Moderators: richierich, ua900, PanAm_DC10, hOMSaR

 
User avatar
rjsampson
Topic Author
Posts: 445
Joined: Sat Jul 31, 2010 12:00 am

737 Split Scimitars missing dorsal winglet

Sun Jul 15, 2018 11:23 pm

I live near the KSAN approach and it seems like nearly half the time, I’ll see 737 equipped with SS winglets missing the “dorsal” structure on one wing. Would this incur any fuel penalty? Anyone have insight on why this seems to be a very common occurance?
"..your eyes will be forever turned skyward, for there.." yeah we know the DaVinci quote. Unfortunately, we're grounded :(
 
B6JFKH81
Posts: 2152
Joined: Thu Mar 16, 2006 6:35 am

Re: 737 Split Scimitars missing dorsal winglet

Mon Jul 16, 2018 1:36 am

Considering the Split Scimitar retrofit assemblies are all based on the existing blended winglet, missing a “dorsal” fin of the winglet would cause the entire winglet assembly to be missing as the ventral fin is a part of the assembly from what I can see so you can’t have one missing without the other. Not too familiar with the 737 but just looking at pictures it seems it is an all-or-nothing wing tip assembly.
"If you do not learn from history, you are doomed to repeat it"
 
User avatar
rjsampson
Topic Author
Posts: 445
Joined: Sat Jul 31, 2010 12:00 am

Re: 737 Split Scimitars missing dorsal winglet

Mon Jul 16, 2018 2:08 am

Oops, I totally mixed up my terminology: it was the ventral fin... Thoughts?
"..your eyes will be forever turned skyward, for there.." yeah we know the DaVinci quote. Unfortunately, we're grounded :(
 
Raventech
Posts: 208
Joined: Thu Aug 30, 2012 10:25 pm

Re: 737 Split Scimitars missing dorsal winglet

Mon Jul 16, 2018 2:10 am

B6JFKH81 wrote:
Considering the Split Scimitar retrofit assemblies are all based on the existing blended winglet, missing a “dorsal” fin of the winglet would cause the entire winglet assembly to be missing as the ventral fin is a part of the assembly from what I can see so you can’t have one missing without the other. Not too familiar with the 737 but just looking at pictures it seems it is an all-or-nothing wing tip assembly.


I think your thinking that their made like MAX style winglets as one piece. The Split Scimitar winglets are normal Blended winglets with a new cap on top and anchor points added to the side to mount the lower section (and associated reinforcement).

Looking at these photos they are indeed a 2 piece assembly
https://www.google.com/search?q=split+s ... =943&dpr=1
 
B6JFKH81
Posts: 2152
Joined: Thu Mar 16, 2006 6:35 am

Re: 737 Split Scimitars missing dorsal winglet

Mon Jul 16, 2018 2:34 am

Raventech wrote:
B6JFKH81 wrote:
Considering the Split Scimitar retrofit assemblies are all based on the existing blended winglet, missing a “dorsal” fin of the winglet would cause the entire winglet assembly to be missing as the ventral fin is a part of the assembly from what I can see so you can’t have one missing without the other. Not too familiar with the 737 but just looking at pictures it seems it is an all-or-nothing wing tip assembly.


I think your thinking that their made like MAX style winglets as one piece. The Split Scimitar winglets are normal Blended winglets with a new cap on top and anchor points added to the side to mount the lower section (and associated reinforcement).

Looking at these photos they are indeed a 2 piece assembly
https://www.google.com/search?q=split+s ... =943&dpr=1


....and if you look at the pictures you reference, the dorsal fin is the primary structure and the ventral fin is attached to it. So, you can’t have a dorsal fin missing without the entire assembly missing.

As per the OP, he was discussing the ventral fin actually what was being asked about, and in that case I really don’t know what the MMEL or SDL calls out for on the 737. I was not talking about the MAX wingtip device as that seems to be a single part.
"If you do not learn from history, you are doomed to repeat it"
 
User avatar
DocLightning
Posts: 21804
Joined: Wed Nov 16, 2005 8:51 am

Re: 737 Split Scimitars missing dorsal winglet

Mon Jul 16, 2018 3:00 pm

The terminology used in the patents is "upward wing-like element" and "downward wing-like element." Which is wordy, I know.

