Viscount724
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Early 737s Vs NG - Are Any Parts Still The Same?

Tue Mar 25, 2008 12:22 am

To the untrained eye a 737-200 of 40 years ago looks much like the NG series being built today, although there have of course been many changes.

I'm just curious whether any parts of current 737NGs are identical to those used 40 years ago on the earliest 737s? A few that come to mind might be the radome, cockpit and/or cabin windows and passenger/galley service doors and overwing exits? Or have even those parts changed in at least some respect during that period?

What about the -300/400/500 series vs the NG? If a carrier operates both series (e.g. Southwest) are many parts interchangeable between the two models?
 
roseflyer
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RE: Early 737s Vs NG - Are Any Parts Still The Same?

Tue Mar 25, 2008 12:26 am

There are lots of parts that are the same. In fact many parts are even carryovers from the 727. There is no reason to redesign a part if you do not need to. Something designed 40 years ago might have been done on paper, but it doesn't mean that redesigning it will save weight or decrease cost. Without economic incentive, parts stay the same.
If you have never designed an airplane part before, let the real designers do the work!
 
tdscanuck
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RE: Early 737s Vs NG - Are Any Parts Still The Same?

Tue Mar 25, 2008 4:22 am



Quoting Viscount724 (Thread starter):
I'm just curious whether any parts of current 737NGs are identical to those used 40 years ago on the earliest 737s?

As RoseFlyer said, they certainly exist. Off the top of my head, I know there are some extrusions and some bulb seals for the 737NG that are still built to hand-done drawings from the 60's.

Quoting Viscount724 (Thread starter):
What about the -300/400/500 series vs the NG? If a carrier operates both series (e.g. Southwest) are many parts interchangeable between the two models?

Where possible, yes. Offhand, I know that the thrust reverser hydraulic control valve modules are exactly the same.

Tom.
 
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HAWK21M
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RE: Early 737s Vs NG - Are Any Parts Still The Same?

Tue Mar 25, 2008 7:59 am

Quite a lot of Similiarities more so from the -300/400/500 to the NGs rather than from the -100/200.
The sections 41,43,46,48 are more or less the same.doors are mostly same,the handle crank assy has varied.
Bulk cargo doors are similiar but the restraining mechanism has varied.
The Magnetic compass is similiar  Smile
A lot of components are similiar or a higher dash P/N too.

If something is working well,might as well stick to it.

regds
MEL
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Starlionblue
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RE: Early 737s Vs NG - Are Any Parts Still The Same?

Tue Mar 25, 2008 8:30 am



Quoting HAWK21M (Reply 3):
The Magnetic compass is similiar

Lol. Well I don't think the basic design of a magnetic compass has changed much in 100 years. Big grin
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
roseflyer
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RE: Early 737s Vs NG - Are Any Parts Still The Same?

Tue Mar 25, 2008 2:20 pm



Quoting Viscount724 (Thread starter):
A few that come to mind might be the radome, cockpit and/or cabin windows and passenger/galley service doors and overwing exits?

Much in the flight deck is the same. For example the steering system hasn't changed. In fact some part numbers are identical.

Not sure about cabin windows.

Doors are mostly the same.

Overwing exits have changed. They are no longer removable plug doors that are detached and laid on the seats or thrown out the window. Exit windows now rotate up which makes egress easier.
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: Early 737s Vs NG - Are Any Parts Still The Same?

Tue Mar 25, 2008 4:14 pm



Quoting RoseFlyer (Reply 5):
For example the steering system hasn't changed. In fact some part numbers are identical.

The Rudder steering disconnect mechanism uses a Transmitter & Reciever rather than the Piston position cartridge.

regds
MEL
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Tristarsteve
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RE: Early 737s Vs NG - Are Any Parts Still The Same?

Tue Mar 25, 2008 5:34 pm

well I have never worked on the NG, just B737-200/300/400/500.
But last week I ducked under a Malev B738 which was parked between my two nightstoppers, and stopped to look in the wheelwell. I was surprised to see the big mechanical spoiler mixer still there. This machine takes inputs from tyhe speedbrake handle by steel cables, and from the aileron servos by a rod(?) and mixes them with gears and outputs by steel cables to the spoiler actuators. I was amazed the Boeing had not replaced this with a computor. It looked identical to the one on the B737-200 which I used to have so much trouble rigging on D checks.
 
soon7x7
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RE: Early 737s Vs NG - Are Any Parts Still The Same?

