under the impression that the windows are simply "covered over," but as I see now, that is not the case.
 
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nonfirm
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RE: Removal Of Windows On Freighter Conversions

Tue Jun 12, 2007 9:34 am

They are removed for maintenance because the sidewalls in the aircraft are replaced with solid liner panels.There is no access to them.Atleast on our freighter but a different story on our combi's.  airplane 
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LTU932
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RE: Removal Of Windows On Freighter Conversions

Tue Jun 12, 2007 10:40 am

Quoting Starlionblue (Reply 1):
Incidentally, most of the early 747-100s and -200s had 10 window holes per side on the upper deck, but many had only 3 windows. The rest were plates.

I believe that's not because windows were plugged, but because the structure allowed for only three upper deck windows per side on the early 747s. To convert those 747s to the 10 per side upper deck window configuration, you'd have to cut the upper deck section with the windows out and install the new one.

View Large View Medium
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Photo © AirNikon
View Large View Medium
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Photo © Frank C. Duarte Jr.

Notice that in the second picture, the section with the upper deck windows has aged differently than the rest of the fuselage. This shows that in order to increase the amount of windows in the upper deck from 6 to 20 (from three to ten on each side respectively), you'd need heavier structural modifications.

[Edited 2007-06-12 03:41:59]
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Starlionblue
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RE: Removal Of Windows On Freighter Conversions

Tue Jun 12, 2007 11:30 am

Quoting LTU932 (Reply 21):
I believe that's not because windows were plugged, but because the structure allowed for only three upper deck windows per side on the early 747s. To convert those 747s to the 10 per side upper deck window configuration, you'd have to cut the upper deck section with the windows out and install the new one.

Good clarification. My (muddled) point was that many believe the -100 only had the "3 window" look. In fact, Boeing went to 10 during the -100 production run but many operators kept 3 windows despite the holes being there.

[Edited 2007-06-12 04:31:03]
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
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LTU932
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RE: Removal Of Windows On Freighter Conversions

Tue Jun 12, 2007 12:54 pm

Quoting Starlionblue (Reply 22):
Good clarification. My (muddled) point was that many believe the -100 only had the "3 window" look. In fact, Boeing went to 10 during the -100 production run but many operators kept 3 windows despite the holes being there.

That must have probably happened some time after the 10 window option was launched. The two 747s in the picture I linked were early built aircraft (line number 62 and 40 respectively), so this leads me to the question of when exactly the 10 window per side upper deck was introduced? I guess it wasn't immediately launched when Boeing was completing the prototype 747-200B aircraft in this picture.

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L-188
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RE: Removal Of Windows On Freighter Conversions

Tue Jun 12, 2007 1:05 pm

Quoting LTU932 (Reply 21):
believe that's not because windows were plugged, but because the structure allowed for only three upper deck windows per side on the early 747s.

The early aircraft where built with 3 windows, this was the age where the "Bump" was intended to be a bar/lounge area for the passengers. But economics pretty much killed that use off fairly quickly. In order to add passenger seats to the upstairs area the windows where added.

But back in the seventies since airlines where still concerned about appearances a number of airlines had Boeing plug seven of the windows off so that all of their originally configured 747's and latter 10 window aircraft look the same.
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Starlionblue
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RE: Removal Of Windows On Freighter Conversions

Tue Jun 12, 2007 9:14 pm

Quoting LTU932 (Reply 23):
so this leads me to the question of when exactly the 10 window per side upper deck was introduced? I guess it wasn't immediately launched when Boeing was completing the prototype 747-200B aircraft in this picture.

Indeed. Some of the -200s also had 3 windows.

According to "Boeing 747 - Design and Development since 1969" by Norris & Wagner, the 10 windows came about during -200B production. Only the first few -200Bs had 3 windows. There is scant information on the subject.

However, production times for the -100 and the -200 do overlap. And I could swear I've read that there are -100s out there with 10 windows.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
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HAWK21M
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RE: Removal Of Windows On Freighter Conversions

Tue Jun 12, 2007 9:58 pm

Quoting N231YE (Reply 17):
I was talking about leaving the windows in-place, with a metal plug being mounted on top

Won't fit & if modified to accomodate both why add weight.
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
N231YE
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RE: Removal Of Windows On Freighter Conversions

Tue Jun 12, 2007 11:18 pm

Quoting LTU932 (Reply 23):
so this leads me to the question of when exactly the 10 window per side upper deck was introduced?

The 10 upper-deck windows option became available on the -200B (starting with the 7th airframe) in July, 1971.

I don't know when this option became standard on the 747-100, but as I stated earlier, TWA 800 (N93119) was the second-last 747 to be delivered to TWA, in October, 1971. Both the last two aircraft came with the 10 window-standard, but to keep uniformity with the rest of the fleet (that had only 3 windows), TWA plugged up the other 7 windows on those 2 frames. So possibly after the option was introduced, Boeing quickly made it standard...
 
iRISH251
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RE: Removal Of Windows On Freighter Conversions

Fri Jun 15, 2007 3:26 am

Saudia and Iran Air 747-100s were built with the ten windows, as they were ordered after the -200 was already in production.

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