Anyway, the upward WLE cannot be MELed because the nav lights are integrated into the structure. I believe the downward WLE can be MELed but flying with only one comes at a small penalty because in addition to the overall loss of lift, there will be an asymmetrical lift on the aircraft and the ailerons (and hence the rudder) will have to compensate.
-Doc Lightning-

"The sky calls to us. If we do not destroy ourselves, we will one day venture to the stars."
-Carl Sagan
 
User avatar
rjsampson
Topic Author
Posts: 445
Joined: Sat Jul 31, 2010 12:00 am

Re: 737 Split Scimitars missing dorsal winglet

Mon Jul 16, 2018 3:26 pm

"downward wing-like element."

Anyway, the upward WLE cannot be MELed because the nav lights are integrated into the structure. I believe the downward WLE can be MELed but flying with only one comes at a small penalty because in addition to the overall loss of lift, there will be an asymmetrical lift on the aircraft and the ailerons (and hence the rudder) will have to compensate.


Can anyone shine light on, or speculate, why this element is so commonly missing said element? From my eye, like 40% of the many so equippedAre they more prone to damage requiring maintenance more frequently than other parts? It would suggest poor engineering to me.
"..your eyes will be forever turned skyward, for there.." yeah we know the DaVinci quote. Unfortunately, we're grounded :(
 
flybaurlax
Posts: 616
Joined: Sun Oct 05, 2008 12:34 am

Re: 737 Split Scimitars missing dorsal winglet

Mon Jul 16, 2018 5:09 pm

You can CDL the ventral strake. If you remove one, you have to remove the other so you don't have asymmetry. There is no performance penalty at my airline due to the fact that we consider both SSW and Blended winglet the same.

The reason they are removed so frequently is due to the fact that they disappear at night when driving up behind them. You really can't see them, and if an operation doesn't have good ramp practices, trucks try to go under the wing and boom it's ripped off.
Boilerup! Go Purdue!
 
User avatar
DocLightning
Posts: 21804
Joined: Wed Nov 16, 2005 8:51 am

Re: 737 Split Scimitars missing dorsal winglet

Mon Jul 16, 2018 9:14 pm

rjsampson wrote:
"downward wing-like element."

Anyway, the upward WLE cannot be MELed because the nav lights are integrated into the structure. I believe the downward WLE can be MELed but flying with only one comes at a small penalty because in addition to the overall loss of lift, there will be an asymmetrical lift on the aircraft and the ailerons (and hence the rudder) will have to compensate.


Can anyone shine light on, or speculate, why this element is so commonly missing said element? From my eye, like 40% of the many so equippedAre they more prone to damage requiring maintenance more frequently than other parts? It would suggest poor engineering to me.


The fact that the downward WLE projects downward makes it an easy thing for ground vehicles to hit.
flybaurlax wrote:
You can CDL the ventral strake. If you remove one, you have to remove the other so you don't have asymmetry. There is no performance penalty at my airline due to the fact that we consider both SSW and Blended winglet the same.


In reality, there is a performance penalty of a couple of percent. Your company may choose to ignore it because it doesn't affect handling like the upward WLE does (it increases rotation rate and crews need to be prepared to avoid tail strikes) and it makes it simpler from an operational perspective. I swear I've seen some A/C flying with only one attached. Maybe I was imagining it?

It's puzzling to me that in such a procedure-conscious and safety-conscious industry that nobody has figured out how to keep people from driving into the downward WLE.
-Doc Lightning-

"The sky calls to us. If we do not destroy ourselves, we will one day venture to the stars."
-Carl Sagan
 
JAGflyer
Posts: 3571
Joined: Tue Aug 10, 2004 5:31 am

Re: 737 Split Scimitars missing dorsal winglet

Mon Jul 16, 2018 11:39 pm

flybaurlax wrote:
The reason they are removed so frequently is due to the fact that they disappear at night when driving up behind them. You really can't see them, and if an operation doesn't have good ramp practices, trucks try to go under the wing and boom it's ripped off.


That is why our airline's ground handling practice is to cone them (one at the tip of each wing, one in front of each engine, and one at the tail).
If you flew today, thank a Flight Dispatcher!
 
DL777200LR
Posts: 150
Joined: Fri Nov 20, 2015 12:15 am

Re: 737 Split Scimitars missing dorsal winglet

Mon Jul 16, 2018 11:55 pm

rjsampson wrote:
Oops, I totally mixed up my terminology: it was the ventral fin... Thoughts?



Im assuming you mean the lower, smaller (vertical fin) part of the scimitar. If that part of the winglet is damaged, it can be removed per the CDL, however the other winglet ( vertical fin) must also be removed. Exactly what happened today on a DL 739 today.
Nothing better than the sound of a 77W GE90-115B on engine start.
 
