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Early 737s Vs NG - Are Any Parts Still The Same?  
User currently onlineViscount724 From Switzerland, joined Oct 2006, 24823 posts, RR: 22
Posted (6 years 4 months 4 days 1 hour ago) and read 3489 times:

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?

22 replies: All unread, jump to last
 
User currently offlineRoseFlyer From United States of America, joined Feb 2004, 9495 posts, RR: 52
Reply 1, posted (6 years 4 months 4 days 1 hour ago) and read 3488 times:

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!
User currently offlineTdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 2, posted (6 years 4 months 3 days 21 hours ago) and read 3439 times:



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.


User currently offlineHAWK21M From India, joined Jan 2001, 31667 posts, RR: 56
Reply 3, posted (6 years 4 months 3 days 18 hours ago) and read 3407 times:

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



Think of the brighter side!
User currently offlineStarlionblue From Greenland, joined Feb 2004, 16994 posts, RR: 67
Reply 4, posted (6 years 4 months 3 days 17 hours ago) and read 3405 times:



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."
User currently offlineRoseFlyer From United States of America, joined Feb 2004, 9495 posts, RR: 52
Reply 5, posted (6 years 4 months 3 days 11 hours ago) and read 3340 times:



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!
User currently offlineHAWK21M From India, joined Jan 2001, 31667 posts, RR: 56
Reply 6, posted (6 years 4 months 3 days 9 hours ago) and read 3310 times:



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



Think of the brighter side!
User currently offlineTristarSteve From Sweden, joined Nov 2005, 3977 posts, RR: 34
Reply 7, posted (6 years 4 months 3 days 8 hours ago) and read 3268 times:

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.


User currently offlineSoon7x7 From , joined Dec 1969, posts, RR:
Reply 8, posted (6 years 4 months 3 days 7 hours ago) and read 3260 times:

Basically, fuselage pressure vessel the same,... wings, tail feathers, fairings all redesigned. Overwing hatches open externally rather than internally.

User currently offlineRoseFlyer From United States of America, joined Feb 2004, 9495 posts, RR: 52
Reply 9, posted (6 years 4 months 3 days 6 hours ago) and read 3227 times:



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!
User currently offlineHAWK21M From India, joined Jan 2001, 31667 posts, RR: 56
Reply 10, posted (6 years 4 months 2 days 17 hours ago) and read 3120 times:



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



Think of the brighter side!
User currently offlineSXDFC From United States of America, joined Dec 2007, 2296 posts, RR: 19
Reply 11, posted (6 years 4 months 7 hours ago) and read 2970 times:

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.
User currently offlineHAWK21M From India, joined Jan 2001, 31667 posts, RR: 56
Reply 12, posted (6 years 3 months 4 weeks 1 day 16 hours ago) and read 2883 times:



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



Think of the brighter side!
User currently offlineVHHYI From Australia, joined Oct 2007, 97 posts, RR: 0
Reply 13, posted (6 years 3 months 4 weeks 1 day 3 hours ago) and read 2827 times:



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?



This Porsche is like an Airbus;an Engineering marvel, but without passion - Jeremy Clarkson
User currently onlineViscount724 From Switzerland, joined Oct 2006, 24823 posts, RR: 22
Reply 14, posted (6 years 3 months 4 weeks 1 day ago) and read 2799 times:



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.


User currently offlineAbqwildcat From United States of America, joined Jan 2008, 6 posts, RR: 0
Reply 15, posted (6 years 3 months 4 weeks 21 hours ago) and read 2772 times:



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.


User currently offlineTdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 16, posted (6 years 3 months 4 weeks 20 hours ago) and read 2764 times:



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.


User currently offlineHAWK21M From India, joined Jan 2001, 31667 posts, RR: 56
Reply 17, posted (6 years 3 months 3 weeks 6 days 16 hours ago) and read 2683 times:

http://en.wikipedia.org/wiki/Boeing_fuselage_Section_41
Good Info on Section 41.

regds
MEL



Think of the brighter side!
User currently onlineViscount724 From Switzerland, joined Oct 2006, 24823 posts, RR: 22
Reply 18, posted (6 years 3 months 3 weeks 5 days 23 hours ago) and read 2613 times:



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.


User currently offlineTdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 19, posted (6 years 3 months 3 weeks 5 days 22 hours ago) and read 2610 times:



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.



User currently offlinePhollingsworth From United Kingdom, joined Mar 2004, 825 posts, RR: 5
Reply 20, posted (6 years 3 months 3 weeks 5 days 13 hours ago) and read 2577 times:



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.


User currently offlineScooter01 From Norway, joined Nov 2006, 1199 posts, RR: 8
Reply 21, posted (6 years 3 months 3 weeks 5 days 13 hours ago) and read 2570 times:
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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



"We all have a girl and her name is nostalgia" - Hemingway
User currently offlineHAWK21M From India, joined Jan 2001, 31667 posts, RR: 56
Reply 22, posted (6 years 3 months 3 weeks 5 days 12 hours ago) and read 2562 times:



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

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



Think of the brighter side!
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