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ctrl_alt_del
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737-200 Engine Modifications

Mon Jun 25, 2007 11:45 pm

Early 737-200s had louver-type inlets on the nacelle to improve performance on takeoff and approach. On some of these aircraft the louvers were removed in favour of a solid nacelle. This would imply a reduction in performance. What further modifcations, if at all, were incoporated to account for the removal of the louvers, for example EI-ASB of Aerlingus


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the louvers are not closed in the newer photo but are missing. The same modifications can be observed on EI-ASA and EI-ASC. I also seem to remember that early 747-100 had these louvers also which were replaced by a solid nacelle. were they removed for maintainance reasons?
 
OPNLguy
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RE: 737-200 Engine Modifications

Tue Jun 26, 2007 12:30 am

They were also known as "sucker doors" and you might do a search using those terms since they've been discussed before, albeit long ago.

I can't address their use on the 747s, but on the 737s, they were standard equipment on the 737-200 "Basic" models, and were eliminated when Boeing started producing the 737-200 "Advanced" ("ADV") models (around 1972-1973) the latter model constituting the bulk of the -200 production.

The -200 ADV had other improvements like longer cowlings, and leading edge Krueger flaps that went closer towards the fuselage, as well as improved performance from more powerful JT8D variants like the -9, -15, and -17. (The -200 "Basic" had -7s installed). Max takeoff weights went up commensurate with whichever newer engine variant was installed, and max structural landing weights increased from the "Basic's" 98,000 lbs. to 103,000/105,000/107,000 lbs., respectively. Max takeoff weights went from the "Basic's" 109,000 lbs to 115,500/119,500/124,500 lbs., respectively. The fuel capacity of the ADVs was also higher.

I'm not personally aware of any retrofitting program that allowed "Basic" operators to install new ADV-type cowlings, but I guess it's possible, although it wouldn't have provided all the other performance improvements of the ADV versions.
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ctrl_alt_del
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RE: 737-200 Engine Modifications

Tue Jun 26, 2007 12:58 am


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Quote:
I'm not personally aware of any retrofitting program that allowed "Basic" operators to install new ADV-type cowlings, but I guess it's possible, although it wouldn't have provided all the other performance improvements of the ADV versions.



This is what I was getting at. If they simply put the ADV cowlings on the basic models they must have made other modifications to compensate....or maybe not.
 
OPNLguy
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RE: 737-200 Engine Modifications

Tue Jun 26, 2007 1:12 am

Quoting CTRL_ALT_DEL (Reply 2):
This is what I was getting at. If they simply put the ADV cowlings on the basic models they must have made other modifications to compensate....or maybe not.

The only reason I can even remotely think of for putting the newer ADV cowls on the older aircraft would have been for noise reduction, and as I mentioned before, it still would have been a "Basic" as far as performance went.

(The -200 Basic with -7 engines was a real dog that increasingly had trouble getting out of its own way once the temp went above 84F...)  Wink
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aeroweanie
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RE: 737-200 Engine Modifications

Tue Jun 26, 2007 1:53 am

The "sucker doors" are more properly called "blow-in doors". They would open when the engine required high massflows, such as during take-off. The trouble is that they produced inflow distortion at the fan face and a lot of noise. On 737-200 Advanceds, the inlet lip was redesigned, allowing for operations at higher massflows and the doors were eliminated. I believe these revised cowls have been retrofitted to all 737-200s.

I have stood 300' from a 737-200 with blow-in doors during a high power ground run and can testify that the noise is intense.
 
ctrl_alt_del
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RE: 737-200 Engine Modifications

Tue Jun 26, 2007 6:20 am

Interesting to hear that noise reduction was a factor. I thought that the "blow-in door" mechanism probably posed additional costs for overhaul. Were they servo activated or did they open automatically by the increased airflow itself once the airflow reached a threshold level?
As far as I can ascertain the modifications were made, at least to the Aer Lingus 737s, in the late 70s early 80s when noise was not really an issue. At that time they had they had BAC 1.11s without hushkits which used to make the 737s sound like a whisper-jet.