B6JFKH81
Posts: 2152
Joined: Thu Mar 16, 2006 6:35 am

Re: 737 Split Scimitars missing dorsal winglet

Tue Jul 17, 2018 1:30 am

DL777200LR wrote:
rjsampson wrote:
Oops, I totally mixed up my terminology: it was the ventral fin... Thoughts?



Im assuming you mean the lower, smaller (vertical fin) part of the scimitar. If that part of the winglet is damaged, it can be removed per the CDL, however the other winglet ( vertical fin) must also be removed. Exactly what happened today on a DL 739 today.


Out of curiosity, is the damage typically limited to the lower fin itself, or do inspections need to be performed at the connecting point of the fins, and the upper fin itself, for stress cracks and whatnot? How long does it take to remove the lower fins? What is used to cover that connection point while on CDL, speed tape?

Sorry so many questions, just not familiar with the SS wingtip devices at all!!
"If you do not learn from history, you are doomed to repeat it"
 
DL777200LR
Posts: 150
Joined: Fri Nov 20, 2015 12:15 am

Re: 737 Split Scimitars missing dorsal winglet

Tue Jul 17, 2018 3:05 am

B6JFKH81 wrote:
DL777200LR wrote:
rjsampson wrote:
Oops, I totally mixed up my terminology: it was the ventral fin... Thoughts?



Im assuming you mean the lower, smaller (vertical fin) part of the scimitar. If that part of the winglet is damaged, it can be removed per the CDL, however the other winglet ( vertical fin) must also be removed. Exactly what happened today on a DL 739 today.


Out of curiosity, is the damage typically limited to the lower fin itself, or do inspections need to be performed at the connecting point of the fins, and the upper fin itself, for stress cracks and whatnot? How long does it take to remove the lower fins? What is used to cover that connection point while on CDL, speed tape?

Sorry so many questions, just not familiar with the SS wingtip devices at all!!


No inspections required since it wasn’t a major damage just a dent from ground contact. I believe it’s held on by 8 bolts and I don’t believe there was a speed tape necessary.
Nothing better than the sound of a 77W GE90-115B on engine start.
 
User avatar
hOMSaR
Moderator
Posts: 2332
Joined: Tue Jan 19, 2010 4:47 am

Re: 737 Split Scimitars missing dorsal winglet

Tue Jul 17, 2018 2:56 pm

Where are you seeing these planes missing the lower part? If they're flying overhead and you're looking at them from below/at an angle, I'd almost guarantee that it's an optical illusion due to lighting. There's no way that 40% of split-scimitar 737s are missing a piece of the winglet.

I've seen plenty of split-scimitar 737s overhead where I swear they were missing the lower strake, but when I eventually got a good enough view at a different angle, I could then see them quite clearly.
I was raised by a cup of coffee.
 
User avatar
rjsampson
Topic Author
Posts: 445
Joined: Sat Jul 31, 2010 12:00 am

Re: 737 Split Scimitars missing dorsal winglet

Tue Jul 17, 2018 6:01 pm

hOMSaR wrote:
Where are you seeing these planes missing the lower part? If they're flying overhead and you're looking at them from below/at an angle, I'd almost guarantee that it's an optical illusion due to lighting. There's no way that 40% of split-scimitar 737s are missing a piece of the winglet.

I've seen plenty of split-scimitar 737s overhead where I swear they were missing the lower strake, but when I eventually got a good enough view at a different angle, I could then see them quite clearly.


On approach to 27 in San Diego. I too had thought that may be the case the first couple of times, after watching countless approaches, I am 100% certain I've seen several aircraft single ventral strake removed on many aircraft, on one wing only. I have a pretty good sample size, too. I take my dog to a park in Balboa Park, which has outstanding views of approaching aircraft. Not directly under the approach. And of course, being the AvGeek I am, I almost always at least glance at the approaching aircraft.

Additionally, I've seen the approach from many different locations and consistently observe the same thing. Now, 40% may be a subconscious exaggeration given that they really stick out, but it's not an inconsiderable number. Maybe one of the SW drivers here or MX would have insight?
"..your eyes will be forever turned skyward, for there.." yeah we know the DaVinci quote. Unfortunately, we're grounded :(
 
