SXDFC
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737 Landing Light Question(s)

Tue Feb 10, 2009 2:25 am

Hey Guys:

I noticed in many pictures of the Boeing 737 and after flying on one several times, that the landing lights on the Boeing 737-100-500 have their landing lights on the flap canoe, and on the 737-600-900ER have the landing lights on the bottom of the fuselage. My question is why did Boeing opt to put them lower on the 73NG series as opposed to the flap canoe?

Also this is on a bit of a side note, but what dictates where to put these landing lights? I know on the Airbus A32S there located near the landing gear, and on some of the 707 models, there located between the two engines as well.

73NG:


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Photo © D. Raemaekers



Classic:


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ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.
 
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HAWK21M
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RE: 737 Landing Light Question(s)

Tue Feb 10, 2009 7:55 am

The classic retractable Landing light on the Outboard Flap Canoe used to suffer from a drag penalty if the motor jammed & the light could not be retracted flush.
However the below fuselage location of landing lights on the -NGs suffered from FOD & water sray damage leading to cracking.

regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
chrisMUC
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RE: 737 Landing Light Question(s)

Tue Feb 10, 2009 12:33 pm

Hi,
what you're talking about is the second pair of landing lights, on the classics they're called outboard, don't know about the NGs. Both version do also have landing lights at the roots of the wings.
At my company we use the outboard landing lights only if an inboard one is inop, since there can occur some problems with the wiring of the outboard ones and they're not a big help any ways (much darker than the inboard ones).
According to the MEL, one landing light on each side may be inop, but not both inboard landing lights at the same time.
The mechanism of the outboard landing lights on the classics is quite complicated since they are changing their angle of extension according to flap movement, that might be one reason why boeing changed their position.

[Edited 2009-02-10 04:34:56]
 
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HAWK21M
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RE: 737 Landing Light Question(s)

Tue Feb 10, 2009 2:49 pm



Quoting ChrisMUC (Reply 2):
At my company we use the outboard landing lights only if an inboard one is inop, since there can occur some problems with the wiring of the outboard ones and they're not a big help any ways (much darker than the inboard ones).

Is that your company SOP or only an MEL requirement.....I would think the latter,under normal circumstances all Landing lights should be functioning.
regds
MEL...
I may not win often, but I damn well never lose!!! ;)
 
chrisMUC
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RE: 737 Landing Light Question(s)

Tue Feb 10, 2009 9:46 pm

they are functioning, but we don't switch them on according to our company SOP.
We only use them if an inboard light is u/s (usually not for more than one flight, then the inop inboard one will be fixed).
 
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HAWK21M
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RE: 737 Landing Light Question(s)

Wed Feb 11, 2009 7:47 am



Quoting ChrisMUC (Reply 4):

they are functioning, but we don't switch them on according to our company SOP.

Interesting.....Is the regulatory authority ok with this SOP.
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
chrisMUC
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RE: 737 Landing Light Question(s)

Wed Feb 11, 2009 10:57 am



Quoting HAWK21M (Reply 5):
Is the regulatory authority ok with this SOP.

Of course!

You really don't need the outboard landing lights for safe operation, the inboard landing lights are so much brighter that standing on the rwy you can hardly recognize whether the outboard landing lights are on or off.
Reason for the change of our SOP was, that in a few cases it happened that when the outboard landing lights were switched on, an engine stopped. I'm not sure if I recall correctly, but I think to remember that it had something to do with the wiring of the lights and the fuel shut off valves.
There is a Boeing modification kit, but we don't have it installed.
 
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Starlionblue
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RE: 737 Landing Light Question(s)

Wed Feb 11, 2009 12:19 pm



Quoting ChrisMUC (Reply 6):
Reason for the change of our SOP was, that in a few cases it happened that when the outboard landing lights were switched on, an engine stopped.

 rotfl  I need to recount this one to my friend who is afraid of flying. To think I keep prattling on about redundancy and all that.
"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: 737 Landing Light Question(s)

Wed Feb 11, 2009 12:54 pm



Quoting ChrisMUC (Reply 6):
Reason for the change of our SOP was, that in a few cases it happened that when the outboard landing lights were switched on, an engine stopped. I'm not sure if I recall correctly, but I think to remember that it had something to do with the wiring of the lights and the fuel shut off valves.

This is news....any details,if it occured frequently,Boeing would have commented on it.Its a serious short,if thats what caused this.
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
wilco737
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RE: 737 Landing Light Question(s)

Wed Feb 11, 2009 12:58 pm



Quoting HAWK21M (Reply 8):
This is news....any details,if it occured frequently,Boeing would have commented on it.Its a serious short,if thats what caused this.