Anyway, many thanks.
 
N231YE
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RE: 737-200 Engine Modifications

Tue Jun 26, 2007 7:30 am

I know the model 737-200Adv's JT8D's are often said to be mounted in "quite" nacelles.

Quoting CTRL_ALT_DEL (Reply 5):
Were they servo activated or did they open automatically by the increased airflow itself once the airflow reached a threshold level?

These doors were spring-loaded, when the engine required more airflow than the intake could handle, the lower pressure essentially "sucked in [open]" the doors. When the intake met the requirements for the engine, the springs inside the nacelle kept the doors shut.

Quoting OPNLguy (Reply 1):
I'm not personally aware of any retrofitting program that allowed "Basic" operators to install new ADV-type cowlings, but I guess it's possible, although it wouldn't have provided all the other performance improvements of the ADV versions.

I wonder if there was a retrofit involved... I.E. the first 747-100s were fitted with blow in doors, but a modification (more of a hush-kit) eliminated these doors by use of an improved intake.
 
Viscount724
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RE: 737-200 Engine Modifications

Tue Jun 26, 2007 7:48 am

Quoting OPNLguy (Reply 1):
The -200 ADV had other improvements like longer cowlings, and leading edge Krueger flaps that went closer towards the fuselage, as well as improved performance from more powerful JT8D variants like the -9, -15, and -17. (The -200 "Basic" had -7s installed).

Many "basic" 737-200s also had the -9 engine.

I am almost certain that many early 737s with the blow-in doors later had the nacelles modified to remove them.
 
OPNLguy
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RE: 737-200 Engine Modifications

Tue Jun 26, 2007 8:38 am

Scroll down for differences between the -200 Basic and -200 ADV models...

http://www.b737.org.uk/history.htm#737-200
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HAWK21M
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RE: 737-200 Engine Modifications

Tue Jun 26, 2007 4:35 pm

Quoting AeroWeanie (Reply 4):
The "sucker doors" are more properly called "blow-in doors".

The Nose dome size varied depending if the Blow in doors were present on the Inlet cowl or Not.

Quoting Viscount724 (Reply 7):
I am almost certain that many early 737s with the blow-in doors later had the nacelles modified to remove them

Pls elaborate.

regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
Viscount724
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RE: 737-200 Engine Modifications

Wed Jun 27, 2007 5:57 am

Quoting HAWK21M (Reply 9):
Quoting Viscount724 (Reply 7):
I am almost certain that many early 737s with the blow-in doors later had the nacelles modified to remove them

Pls elaborate.

I meant that I'm sure I have seen photos of early 737s without the blow-in doors although they were built with them. Which makes me assume that the engine nacelles were modified to remove them at some point.
 
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LTU932
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RE: 737-200 Engine Modifications

Wed Jun 27, 2007 10:40 am

Quoting CTRL_ALT_DEL (Reply 2):

In the case of the 747-100, the engines with the blow-in doors were JT9D-3 if I'm not mistaken. Those were the original 747 engines. However, most if not all 747-100s have been re-engined with JT9D-7 engines, which produce more thrust and don't require the blow-in doors.
Sometimes the only thing more dangerous than a question is an answer. - Ferengi Rule of Acquisition 208
 
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HAWK21M
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RE: 737-200 Engine Modifications

Wed Jun 27, 2007 7:12 pm

Quoting Viscount724 (Reply 10):
Which makes me assume that the engine nacelles were modified to remove them at some point.

I don't think so.The Inlet cowls without the Blow in doors had a longer Nose dome assembly.
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
Viscount724
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RE: 737-200 Engine Modifications

Thu Jun 28, 2007 10:38 am

Quoting HAWK21M (Reply 12):
Quoting Viscount724 (Reply 10):
Which makes me assume that the engine nacelles were modified to remove them at some point.