Tue Mar 25, 2008 6:06 pm

Basically, fuselage pressure vessel the same,... wings, tail feathers, fairings all redesigned. Overwing hatches open externally rather than internally.
 
roseflyer
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RE: Early 737s Vs NG - Are Any Parts Still The Same?

Tue Mar 25, 2008 7:17 pm



Quoting TristarSteve (Reply 7):
I was surprised to see the big mechanical spoiler mixer still there. This machine takes inputs from tyhe speedbrake handle by steel cables, and from the aileron servos by a rod(?) and mixes them with gears and outputs by steel cables to the spoiler actuators. I was amazed the Boeing had not replaced this with a computor. It looked identical to the one on the B737-200 which I used to have so much trouble rigging on D checks

Many of the components in the wheel well have not changed. Hydraulic power and flight controls have not changed much. A lot of the parts like the one you are referring to have been changed slightly and are not the same part number, but overall the function is the same.

The 737NG is not fly by wire, so it does have all of those mechanical systems. Some were taken out when the NG was created, but there are many many steel cables running throughout the plane.

In the end, in order to change something on the 737 it has to cost less, save weight, decrease maintenance, decrease manufacturing time, reduce leaks/repairs or something along those lines. If it doesn't improve the airplane, it does not change.
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: Early 737s Vs NG - Are Any Parts Still The Same?

Wed Mar 26, 2008 8:09 am



Quoting TristarSteve (Reply 7):
It looked identical to the one on the B737-200 which I used to have so much trouble rigging on D checks.

That sure is one troublesome component tyo Rig.
I remember that Spoiler mixer very well  Smile
regds
MEL
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SXDFC
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RE: Early 737s Vs NG - Are Any Parts Still The Same?

Fri Mar 28, 2008 6:40 pm

As some might have seen in my other post about the 737 Cockpit window, its still the same from the 707 and 727days, I always wondered how they came up with the actual drawings for them, most cockpit windows are always a weird shape!
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: Early 737s Vs NG - Are Any Parts Still The Same?

Sat Mar 29, 2008 9:42 am



Quoting SXDFC (Reply 11):
As some might have seen in my other post about the 737 Cockpit window, its still the same from the 707 and 727days, I always wondered how they came up with the actual drawings for them, most cockpit windows are always a weird shape!

Section 41 was never varied for the B707/727/737.

regds
MEL
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VHHYI
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RE: Early 737s Vs NG - Are Any Parts Still The Same?

Sat Mar 29, 2008 10:19 pm



Quoting HAWK21M (Reply 12):
Section 41 was never varied for the B707/727/737.

Out of interest, could the 737 'eyebrow' window deletion be retrofited to the 70/727 as well?
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Viscount724
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RE: Early 737s Vs NG - Are Any Parts Still The Same?

Sun Mar 30, 2008 1:25 am



Quoting HAWK21M (Reply 12):
Section 41 was never varied for the B707/727/737.

How can that be true since the 707 fuselage is a foot deeper (top to bottom) than the 727/737? 707 fuselage height 14 ft. 2.5 in. (4.33m) and 727/737 13 ft 2 in. (4.01m). The doors and nose gear are also in different locations on the three types. If the 707's section 41 was used on the 727/737 the rear edge would not match up with the rest of the fuselage due to the different dimensions.
 
abqwildcat
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RE: Early 737s Vs NG - Are Any Parts Still The Same?

Sun Mar 30, 2008 4:25 am



Quoting Viscount724 (Reply 14):
If the 707's section 41 was used on the 727/737 the rear edge would not match up with the rest of the fuselage due to the different dimensions.

Indeed that's probably the case. I don't have a lot of familiarity with the 737, but the 41 section of the 767 and 777 are the same despite having quite different fuselage cross sections. The entire 41 section is not identical, but rather the first two-thirds or so. Aft of that, the section flares out to match the 777's large size or stays relatively small to match the smaller cross section of the 767. I suspect the 737/727/707 41 section matching works in a similar way.
 
tdscanuck
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RE: Early 737s Vs NG - Are Any Parts Still The Same?