YYZatcboy
Posts: 1183
Joined: Fri Apr 22, 2005 2:15 am

Re: 737 Split Scimitars missing dorsal winglet

Wed Jul 18, 2018 8:21 am

It is not very common. Lots of people even sitting right next to the aircraft don't notice the Ventral Strake (what it's actually called) even when it is there. Most assuredly most of the missing ones you are "seeing" are tricks of the light and them blending in with the sky. They aren't very big and can blend in with surroundings.
DH1/3/4 MD11/88 L1011 A319/20/21/30/50/80 717 727 735/6/7/8/9 744 762/3 77E/W 788/789 E40/75/90 CRJ/700/705 CC150
J/S DH8D 736/7/8 763
 
fadecfault
Posts: 164
Joined: Mon Nov 05, 2007 8:44 pm

Re: 737 Split Scimitars missing dorsal winglet

Thu Jul 19, 2018 10:41 pm

rjsampson wrote:
hOMSaR wrote:
Where are you seeing these planes missing the lower part? If they're flying overhead and you're looking at them from below/at an angle, I'd almost guarantee that it's an optical illusion due to lighting. There's no way that 40% of split-scimitar 737s are missing a piece of the winglet.

I've seen plenty of split-scimitar 737s overhead where I swear they were missing the lower strake, but when I eventually got a good enough view at a different angle, I could then see them quite clearly.


On approach to 27 in San Diego. I too had thought that may be the case the first couple of times, after watching countless approaches, I am 100% certain I've seen several aircraft single ventral strake removed on many aircraft, on one wing only. I have a pretty good sample size, too. I take my dog to a park in Balboa Park, which has outstanding views of approaching aircraft. Not directly under the approach. And of course, being the AvGeek I am, I almost always at least glance at the approaching aircraft.

Additionally, I've seen the approach from many different locations and consistently observe the same thing. Now, 40% may be a subconscious exaggeration given that they really stick out, but it's not an inconsiderable number. Maybe one of the SW drivers here or MX would have insight?


If you are seeing many SWA aircraft with 1 missing ventral strake then you are seeing an optical illusion. SWA requires removal of both strakes for CDL if one is damaged. So right off the back you will not see an aircraft with one totally missing. Secondly I took a quick look in records at our -800 fleet and I only found one aircraft that had the strakes removed in the last six months.
The views and opinions written here are my own and do not reflect those of my employer.
 
strfyr51
Posts: 4855
Joined: Tue Apr 10, 2012 5:04 pm

Re: 737 Split Scimitars missing dorsal winglet

Thu Jul 19, 2018 10:55 pm

B6JFKH81 wrote:
Considering the Split Scimitar retrofit assemblies are all based on the existing blended winglet, missing a “dorsal” fin of the winglet would cause the entire winglet assembly to be missing as the ventral fin is a part of the assembly from what I can see so you can’t have one missing without the other. Not too familiar with the 737 but just looking at pictures it seems it is an all-or-nothing wing tip assembly.

Has anybody BOTHERED to look at the Configuration Deviation Log? It might surprise you..
 
B6JFKH81
Posts: 2152
Joined: Thu Mar 16, 2006 6:35 am

Re: 737 Split Scimitars missing dorsal winglet

Fri Jul 20, 2018 2:35 am

strfyr51 wrote:
B6JFKH81 wrote:
Considering the Split Scimitar retrofit assemblies are all based on the existing blended winglet, missing a “dorsal” fin of the winglet would cause the entire winglet assembly to be missing as the ventral fin is a part of the assembly from what I can see so you can’t have one missing without the other. Not too familiar with the 737 but just looking at pictures it seems it is an all-or-nothing wing tip assembly.

Has anybody BOTHERED to look at the Configuration Deviation Log? It might surprise you..


Considering I don't have access to that (if you couldn't tell by my screen name, my airline operates A320/321 and E190 so a 737 manual is not something in our library), it might surprise you that I couldn't look up that information...
"If you do not learn from history, you are doomed to repeat it"

Who is online

Users browsing this forum: No registered users and 10 guests

Popular Searches On Airliners.net

Top Photos of Last:   24 Hours  •  48 Hours  •  7 Days  •  30 Days  •  180 Days  •  365 Days  •  All Time

Military Aircraft Every type from fighters to helicopters from air forces around the globe

Classic Airliners Props and jets from the good old days

Flight Decks Views from inside the cockpit

Aircraft Cabins Passenger cabin shots showing seat arrangements as well as cargo aircraft interior

Cargo Aircraft Pictures of great freighter aircraft

Government Aircraft Aircraft flying government officials

Helicopters Our large helicopter section. Both military and civil versions

Blimps / Airships Everything from the Goodyear blimp to the Zeppelin

Night Photos Beautiful shots taken while the sun is below the horizon

Accidents Accident, incident and crash related photos

Air to Air Photos taken by airborne photographers of airborne aircraft

Special Paint Schemes Aircraft painted in beautiful and original liveries

Airport Overviews Airport overviews from the air or ground

Tails and Winglets Tail and Winglet closeups with beautiful airline logos