I don't think so.The Inlet cowls without the Blow in doors had a longer Nose dome assembly.
regds
MEL

The following 3 photos of the same aircraft, originally delivered to CP Air in November 1968, then to PE and CO.. In the CP photo you can see the blow-in doors. In the 2 CO photos they are definitely not there when you enlarge the photos to the maximum. So I assume the forward part of the original nacelles must have been replaced at some point. When I said "modified" that's what I was referring to. The same change seems to appear on many other early 737s.


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HAWK21M
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RE: 737-200 Engine Modifications

Thu Jun 28, 2007 4:20 pm

As Explained.
The Blow in doors were installed on Nose Cowls which were using shorter Nose domes.When the Blow in doors were eliminated in future Nose Cowls the Nose dome used were longer ones.Remember the Nose dome houses the P2 sense probe for the EPR system hence Distance of Inlet to Pickup probe had to be maintained for accurate readings.

regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
747400sp
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RE: 737-200 Engine Modifications

Sun Oct 14, 2007 3:35 am

Did Canadian Airlines still have 737 200 with the blow-in-doors 1994 or 1995? I remeber a loud Canadian 737 200 landing at LAX at that time. Even in the 90s it was rare to hear a loud 737 during landing, so that is why that a/c stood out.
 
OPNLguy
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RE: 737-200 Engine Modifications

Sun Oct 14, 2007 4:12 am

Quoting 747400sp (Reply 15):
Did Canadian Airlines still have 737 200 with the blow-in-doors 1994 or 1995?

I seriously doubt it, but one never knows....
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HAWK21M
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RE: 737-200 Engine Modifications

Sun Oct 14, 2007 10:35 am

Quoting 747400sp (Reply 15):
Even in the 90s it was rare to hear a loud 737 during landing

Why was that.JT8Ds are always loud,including with noise supressor use.
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
UK_Dispatcher
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RE: 737-200 Engine Modifications

Sat Oct 27, 2007 10:54 am

Quoting OPNLguy (Reply 1):
The -200 ADV had other improvements like longer cowlings, and leading edge Krueger flaps that went closer towards the fuselage, as well as improved performance from more powerful JT8D variants like the -9, -15, and -17. (The -200 "Basic" had -7s installed).

Is there anything in this view of a rather dirty , worn wing which would confirm whether the aircraft was a -200 or -200Adv?

http://img.photobucket.com/albums/v316/flymajj/IMG_5931.jpg

The photo was taken in 1985 and was either a Britannia or Orion Airways example. Sadly I have no more info and would like to narrow it down a little more if possible. I know BY were still operating both variants at this time. Any info would be appreciated.
 
UK_Dispatcher
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RE: 737-200 Engine Modifications

Sat Oct 27, 2007 2:33 pm

Regarding my post above, I think it was actually a Britannia Airways flight rather than Orion. This is based on some very useful information I recieved a few months ago from Diesel1 regarding 80s charters out of NCL. Apparently in 1985 the only flights to AGP were operated by Britannia and Dan Air. It definately wasn't Dan Air as my first flight with them wasn't until 1988.

So, definately a chance it could have been a -200 or -200/Adv.

Any help appreciated.
 
OldAeroGuy
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RE: 737-200 Engine Modifications

Sat Oct 27, 2007 5:03 pm

Quoting UK_Dispatcher (Reply 18):
Is there anything in this view of a rather dirty , worn wing which would confirm whether the aircraft was a -200 or -200Adv?

The width of the nacelle strut faring says this is a -200Adv. The -200 had a rather narrow strut fairing. It was widened on the -200Adv to make a better seal with the inboard Kreuger and the outboard slat in the deployed position of these leading edge devices. The result was an improved CLmax.
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UK_Dispatcher
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RE: 737-200 Engine Modifications

Sat Oct 27, 2007 9:04 pm

Quoting OldAeroGuy (Reply 20):
The width of the nacelle strut faring says this is a -200Adv.