Sun Mar 30, 2008 5:22 am



Quoting VHHYI (Reply 13):

Out of interest, could the 737 'eyebrow' window deletion be retrofited to the 70/727 as well?

Yes.

Quoting Viscount724 (Reply 14):
Quoting HAWK21M (Reply 12):
Section 41 was never varied for the B707/727/737.

How can that be true since the 707 fuselage is a foot deeper (top to bottom) than the 727/737? 707 fuselage height 14 ft. 2.5 in. (4.33m) and 727/737 13 ft 2 in. (4.01m). The doors and nose gear are also in different locations on the three types. If the 707's section 41 was used on the 727/737 the rear edge would not match up with the rest of the fuselage due to the different dimensions.

It depends on where you draw the line between Section 41 and Section 43. It's entirely possible that the 727/737 nose is the same profile as the 707 but ends earlier before it's flared out to the full 707 fuselage dimension.

Tom.
 
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HAWK21M
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RE: Early 737s Vs NG - Are Any Parts Still The Same?

Mon Mar 31, 2008 9:03 am

I may not win often, but I damn well never lose!!! ;)
 
Viscount724
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RE: Early 737s Vs NG - Are Any Parts Still The Same?

Tue Apr 01, 2008 2:54 am



Quoting HAWK21M (Reply 17):
http://en.wikipedia.org/wiki/Boeing_fuselage_Section_41
Good Info on Section 41.

Wikipedia is often not very accurate. But leaving that aside, if Section 41 extends to aft of the cockpit as the Wikipedia item says, I still can't see how it could be identical on the 707/720 and 727/737 or the area where it meets the rest of the fuselage would have an obvious "kink" due to the one foot difference in fuselage height between the 707 and 727/737. The 707 cockpit section also looks deeper (at least to my eyes) in photos when comparing it to the same area on the 727/737.
 
tdscanuck
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RE: Early 737s Vs NG - Are Any Parts Still The Same?

Tue Apr 01, 2008 3:07 am



Quoting Viscount724 (Reply 18):
Wikipedia is often not very accurate. But leaving that aside, if Section 41 extends to aft of the cockpit as the Wikipedia item says, I still can't see how it could be identical on the 707/720 and 727/737 or the area where it meets the rest of the fuselage would have an obvious "kink" due to the one foot difference in fuselage height between the 707 and 727/737.



Quoting Tdscanuck (Reply 16):
It depends on where you draw the line between Section 41 and Section 43. It's entirely possible that the 727/737 nose is the same profile as the 707 but ends earlier before it's flared out to the full 707 fuselage dimension.

 
phollingsworth
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RE: Early 737s Vs NG - Are Any Parts Still The Same?

Tue Apr 01, 2008 12:25 pm



Quoting Abqwildcat (Reply 15):
Indeed that's probably the case. I don't have a lot of familiarity with the 737, but the 41 section of the 767 and 777 are the same despite having quite different fuselage cross sections. The entire 41 section is not identical, but rather the first two-thirds or so. Aft of that, the section flares out to match the 777's large size or stays relatively small to match the smaller cross section of the 767. I suspect the 737/727/707 41 section matching works in a similar way.

While the upper lobe of the fuselage has the same mold lines for all of the Boeing narrowbodies, 707-757. The lower lobes are quite different. I believe the 727 actually has two different lower lobes, one forward of the wing and one aft. This also means that the 737 has a very similar, if not quite the same, upper section 41 as the 707. One other thing to note is that the actual structure of the fuselage panels has changed through the course of the different aircraft, from cold bonded to chem-milled on the B757, I don't know if this improvement was incorporated on the B737NG.
 
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Scooter01
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RE: Early 737s Vs NG - Are Any Parts Still The Same?

Tue Apr 01, 2008 12:33 pm



Quoting Viscount724 (Thread starter):
I'm just curious whether any parts of current 737NGs are identical to those used 40 years ago on the earliest 737s?

What about the nose-gear doors?  duck 

Scooter01
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HAWK21M
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RE: Early 737s Vs NG - Are Any Parts Still The Same?

Tue Apr 01, 2008 1:31 pm



Quoting Scooter01 (Reply 21):
What about the nose-gear doors

The Doors are the same But the Operating Pushrod is varied.
regds
MEL
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