Reggaebird
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747SP Cabin Window Question

Tue Sep 20, 2011 4:59 pm

Check out the view at 1:01 in the following video of a Boeing 747SP. Does anyone know why there are rectangular protrusions around the windows?

http://www.youtube.com/watch?v=jnl0M0AthNA&feature=channel_video_title
 
KDTWflyer
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Joined: Tue Jun 29, 2004 12:51 pm

RE: 747SP Cabin Window Question

Tue Sep 20, 2011 6:42 pm

NW B744 B742 B753 B752 A333 A332 A320 A319 DC10 DC9 ARJ CRJ S340
 
KDTWflyer
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RE: 747SP Cabin Window Question

Tue Sep 20, 2011 6:46 pm

NW B744 B742 B753 B752 A333 A332 A320 A319 DC10 DC9 ARJ CRJ S340
 
LTC8K6
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RE: 747SP Cabin Window Question

Tue Sep 20, 2011 6:52 pm

Looks like a lot of structural patching...
 
Viscount724
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RE: 747SP Cabin Window Question

Tue Sep 20, 2011 9:42 pm

Quoting LTC8K6 (Reply 3):
Looks like a lot of structural patching...

It's common on many older aircraft to overcome "aging" issues related to fatigue, cracking etc. Enlarge the photo below and note all the "doubler" patches on the 25-year-old WN 733 below, including a large one above the windows starting just behind the first window, many smaller ones below the windows and in other places, including a large one around the upper left hand corner of the door.


View Large View Medium
Click here for bigger photo!

Photo © Suresh A. Atapattu

 
KELPkid
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RE: 747SP Cabin Window Question

Tue Sep 20, 2011 9:56 pm

Quoting Viscount724 (Reply 4):
It's common on many older aircraft to overcome "aging" issues related to fatigue, cracking etc. Enlarge the photo below and note all the "doubler" patches on the 25-year-old WN 733 below, including a large one above the windows starting just behind the first window, many smaller ones below the windows and in other places, including a large one around the upper left hand corner of the door.

The canyon blue paint has a way of making that so much more obvious...You used to have to be looking for the doublers when the paint was still brownish tan  
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HAWK21M
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RE: 747SP Cabin Window Question

Wed Sep 21, 2011 11:20 am

Seems to be doublers post structural repair ......maybe recommended by the Manufacturer or a repair carried out.Maybe someone having worked on the type would know in more detail.
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474218
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RE: 747SP Cabin Window Question

Thu Sep 22, 2011 3:28 am

The WN photo shows how the "lap joints" were reinforced (long rectangle doublers above and below the windows). The installation of these reinforcement doublers was the result of the Aging Aircraft Task Force recommendations after the Aloha incident. All 737's that have reached a specified number of flight cycles require these doublers.

However, there are also numerous repairs scattered about (the smaller square and rectangle doublers). These patches would have been installed to repair ramp damage, in service cracking and or corrosion.
 
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HAWK21M
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RE: 747SP Cabin Window Question

Fri Sep 23, 2011 11:55 am

These Patches in the Frontal areas of the fuselage would contribute to significant payload restrictions due performance penalties.
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tdscanuck
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RE: 747SP Cabin Window Question

Fri Sep 23, 2011 1:30 pm

Quoting HAWK21M (Reply 8):

These Patches in the Frontal areas of the fuselage would contribute to significant payload restrictions due performance penalties.

Is that a documented thing? Beyond the weight, those patches are so thin that I doubt they're even penetrating the boundary layer once you get a few frames back.

Tom.
 
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HAWK21M
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RE: 747SP Cabin Window Question

Sun Sep 25, 2011 12:19 pm

Quoting tdscanuck (Reply 9):

Is that a documented thing? Beyond the weight, those patches are so thin that I doubt they're even penetrating the boundary layer once you get a few frames back.

I'm sure these patches on Section 41 frontal area would contribute significantly to drag & loss of aerodynamic efficiency & subsequent ROC.
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