Thanks for the info - I suspected it was a -200/Adv from looking at a few photos a couple of hours ago. Pity I can't narrow it down any more than that though. I loved planes as a kid when this photo was taken but just wish now that I had collected the reg's of the aircraft I flew in at the time. Shame these aircraft did not carry the reg on the wing!
 
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HAWK21M
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RE: 737-200 Engine Modifications

Sun Oct 28, 2007 7:13 am

Quoting UK_Dispatcher (Reply 21):
Shame these aircraft did not carry the reg on the wing!

It would be on the top & bottom of alternative Wings.
regds
MEL
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UK_Dispatcher
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RE: 737-200 Engine Modifications

Mon Oct 29, 2007 7:14 pm

Quoting HAWK21M (Reply 22):
It would be on the top & bottom of alternative Wings.
regds
MEL

I should have sat on the other side then, hey?

If there were enough photos around of Britannia B737-200s in 1985 I might be able to identify it by the dirt and scratch patterns on the wing  Wink You never know!
 
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HAWK21M
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RE: 737-200 Engine Modifications

Wed Oct 31, 2007 9:23 am

Quoting UK_Dispatcher (Reply 23):
I should have sat on the other side then, hey

Thats an option  Smile
Out here Registration & Nationality marks have a specific size & location specified.
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
Clydenairways
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RE: 737-200 Engine Modifications

Mon Nov 05, 2007 4:11 pm

Not every Airline modified their Non Advanced 737's with new inlet cowl's like Aer Lingus did. French Charter Airline Euralair was a regular into Dublin and kept the original cowl type right up until the aircraft went out of service in the late 90's.
There was a distinct enough difference in sound to be able to tell a Euralair 737 on approach from inside the house before looking out the window.

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747fan
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RE: 737-200 Engine Modifications

Mon Nov 05, 2007 7:52 pm

Quoting OPNLguy (Reply 3):
(The -200 Basic with -7 engines was a real dog that increasingly had trouble getting out of its own way once the temp went above 84F...)

It would be safer to say that the takeoff performance of any JT8D, rather its a -7, -9A, or -219, suffers when the temp. is at least in the 84-90F range. This is especially true with a 727-200, just ask anybody who regularly spotted in Atlanta during the summer about 10+ years ago. I can testify to being on a 727 that had about a 45 second takeoff run on a 90F day in ATL back in the mid '90's.

Quoting LTU932 (Reply 11):
In the case of the 747-100, the engines with the blow-in doors were JT9D-3 if I'm not mistaken. Those were the original 747 engines. However, most if not all 747-100s have been re-engined with JT9D-7 engines, which produce more thrust and don't require the blow-in doors.

 checkmark  I'm 99% positive that all 747-100's now have the JT9D-7, which is basically just an improved, more powerful version of the JT9D-3. Those original 43K lb. thrust JT9D-3's on the 741 were notoriously underpowered and were well-known for having reliability issues, such as compressor stalls, overheating/flameouts, and "ovalisation" (I won't go into that). In fact, the inaugural PanAm 747-100 revenue flight from JFK-LHR was delayed about 3 hours due to engine problems. Even 741's w/ the 47K lb. thrust JT9D-7A engines are underpowered, just watch a Kalitta or UPS 741 takeoff from EWR or SDF on a hot summer day. On a side note, I have heard on this forum that planes w/ blow-in door-equipped engines were noticeably noisier.
I'm surprised nobody has mentioned the P&W JT3D blow-in doors on the 707:

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And you can't forget the GE TF39 on the C-5 Galaxy:

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HAWK21M
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RE: 737-200 Engine Modifications

Sat Nov 10, 2007 7:45 am

Quoting Clydenairways (Reply 25):
French Charter Airline Euralair was a regular into Dublin and kept the original cowl type right up until the aircraft went out of service in the late 90's.