This is no news. This is older than 2 years. And from what I heard it only happened once and just as a precaution it is recommended not to use the outboard landing lights.
But I still see many airlines using them, so it doesn't seem to be too serious.

wilco737
 
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HAWK21M
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RE: 737 Landing Light Question(s)

Wed Feb 11, 2009 8:10 pm



Quoting WILCO737 (Reply 9):
This is no news. This is older than 2 years.

Is there an SB to this effect?
regds
MEL...
I may not win often, but I damn well never lose!!! ;)
 
wilco737
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RE: 737 Landing Light Question(s)

Wed Feb 11, 2009 9:08 pm



Quoting HAWK21M (Reply 10):
Is there an SB to this effect?

I don't know. I am not on the 737 anymore for nearly 2 years now.

wilco737
 
AA737-823
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RE: 737 Landing Light Question(s)

Fri Feb 13, 2009 12:27 pm

I am on the 737 (though as a tech, not a cap'n), and I am not aware of ANY relationship between landing lights coming on and engines going off.
My company uses all available lighting, for increased visibility and hence safety.

The mechanism by which the classic ones are adjusted during flap transit isn't as complicated as you think. There's a linkage arm that connects the light assembly to a stationary portion of the wing, and as the canoe moves downward, the arm adjusts the angle of the lamp upward, resulting in a more-or-less zero net affect.

The ones on the NG are much larger in size, higher in wattage, and more prone to runway debris damage.
In the three months that we've had our newest bird in the fleet, she's already been through two lenses due to cracking from fod!
But they're also faster to extend and retract, which is nice when performing an op check.

As far as the original question (WHY Boeing moved them), notice that when Boeing redesigned the wing for the 737NG, the flap canoes changed shape entirely.
There's not room left for a landing light, as the canoe went from wide and flat to narrow and tall.
That's my best observation, anyway.
 
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HAWK21M
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RE: 737 Landing Light Question(s)

Fri Feb 13, 2009 3:19 pm



Quoting AA737-823 (Reply 12):
I am on the 737 (though as a tech, not a cap'n), and I am not aware of ANY relationship between landing lights coming on and engines going off.

Exactly why,since I've not heard this in Mx too.

Quoting AA737-823 (Reply 12):
There's a linkage arm that connects the light assembly to a stationary portion of the wing, and as the canoe moves downward, the arm adjusts the angle of the lamp upward, resulting in a more-or-less zero net affect.

The Bellcrank operates the canoe fairing.The centralising of the lights are by two microswitches on either end of the retractable light assy that senses signal to the square threaded motor drive shaft to move the assy.

regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
AA737-823
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RE: 737 Landing Light Question(s)

Mon May 25, 2009 10:16 pm



Quoting HAWK21M (Reply 13):
The Bellcrank operates the canoe fairing.The centralising of the lights are by two microswitches on either end of the retractable light assy that senses signal to the square threaded motor drive shaft to move the assy.

We disagree.
There's a linkage arm that is connected directly to the lamp/motor housing unit. You can push and pull on the linkage, and it moves the lamp.
I replaced one just a few weeks ago.
 
josekmlb
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RE: 737 Landing Light Question(s)

Mon May 25, 2009 11:15 pm

I know that the MD-88 for DL is all the way out under the wing tip, But I remember when they came in and use to bust alot or break and have glass all over the ramp when they over heated. I have not seen that happen in along time now. Have they changed anything on that or is it because we only get one MD-88 now I dont see it as much anymore?
 
roseflyer
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RE: 737 Landing Light Question(s)

Tue May 26, 2009 4:02 am

So I have to ask, where do you guys think the lights should be? What design would be best for maintenance? Technically, both are not needed, so they could be replaced with a single light. Would that be beneficial?
If you have never designed an airplane part before, let the real designers do the work!
 
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HAWK21M
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RE: 737 Landing Light Question(s)

Tue May 26, 2009 7:49 am



Quoting AA737-823 (Reply 14):
You can push and pull on the linkage, and it moves the lamp.

I was referring to the focussing of the light to keep it in line with the longitudional axis irrespective of TE Flap position.

Quoting RoseFlyer (Reply 16):

So I have to ask, where do you guys think the lights should be? What design would be best for maintenance? Technically, both are not needed, so they could be replaced with a single light. Would that be beneficial?

Def Inboard at the Wing root LE,But the canoe light [classic]has a drag problem & the retractable light [NG] has FOD/water cracking issues.
regds
MEL.
I may not win often, but I damn well never lose!!! ;)

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