The New Nose cowl also warrants a new Nose dome assy.
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
johnclipper
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RE: 737-200 Engine Modifications

Tue Dec 04, 2007 4:34 am

And don't forget that the early 737-100s and -200s had the shorter JT8D tailpipe. The engine was more stubby than the subsequent models.
"Flown every aircraft since the Wright Flyer" (guys, if you take this literally, then you need to get a life...)
 
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HAWK21M
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RE: 737-200 Engine Modifications

Tue Dec 04, 2007 10:18 am



Quoting JohnClipper (Reply 28):
And don't forget that the early 737-100s and -200s had the shorter JT8D tailpipe. The engine was more stubby than the subsequent models

Are you talking of the B732 basic.
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
Viscount724
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RE: 737-200 Engine Modifications

Wed Dec 05, 2007 4:18 am



Quoting HAWK21M (Reply 29):
Quoting JohnClipper (Reply 28):
And don't forget that the early 737-100s and -200s had the shorter JT8D tailpipe. The engine was more stubby than the subsequent models

Are you talking of the B732 basic.

I think he's talking about the original 737-100/200 thrust reverser design which turned out to be less effective than intended and was completely redesigned and retrofitted on the 737s that had already been delivered with the original design. The new design resulted in a much longer nacelle with the reversers extending several feet behind the wing. The original design ended roughly even with the trailing edge of the wing.

Original reversers:


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Modified reversers:


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HAWK21M
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RE: 737-200 Engine Modifications

Wed Dec 05, 2007 9:33 am



Quoting Viscount724 (Reply 30):
original 737-100/200 thrust reverser design

Any close up on that type of TR.
regds
MEL
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Buzz
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RE: 737-200 Engine Modifications

Wed Dec 05, 2007 10:31 am

Hi MEL, Buzz here. With the original "shorty" thrust reverser, I'll have to tell a story that the old-timers of 20 years ago told me. Of course in an airplane you want the parts to be small and lightweight. So the original idea was to use the 727 pneumatic driven T-R's.
But when the reversers were deployed and lots of reverse thrust was applied there was so much extra air being dumped under the flaps.... causing lift... that the braking was reduced.
And the 727 pneumatic reversers were tempermental... too much lube, too little lube, not enough bleed air to cycle the reverser. So along with a 4 foot tailpipe extension (which put the reverser aft of the flaps), Boeing put a hydraulic operated reverser on the rest of the Guppy (737) fleet.

I have some drawings from a 1967 Boeing sales booklet of the 737, but I don't know who might have pictures.

g'day
 
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HAWK21M
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RE: 737-200 Engine Modifications

Wed Dec 05, 2007 8:54 pm



Quoting Buzz (Reply 32):
So the original idea was to use the 727 pneumatic driven T-R's.
But when the reversers were deployed and lots of reverse thrust was applied there was so much extra air being dumped under the flaps.... causing lift... that the braking was reduced.

Wasn't that the reason for the Tilt to the T/Rs

Quoting Buzz (Reply 32):
And the 727 pneumatic reversers were tempermental

Pneumatic leaks can be tough to detect too.

regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
Buzz
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RE: 737-200 Engine Modifications

Thu Dec 06, 2007 12:18 pm

Hi MEL, Buzz here.
"Was that the reason to tilt the reversers?" Well, I was only a kid when they were designing it (grin). But consider where the exhaust will blow: If the reverser were oriented horizontally, #2 engine might kick up FOD into #1 engine and vice-versa. And you'd be adding more air under the flaps... causing a problem if you're trying to get the weight from the wings onto the tires for better braking. If the reversers were oriented vertically, they are likely to drag into the pavement when you deploy them - although ours were wired with a NLG squat switch so they wouldn't deploy unless there was weight on the NLG.
I guess having the reversers angled was the best compromise: you're sending one stream of air toward the top of the fuselage (ours used to get sooty up there) and one stream of air down and toward the wingtip.

And I agree, leaks in the pneumatics can be hard to find on a dirty / oily pylon at 4 in the morning. I don't miss that part of working on the Tri-Jet.

g'day
 
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longhauler
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RE: 737-200 Engine Modifications

Mon Dec 10, 2007 1:34 am



Quoting Viscount724 (Reply 10):
I meant that I'm sure I have seen photos of early 737s without the blow-in doors although they were built with them. Which makes me assume that the engine nacelles were modified to remove them at some point.

You are absolutely right. When the B737 BSCs were delivered to CP they had blow in doors, as were the B737 BSCs delivered to PV (Eastern Provincial which merged into CP in the early 1980s.) By the time I flew them, 1990, they were modified to a similar, but NOT the same as the B737 ADV. The biggest external difference was the elimination of the blow-in doors. My manual stated this was for noise reduction.

Quoting HAWK21M (Reply 33):
Wasn't that the reason for the Tilt to the T/Rs

This was to reduce the possibility of FOD as the lower bucket would now blow outboard of the intake instead of directly under it.
Just because I stopped arguing, doesn't mean I think you are right. It just means I gave up!
 
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HAWK21M
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RE: 737-200 Engine Modifications

Mon Dec 10, 2007 8:52 am



Quoting Buzz (Reply 34):
"Was that the reason to tilt the reversers



Quoting LongHauler (Reply 35):
This was to reduce the possibility of FOD as the lower bucket would now blow outboard of the intake instead of directly under it

I remember reading someplace in a book on Boeing 737 about this tilt being added to improve the Braking effeciemcy as the Impact when T/Rs were Vertically mounted caused the Wheels to lift weight off the surface.

regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
Viscount724
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RE: 737-200 Engine Modifications

Tue Dec 11, 2007 1:04 am



Quoting HAWK21M (Reply 36):
Quoting Buzz (Reply 34):
"Was that the reason to tilt the reversers


Quoting LongHauler (Reply 35):
This was to reduce the possibility of FOD as the lower bucket would now blow outboard of the intake instead of directly under it

I remember reading someplace in a book on Boeing 737 about this tilt being added to improve the Braking effeciemcy as the Impact when T/Rs were Vertically mounted caused the Wheels to lift weight off the surface.

Some DC-9s also have their reversers tilted slightly. For example, AC DC-9s had the tilted reversers while NW's are horizontal (although with NW DC-9s originating from so many sources they may have a mix of both types). I vaguely recall reading many years ago that AC was involved in this modification as they didn't consider the original horizontal DC-9 reverser design to be as effective as they should be. The tilted modification was then developed and I know all AC DC-9-30s had the tilted reversers, but I have seen many other DC-9s with the original horizontal design. You can see the difference when you enlarge the following photos.

Tilted:


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Horizontal:


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HAWK21M
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RE: 737-200 Engine Modifications

Tue Dec 11, 2007 2:50 pm



Quoting Viscount724 (Reply 37):
I vaguely recall reading many years ago that AC was involved in this modification as they didn't consider the original horizontal DC-9 reverser design to be as effective as they should be.

Any SB No.
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
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longhauler
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RE: 737-200 Engine Modifications

Tue Dec 11, 2007 5:03 pm

I remember as a kid many (many!) years ago, reading in Air Canada's in house employee magazine, "Horizons", talking about tilting the Thrust Reverse on the DC-9s with the intent of eliminating FOD. There were many before and after pictures and diagrams showing how FOD would be reduced. The area where the lower bucket's thrust hitting the ground was moved from in front of the engine to the side of the engine.

I recall that the talk was they invented the concept and were doing mods at the Dorval Maintenance base. I am not certain AC actually invented the concept, it was simply what they alluded!  Smile
Just because I stopped arguing, doesn't mean I think you are right. It just means I gave up!
 
AirframeAS
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RE: 737-200 Engine Modifications

Fri Dec 14, 2007 12:49 pm

I was told that the reason for the (IE: AS 732QC) tilt on the TR was to prevent the aircraft from having the tail 'jumping up', so Boeing had the bottom clamshell away from the fuselage and the top clamshell towards the top of the fuselage. Imagine if you put the bottom clamshell towards the bottom of the fuselage, the tail will jump with all that air coming out of the engine, underneith the plane.

Getting all the soot off of the aft of the 732QC was a royal pain in the butt during heavy checks!
A Safe Flight Begins With Quality Maintenance On The Ground.
 
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HAWK21M
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RE: 737-200 Engine Modifications

Sat Dec 15, 2007 6:41 am



Quoting AirframeAS (Reply 40):
Getting all the soot off of the aft of the 732QC was a royal pain in the butt during heavy checks!

Not if its done reguraily on the Line  Smile
regds
MEL
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AirframeAS
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RE: 737-200 Engine Modifications

Sat Dec 15, 2007 3:28 pm



Quoting HAWK21M (Reply 41):
Not if its done reguraily on the Line  Smile

Not while its intra-Alaska....thats a total different story!
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HAWK21M
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RE: 737-200 Engine Modifications

Sun Dec 16, 2007 9:02 am



Quoting AirframeAS (Reply 42):
Not while its intra-Alaska....thats a total different story!

Shouldn't the Snow provide the Shield  Smile
regds
MEL
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UK_Dispatcher
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RE: 737-200 Engine Modifications

Mon Dec 23, 2013 5:47 pm

Whilst resurrecting a 6.5 year old thread may not be the done thing, this was a fascinating discussion and I have a further question. Whilst wandering around the graveyard at THR in 2010, I stumbled upon one of three B737-286/Adv with the blow-in doors. I was surprised by this combination and did not think it existed. Any idea how common this was on the Advanced model and whether there were any other such examples?

These are the three early -200/Advanced aircraft that Iran Air recieved, all of which appear to have had the blow-in doors:

EP-IRF, B737-286/Adv, 20498/283, mfd 06/71
EP-IRH, B737-286C/Adv, 20500/286, mfd 08/71
EP-IRI, B737-286C/Adv, 20740/321, mfd 04/73

I believe this photo that I took was of EP-IRI:


Picture 068 by G-ARPO, on Flickr


Ian
 
LH707330
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RE: 737-200 Engine Modifications

Tue Dec 24, 2013 1:44 am

Quoting UK_Dispatcher (Reply 44):
Whilst resurrecting a 6.5 year old thread may not be the done thing

It's better than getting yelled at for repeating something that comes up every two weeks (e.g. 757NG )

Quoting UK_Dispatcher (Reply 44):
Any idea how common this was on the Advanced model and whether there were any other such examples?

Probably not very common. At this point, there was a pretty rapid advancement in technology, with the 737 and 747 both losing the blow-in doors around the same time due to noise reasons. Many frames from this era had a mix of older/newer parts, so I imagine they had a batch of the older inlets that needed a home and they ended up on these planes, possibly with a customer discount.

To the upthread discussion about the DC-9 buckets, AC did indeed invent these, and they later became production standard. Here's a article on the topic.
 
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HAWK21M
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RE: 737-200 Engine Modifications

Fri Dec 27, 2013 9:38 am

Quoting UK_Dispatcher (Reply 18):
Is there anything in this view of a rather dirty , worn wing which would confirm whether the aircraft was a -200 or -200Adv?

The VS Logo light on the wingtip.......
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musang
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RE: 737-200 Engine Modifications

Sun Dec 29, 2013 12:19 pm

Quoting Buzz (Reply 34):
I guess having the reversers angled was the best compromise: you're sending one stream of air toward the top of the fuselage (ours used to get sooty up there) and one stream of air down and toward the wingtip.

Another bonus - less ground debris blown at the landing gear and into the gear bay.

Regards - musang

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